Personality Pathways to Substance Abuse: Understanding Traits, Risks, and Treatment

This text-based course is an edited transcript of a live webinar, presented by Benjamin Ampel, MA, PhD candidate.

Introduction

The landscape of substance use disorders is complex, marked by a myriad of contributing factors that range from genetic predispositions to environmental influences. Among these, individual personality traits emerge as a critical dimension, offering profound insights into why certain individuals may be more susceptible to substance abuse, how their patterns of use might differ, and what therapeutic approaches could prove most effective. This article delves into the fascinating intersection of personality and substance use, providing a comprehensive overview of the theoretical frameworks and empirical evidence that illuminate these pathways. The primary focus will be on understanding how personality forms and influences behavior, identifying key personality traits linked to substance abuse, and predicting treatment outcomes of substance abuse based on personality.

The journey into understanding personality begins with a fundamental distinction between temperament and personality. Temperament, often considered the biological foundation, refers to the innate, genetically influenced behavioral and emotional patterns observable from early infancy. It is the raw material, the predispositions with which an individual is born. Personality, on the other hand, is the intricate tapestry woven when this biological temperament interacts with the environment—both the physical surroundings and the social milieu. It represents the consistent patterns of behavior that manifest across various situations and over time, shaping an individual's unique way of perceiving, thinking, and acting.

While the realm of personality is vast and multifaceted, this exploration will primarily center on the Big Five personality traits, a widely accepted and empirically supported model for describing human personality. Within this framework, particular emphasis will be placed on the dimensions of extraversion and introversion, given their significant and often counterintuitive implications for substance use. Furthermore, the discussion will extend to the Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS), two neurobiological systems that offer a deeper understanding of approach and avoidance motivations, which are profoundly relevant to addictive behaviors. By integrating insights from these models, this article aims to provide a nuanced perspective on how personality shapes the trajectory of substance use disorders and how this understanding can inform more targeted and effective clinical interventions.

Disclosures

Presenter Disclosure: Financial disclosures: Benjamin Ampel received an honorarium for presenting this course. Benjamin Ampel has published peer-reviewed articles on emotional regulation and personality, along with understanding the relationship between goal pursuit, self-regulation, and emotional regulation. Non-financial disclosures: Benjamin Ampel has no relevant non-financial relationships to disclose. Content Disclosure: This learning event does not focus exclusively on any specific product or service. Sponsor Disclosure: There is no external sponsor for this course.

Limitations and Risks

Personality is complex and multifaceted this webinar is not inclusive of all personality traits and factors that impact substance use. Practitioners should actively engage in supervision and self-reflection in an effort to reduce biased clinical judgments or reduced empathy for clients due to linking certain personality traits to substance abuse. Practitioners should practice culturally humility and utilize, and/or incorporate culturally responsive frameworks into practice.

Substance Use Disorders and Personality Overview

To begin, it is essential to establish a clear understanding of what constitutes a substance use disorder (SUD). According to the DSM-5 criteria, a diagnosis of SUD is based on a maladaptive pattern of substance use leading to significant impairment or distress. This pattern is manifested by at least two of the following criteria occurring within a 12-month period. The severity of the disorder is determined by the number of criteria met.

The DSM-5 outlines four main domains of criteria for SUD:

1. Impaired Control: This domain encompasses behaviors that indicate a loss of control over substance use. Examples include taking the substance in larger amounts or over longer periods than originally intended, a persistent desire or unsuccessful efforts to cut down or control substance use, spending a great deal of time obtaining, using, or recovering from the substance's effects, and experiencing a strong craving or desire to use the substance. These indicators reflect a diminished capacity to regulate one's own consumption, even in the face of intentions to reduce or cease use.
2. Social Impairment: This domain highlights the negative impact of substance use on an individual's social and occupational functioning. Criteria include a recurrent failure to fulfill major role obligations at work, school, or home due to substance use. It also involves continued substance use despite persistent social or interpersonal problems that are caused or worsened by the effects of the substance. Furthermore, giving up or reducing important social, occupational, or recreational activities because of substance use falls under this category, indicating a narrowing of interests and a prioritization of substance use over other life domains.
3. Risky Use: This domain pertains to the use of substances in situations that pose physical hazards or despite awareness of negative consequences. It includes recurrent substance use in physically hazardous situations, such as driving under the influence or operating machinery while intoxicated. It also involves continued substance use despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or worsened by the substance. This criterion underscores a disregard for one's own well-being in favor of continued substance use.
4. Pharmacological Criteria: These criteria relate to the physiological adaptations that occur with repeated substance use. Tolerance is a key indicator, characterized by a need for markedly increased amounts of the substance to achieve intoxication or the desired effect, or a markedly diminished effect with continued use of the same amount of the substance. Withdrawal is the other criterion, involving the development of a substance-specific syndrome due to the cessation of or reduction in substance use, or taking the substance (or a closely related substance) to relieve or avoid withdrawal symptoms. These physiological markers often signify a more entrenched pattern of dependence.

Understanding these diagnostic criteria provides a foundational context for exploring how personality intersects with substance use. As previously mentioned, personality is not merely an inherent trait but a dynamic construct shaped by the interplay of an individual's biological temperament and their environmental experiences. Temperament, the bedrock of personality, refers to the constitutionally based individual differences in emotional, motor, and attentional reactivity and self-regulation. These innate predispositions, evident even in infancy, influence how an individual interacts with and responds to their environment. For instance, some infants may exhibit high reactivity to novel stimuli, while others may be more subdued. These early differences can lay the groundwork for later personality traits, such as introversion or extraversion.

When this biological temperament consistently interacts with the physical and social environments over time, it solidifies into what we recognize as personality. This means that while an individual may be born with a certain predisposition, their experiences—their upbringing, social interactions, cultural context, and significant life events—all contribute to the refinement and expression of their personality traits. For example, a child with a naturally reactive temperament might, in a supportive and nurturing environment, develop coping mechanisms that lead to a resilient personality. Conversely, in a chaotic or unsupportive environment, the same temperament might manifest as heightened anxiety or withdrawal. Therefore, when examining the "personality pathways to substance abuse," it is crucial to consider this interplay, recognizing that both innate predispositions and learned behaviors contribute to an individual's vulnerability and their journey with substance use.

The Essential Trait Approach: The Big 5

To comprehend the profound influence of personality on substance use, it is imperative to first understand the prevailing framework for conceptualizing personality: the essential trait approach, which led to the development of the Big Five personality traits. The essential trait approach represents a scientific quest for a concise yet comprehensively predictive list of traits that can account for the broadest range of human behaviors. The core requirements for such a list are succinctness and non-redundancy, meaning each trait must be independent and contribute unique predictive power without overlapping significantly with others. The goal is to identify a parsimonious set of fundamental dimensions that can describe the vast complexity of human individual differences.

Given the immense vocabulary humans possess to describe personality across virtually every language and culture, a natural starting point for this quest was language itself. This led to the "lexical approach" to essential traits. The lexical hypothesis posits that the most important individual differences in human transactions will eventually become encoded in the natural language. In other words, if a personality trait is truly significant, people will have developed words to describe it. Researchers employing this approach began by sifting through dictionaries and asking individuals to describe people they knew well, identifying adjectives commonly used to characterize personality.

A seminal study illustrating this approach involved 1,300 raters who were given a list of 60 commonly used adjectives for describing people. Each rater was asked to think of a person they knew well and underline the adjectives they might use in a conversational description of that person. By analyzing which words were frequently used and which clustered together, researchers observed recurring patterns. For instance, while "bashful" and "bold" are antonyms, they both clearly describe aspects of the same underlying personality dimension. This systematic analysis of everyday language revealed that despite the seemingly endless array of descriptive terms, a finite set of core dimensions consistently emerged. This empirical process ultimately led to the identification of the Big Five personality traits, often remembered by the acronym OCEAN: Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism.

Let us briefly delineate each of these Big Five traits and their general implications, before delving into their specific connections to substance use:

1. Openness to Experience: This trait, sometimes referred to as intellect or culture, describes an individual's receptiveness to new ideas, experiences, and unconventional thinking. People high in openness are often characterized as original, daring, independent, and artistic. They possess a broad range of interests, are imaginative, and enjoy intellectual pursuits. Conversely, individuals low in openness tend to be more conventional, practical, and prefer routine. Interestingly, openness to experience has been linked to substance use, particularly with hallucinogenic substances. Research has even suggested that the consumption of certain psychedelics, such as psilocybin, can temporarily or even enduringly increase an individual's score on openness to experience. One study, for example, found that participants who took psilocybin mushrooms scored higher in openness to experience six months later compared to a control group.
2. Conscientiousness: This trait encompasses an individual's motivation to achieve goals and their discipline in pursuing them. It reflects a tendency to be organized, persistent, and planful. Individuals high in conscientiousness are typically careful, self-reliant, scrupulous, and goal-directed. They are often seen as responsible and hardworking. While conscientiousness might intuitively appear to be a protective factor against substance use due to its association with self-control and adherence to norms, its relationship is more nuanced. Paradoxically, highly conscientious individuals, when faced with significant professional setbacks, such as job loss, tend to experience more profound negative emotional responses, including increased depression, anxiety, and reduced life satisfaction. This heightened vulnerability to stress can, in some cases, lead to the development of maladaptive coping mechanisms, including substance use, as a means to manage intense emotional distress.
3. Extraversion/Introversion: This dimension describes the degree to which an individual is outgoing and derives energy from social interaction. Extraverts are typically talkative, friendly, spontaneous, and bold, seeking frequent interactions with others and often desiring dominance or leadership roles in groups. Introverts, conversely, are described as quiet, aloof, inhibited, or timid, preferring solitude and finding social interaction energetically draining. This trait is particularly central to the discussion of substance abuse, as it profoundly influences drug preferences and responsiveness to various therapeutic modalities. The intricate biological underpinnings of this dimension, particularly in relation to cortical arousal, will be explored in greater detail.
4. Agreeableness: This trait reflects an individual's tendency towards nurturance, emotional supportiveness, and a desire to maintain harmonious relationships. Agreeable individuals are often described as good-natured, helpful, trusting, and lenient. They tend to inhibit negative emotions for the sake of others and prioritize interpersonal harmony. Conversely, individuals low in agreeableness may be more competitive, skeptical, and less concerned with others' feelings. While not as directly linked to specific drug preferences as extraversion or neuroticism, agreeableness can influence an individual's social environment and their susceptibility to peer influence, which are significant factors in substance use initiation and maintenance.
5. Neuroticism/Emotional Stability: This trait represents an individual's tendency to experience negative emotions. Individuals high in neuroticism are often described as worrying, emotional, insecure, and jealous. They are prone to experiencing anxiety, depression, anger, and other distressing emotions. Conversely, individuals low in neuroticism, or high in emotional stability, are characterized as calm, unemotional, secure, and not easily perturbed. Neuroticism is a well-established risk factor for various mental health conditions, including substance use disorders, as individuals may turn to substances as a means of self-medication to alleviate intense emotional distress. The strong link between negative affect and substance use makes neuroticism a critical personality pathway to explore.

Each of these Big Five traits, in its own intricate way, contributes to an individual's unique vulnerability and trajectory concerning substance use disorders. While some traits may appear to be protective, their interaction with life events and other personality dimensions can create complex risk profiles. This foundational understanding of the Big Five sets the stage for a more focused examination of extraversion and introversion, and the underlying biological mechanisms that drive their distinct relationships with substance use.

Extraversion and Introversion: The Big Five

Extraversion and introversion constitute a fundamental dimension within the Big Five personality framework, yet their complexities often extend beyond common understanding. This trait is not merely about being outgoing or reserved; it delves into the very source of an individual's energy and their optimal level of environmental stimulation. When discussing extraversion and introversion, it is crucial to recognize that these are relative terms, describing an individual's position on a continuum compared to others. The majority of people, approximately 66%, fall within one standard deviation of the mean, exhibiting a blend of both introverted and extraverted tendencies. This middle ground is often referred to as "ambiversion." Ambiverts are not simply neutral; they possess the capacity to draw energy from both social interaction and solitude, adapting their behavior based on the situation. They might enjoy a lively party but also value quiet time for reflection, demonstrating a flexible mix of tendencies. However, for the purpose of understanding the more pronounced effects on substance use, focusing on the extreme ends of this spectrum—the highly introverted and highly extraverted individuals—provides clearer insights.

The concepts of introversion and extraversion were originally coined by Carl Jung and later popularized by Hans Eysenck, who proposed a strong biological basis for these differences. Eysenck's theory posited that introverts and extraverts differ in their baseline levels of cortical arousal, which influences how they restore energy. Introverts, as the prefix "intro" suggests, seek to restore their energy by pulling inward, into themselves. Social interactions, especially prolonged or intense ones, are energetically draining for them, leading to fatigue. They recharge in solitude, in environments with lower external stimulation. Conversely, extraverts, deriving their name from the prefix "extra," restore their energy by reaching outside of themselves, through social interaction and engagement with the external world. They find solitude and a lack of external stimulus to be draining and even boring, which depletes their energy. This fundamental difference in energy restoration is a cornerstone for understanding their distinct behavioral patterns.

As a direct consequence of these differing energy restoration mechanisms, introverts and extraverts exhibit notable differences in sociality, as articulated by Carver and Scheier (2016). Extraverts are inherently more likely to seek out social interactions. They are often drawn to group settings and tend to seek dominance within these groups, frequently assuming leadership roles. Furthermore, and for reasons that are biologically complex, extraverts tend to experience positive emotions more frequently in general. This propensity for positive affect can further reinforce their pursuit of stimulating social environments. For an individual to gauge their own position on this spectrum, a simple self-reflection can be illustrative: consider how you feel after leaving a large social gathering. An extravert might feel energized and even seek further social engagement, while an introvert might feel depleted and crave quiet time alone to recharge. This visceral experience reflects the underlying biological differences in how their brains process and react to external stimuli.

The distinction between introversion and extraversion extends beyond social preferences, manifesting in various aspects of life, including drug preference, communication styles, choice of workplace, and approaches to relationships. These differences are rooted in varying optimal levels of stimulation. Eysenck's arousal theory, further supported by research from Bullock and Gilliland (1993), suggests that introverts have chronically higher levels of cortical arousal, meaning their brains are naturally more active even in low-stimulus environments. In contrast, extraverts have chronically lower levels of cortical arousal, leading them to seek out more external stimulation to reach their optimal arousal level.

Consider a spectrum of stimulation, ranging from low (e.g., lying still in a dark, quiet room) to high (e.g., being yelled at by an angry mob). For an introvert, their optimal level of stimuli might be a quiet conversation with a familiar acquaintance. This level of interaction provides sufficient stimulation without overwhelming their already highly aroused nervous system. For an extravert, however, this same quiet conversation might be understimulating, leading them to seek out environments with louder music, more people, or more intense interactions to reach their preferred level of cortical arousal. Both introverts and extraverts are ultimately seeking an optimal level of brain activity, but they require different amounts of external stimulation to achieve it. An introvert's brain lights up more in response to the same stimulus compared to an extravert's brain. This means that a loud party, which might be exhilarating for an extravert, could be profoundly overwhelming and draining for an introvert, as their neural activity spikes significantly in response to the high sensory input. This fundamental difference in how their brains process and react to stimuli explains their divergent preferences and behaviors across various life domains.

Affect and Arousal

Before delving deeper into the biological underpinnings of personality and its connection to substance use, it is important to clarify two key terms: affect and arousal.

Affect: In psychology, affect refers to an emotion or feeling. It is the experience of emotion, such as joy, sadness, anger, fear, or interest. Affect is a subjective experience, but it can be expressed through observable behaviors, facial expressions, and physiological changes. When discussing personality, affect often refers to an individual's general emotional disposition or their tendency to experience certain types of emotions more frequently.

Arousal: Arousal refers to the level of physiological activation in the body and brain. It is a state of being awake, alert, and responsive to stimuli. Physiologically, arousal is reflected in various bodily responses, including heart rate, blood pressure, breathing rate, and neural activity in the brain. High arousal signifies a state of alertness and readiness for action, while low arousal indicates a state of relaxation or sleepiness. In the context of introversion and extraversion, arousal specifically refers to cortical arousal, or the level of activity in the brain's cerebral cortex. Understanding these terms is crucial for grasping the biological mechanisms that differentiate personality types and influence their interactions with substances.

Introversion-Extraversion: Biological Basis 

The profound differences observed between introverts and extraverts in their preferred levels of stimulation, energy restoration, and social engagement are not merely psychological constructs; they are rooted in distinct biological mechanisms. A compelling perspective on this biological basis comes from Desmond Morris's (1969) concept of the "stimulus struggle," drawing parallels from the animal kingdom. Morris categorized species into specialists and opportunists. Specialists thrive by having a highly efficient, specialized method for obtaining food, which reduces their need to explore diverse environments. Opportunists, conversely, have evolved to specialize in exploration, requiring high levels of environmental stimulation to thrive. Morris posited that humans, as opportunistic animals, also engage in a "stimulus struggle," seeking an optimal balance—not too much, but not too little—of stimulation. This inherent variability in the need for stimulation among humans, Morris suggested, manifests as introversion and extraversion.

This idea aligns with the observation that introverts and extraverts have chronically different levels of cortical arousal in response to stimuli. As previously noted, introverts exhibit higher baseline cortical arousal, meaning their brains are more active even in quiet environments. Consequently, they require less external stimulation to reach their optimal arousal level and can easily become overstimulated. Conversely, extraverts have lower baseline cortical arousal, necessitating more external stimulation to achieve their desired level of brain activity. This difference in preferred stimulus level explains their divergent choices in environments and activities, as both types are ultimately striving for a similar, comfortable level of cortical arousal. For instance, an introvert's brain might experience significant neural activity from a quiet conversation, while an extravert might need the intensity of a loud party to achieve the same level of internal "buzz."

Empirical evidence supports these physiological distinctions. Gray (1970) demonstrated that introverts show an increased brain-stem auditory evoked response (B.A.E.R.) to startling noises. In studies where participants were exposed to static noises of varying decibel levels, introverts consistently exhibited a stronger neural response—more neurons firing—to the same sound intensity compared to extraverts. This means that a car door slamming, or loud music at a party, literally causes more brain activity and a greater sense of overwhelm for an introvert. This heightened reactivity explains why introverts find high-stimulus environments more challenging and why they prefer quieter settings where their brains are not constantly bombarded by excessive sensory input.

The key neurological structure implicated in regulating cortical arousal is the Ascending Reticular Activation System (ARAS). The ARAS is a network of neurons located in the brainstem that connects the cerebral cortex to the rest of the brain. Often referred to as the "ignition system" of the brain, the ARAS is responsible for regulating overall arousal, wakefulness, and the filtering of sensory information. Damage to the ARAS can result in severe states of reduced consciousness, such as a coma, underscoring its critical role in maintaining alertness and responsiveness. The ARAS also plays a vital role in filtering out extraneous sensory information, allowing individuals to focus on relevant stimuli. For example, the constant tactile sensation of clothing on one's skin is typically filtered out by the ARAS, preventing sensory overload. Furthermore, the ARAS regulates sleep and wakefulness, with lower neuronal firing rates during sleep and higher activity levels during waking states. Its regulatory functions are mediated through various neurotransmitter systems, including GABAergic, adrenergic, and dopaminergic pathways, which influence neural activity and arousal levels.

In the context of introversion and extraversion, the ARAS functions differently. For introverts, their ARAS requires less stimulation to become overstimulated, leading to a rapid and significant increase in cortical arousal. This inherent sensitivity means that even moderate levels of external stimuli can quickly push an introvert's brain beyond its optimal arousal threshold, leading to feelings of being overwhelmed or drained. Conversely, extraverts require larger amounts of stimulation to activate their ARAS sufficiently, prompting them to actively seek out more stimulating environments and activities to achieve their desired level of cortical arousal. Recent research further supports this, showing that extraverts exhibit less brain activity in certain areas during memorization tasks and have lower resting brain activity when deprived of stimulation. This under-stimulation is a profoundly uncomfortable feeling for extraverts, driving their continuous pursuit of higher levels of external engagement.

This biological distinction profoundly influences various aspects of an individual's life. For instance, communication styles differ markedly. Extraverts tend to be more blunt, forceful, and prone to pushing social boundaries, such as using nicknames quickly or initiating physical touch, as these behaviors generate stimulating social feedback. Introverts, being chronically overstimulated, are more cautious and less inclined to engage in such boundary-pushing behaviors, as their brains are already working overtime. Workplace preferences also diverge; open-plan offices, designed for constant interaction and stimulation, are often ideal for extraverts but can be detrimental to introverts' cognitive functioning and memory due to sensory overload. Relationship approaches also reflect these differences, with extraverts often seeking broader social networks and introverts preferring deeper, more intimate connections.

Crucially, these biological differences in cortical arousal and ARAS functioning also impact drug preferences. Extraverts, with their chronically under-stimulated brains, tend to gravitate towards stimulants such as caffeine, cocaine, methamphetamine, and MDMA. These substances artificially increase neural firing and cortical arousal, helping extraverts achieve their desired level of internal stimulation. For them, a stimulant can make a quiet conversation feel more engaging or provide the "speed" they naturally crave. Conversely, introverts, who are often chronically overstimulated, tend to prefer depressants and anxiolytics. Substances like alcohol, benzodiazepines (e.g., Valium, clonazepam), and other GABAergic agonists literally slow down neural firing, reducing cortical arousal and helping introverts feel less overwhelmed, particularly in social environments. This allows them to function more comfortably in highly stimulating settings that might otherwise be unbearable. However, this preference also carries the risk of developing dependence on these substances to navigate everyday social interactions or to find solace in solitude, often leading to private and isolated patterns of substance use. Understanding this biological basis is paramount for developing targeted and effective interventions for substance use disorders, recognizing that different personality types may require distinct therapeutic approaches.

Extraversion & Substance Use

The inherent drive for stimulation in extraverted individuals creates distinct pathways to substance use, often mediated by social contexts and positive expectancies. Research consistently highlights several mechanisms through which extraversion is linked to substance abuse.

One significant mechanism is the social-amplification pathway. Extraverts are naturally drawn to social gatherings and environments that offer high levels of stimulation. These settings frequently involve alcohol and other substances, leading to increased exposure and opportunities for use. A longitudinal study of 1,200 first-year undergraduates, for example, found that high extraversion predicted earlier alcohol initiation and a greater number of drinking days throughout their freshman year (Geeraerts & Cooper, 2022). This suggests that the extravert's desire for social engagement and excitement places them in situations where substance use is prevalent, thereby amplifying their risk. Even though alcohol is a depressant, and extraverts generally prefer stimulants, the social context in which alcohol is consumed often provides the stimulating environment that extraverts seek. They are drawn to the party culture, the lively interactions, and the overall buzz of social events where alcohol is a common lubricant. This social aspect can override the physiological effects of alcohol as a depressant, making it appealing for its ability to facilitate social interaction and reduce social anxiety, particularly for extraverts who may also experience neurotic tendencies.

Another crucial mechanism is the positive-expectancy mechanism. Extraverts tend to hold stronger positive expectancies regarding the effects of alcohol and other substances. They anticipate that substance use will enhance their social experiences, increase pleasure, and reduce inhibitions, thereby facilitating the very social engagement they crave. A meta-analysis of 46 studies revealed that extraversion was significantly associated with stronger positive alcohol expectancies, and these expectancies fully mediated the frequency of heavy-episodic drinking (Kuntsche et al., 2021). This means that extraverts are more likely to believe that drinking will lead to desirable outcomes, which in turn drives their higher rates of consumption, particularly in binge drinking scenarios. The expectation of amplified positive social experiences fuels their engagement with substances.

Furthermore, there is a clear drug specificity linked to extraversion. Due to their chronically under-stimulated cortical arousal, extraverts exhibit a pronounced preference for stimulants. These substances, such as caffeine, cocaine, and methamphetamine, artificially increase neural activity, helping extraverts achieve their desired level of internal stimulation. A twin analysis, controlling for shared genetics, found that extraversion was uniquely linked to stimulant and cocaine use (Dash, Martin, & Slutske, 2023). This preference is not merely anecdotal; it is rooted in the biological drive to compensate for lower baseline brain activity. For an extravert, a stimulant can make an otherwise mundane situation feel more engaging and exciting, aligning with their inherent need for high levels of arousal. This explains why they might be more drawn to substances that "speed up" their internal experience, making social interactions and other activities feel more vibrant and stimulating.

It is also important to consider the interplay between extraversion and other personality traits, such as neuroticism. An individual can be a highly neurotic extravert, meaning they are outgoing and seek stimulation but also experience significant anxiety. In such cases, alcohol, despite being a depressant, can function as an anxiolytic, reducing their anxiety in social settings. This dual effect—providing social lubrication and anxiety reduction—can make alcohol particularly alluring, increasing the likelihood of binge drinking episodes. The combination of a desire for high stimulation and a need to manage anxiety can create a complex vulnerability profile for extraverted individuals.

Clinical & Treatment Implications for Extraversion

Understanding the unique characteristics of extraverted individuals has significant implications for tailoring effective clinical interventions for substance use disorders. Treatment strategies for extraverts should leverage their inherent social energy and desire for stimulation, while also addressing their specific vulnerabilities.

1. Leverage Social Energy: Extraverts thrive in environments that offer social interaction and engagement. Therefore, treatment approaches should actively incorporate group-based modalities. This includes group cognitive behavioral therapy (CBT), where the interactive nature of the setting can keep extraverts engaged and motivated. Peer-led recovery meetings, such as Alcoholics Anonymous (AA) or Narcotics Anonymous (NA), can be highly beneficial, as they provide a structured social environment and opportunities for connection. While AA generally works equally well for introverts and extraverts once engaged, extraverts may find the group dynamics and shared experiences particularly appealing, fostering a sense of belonging and accountability. Additionally, organizing "sober socials" or other pro-social, substance-free activities can provide extraverts with the stimulation and social connection they crave without the involvement of substances. These interactive activities can boost attendance and engagement in recovery programs.
2. Watch Party Culture and Protective Behavioral Strategies: Extraverts are often drawn to high-stimulation settings, such as parties, concerts, or sporting events, where substance use might be prevalent. Instead of advocating for complete avoidance of such environments, which may be unrealistic or unsustainable for some extraverts, it is crucial to teach protective behavioral strategies (PBS). These strategies aim to reduce the risks associated with substance use in high-stimulation settings. Examples include pacing drinks, alternating alcoholic beverages with water, setting limits on consumption, avoiding drinking games, and having a designated sober friend. For extraverts, who may get caught up in the excitement and social dynamics of these environments, learning how to navigate them safely is paramount to preventing binge drinking episodes.
3. Use Motivational Incentives: Extraverts are often driven by external rewards and recognition. Incorporating motivational incentives into treatment can significantly enhance their engagement and retention. This could involve public recognition boards for achieving sobriety milestones, offering leadership roles in after-care programs or peer support groups, or providing voucher incentives for adherence to treatment goals. Public acknowledgment and opportunities to lead can tap into an extravert's desire for dominance and social validation, keeping them motivated and invested in their recovery journey.
4. Address Relapse Triggers: For extraverts, common relapse triggers often include loneliness and boredom. When deprived of the external stimulation and social interaction they naturally crave, extraverts can experience significant discomfort and a strong urge to seek out substances as a means of alleviating this under-stimulation. Therefore, during early abstinence, it is critical to help extraverts schedule pro-social, substance-free activities. This proactive approach ensures that their need for engagement and connection is met through healthy outlets, reducing the likelihood of turning back to substances. Therapists should work with extraverted clients to identify and plan for periods of potential boredom or isolation, equipping them with a repertoire of alternative, stimulating activities.

While extraverts generally form rapport easily and are highly engaging in therapy, clinicians should be mindful of their potential for quick boredom. Therapy sessions, particularly those involving deep introspection or slow processing of emotions, might feel less stimulating than what an extravert is accustomed to. Therefore, therapists may need to employ more active, engaging techniques, incorporate varied activities, and maintain a dynamic pace to keep extraverted clients invested. The goal is to channel their natural drive for engagement and reward-seeking into the recovery process, transforming their inherent personality traits into assets for long-term sobriety.

Brain Asymmetry: Hemispheric Dominance and Personality

Beyond the broad dimensions of personality, a deeper understanding of individual differences can be found in the subtle yet significant variations in brain activity, particularly in the concept of brain asymmetry or hemispheric dominance. This area, however, has often been subject to popular misconceptions that warrant clarification. The notion of being "right-brained" (creative, emotional, holistic) versus "left-brained" (logical, verbal, analytical) is a sweeping generalization that lacks scientific accuracy. While certain functions, such as language production (e.g., Broca's area), are predominantly localized in one hemisphere, the brain functions as an integrated whole, with both hemispheres constantly communicating and collaborating. Therefore, it is crucial to distinguish scientific understanding from pop-psychology simplifications. This discussion will not delve into psychological interventions like Eye Movement Desensitization and Reprocessing (EMDR) or neurolinguistic programming, nor will it address outdated concepts of "masculine versus feminine hemispheres."

Instead, brain asymmetry, in a scientifically grounded context, refers to the quantifiable differences in activation levels between the right and left sides of the brain, typically measured through techniques like electroencephalography (EEG). This difference is often expressed as a numerical value: a negative number indicates higher activity on the left side of the brain, while a positive number indicates a higher degree of activity on the right side of the brain. These differences, even at rest, have been found to predict an individual's emotional disposition. Specifically, research has shown that individuals with greater right frontal EEG activity (positive asymmetry) tend to exhibit more pessimistic emotional dispositions. Conversely, those with greater left frontal EEG activity (negative asymmetry) are often characterized by more upbeat or optimistic emotional dispositions.

Further research has refined this understanding by examining brain asymmetry in response to emotional stimuli. When participants were exposed to films designed to elicit specific emotions, individuals with higher left hemisphere activity were more responsive to positive mood films, experiencing and expressing more positive affect. Conversely, those with higher right hemisphere activity showed greater responsiveness to negative mood films, indicating a heightened sensitivity to distressing emotions. This suggests that hemispheric dominance is not merely a static state but influences how individuals process and react to emotional information from their environment.

The initial understanding of total differences in hemispheric dominance was limited by the sensitivity of older EEG technology, which could not pinpoint specific brain regions with precision. However, advancements in neuroimaging have allowed researchers to describe these differences more accurately in terms of approach and avoidance emotional tendencies. This refined perspective posits that distinct neural circuits are responsible for motivating behavior towards desired outcomes (approach) and away from undesired ones (avoidance).

Specifically, left hemisphere activity is associated with approach behaviors and emotions. This includes emotions such as joy, interest, and even anger (when anger is directed towards overcoming an obstacle or achieving a goal). The left prefrontal cortex, in particular, is linked to the Behavioral Activation System (BAS), which drives individuals towards incentives and rewards.

In contrast, right hemisphere activity is associated with avoidance behaviors and emotions. This includes emotions such as distress, disgust, and fear, which motivate withdrawal from perceived threats or negative stimuli. The right prefrontal cortex is linked to the Behavioral Inhibition System (BIS), which is responsible for inhibiting behavior in the face of potential punishment or danger.

This shift in understanding from broad hemispheric dominance to specific approach and avoidance systems provides a more nuanced and clinically relevant framework for understanding how brain asymmetry influences personality and, by extension, vulnerability to substance use disorders. It highlights that emotional disposition is not simply about being generally "positive" or "negative," but rather about the relative strength of one's motivational systems for engaging with or withdrawing from the world.

BIS/BAS: Behavioral Activation System and Behavioral Inhibition System

The Behavioral Inhibition System (BIS) and the Behavioral Activation System (BAS) represent two fundamental neurobiological systems that underpin individual differences in motivation, emotion, and behavior, offering a powerful framework for understanding personality pathways to substance use. These systems, rooted in brain asymmetry, govern an individual's sensitivity to cues of punishment versus reward.

The Behavioral Inhibition System (BIS) is a neurological system in the brain that is primarily responsible for causing individuals to withdraw from undesirable stimuli or potential threats. It is associated with vigilance, anxiety, and a tendency to inhibit ongoing behavior in the face of punishment or non-reward. Individuals with a highly active BIS are more sensitive to cues of punishment and tend to experience emotions like distress, disgust, and fear. Self-reports of high BIS sensitivity are correlated with higher activity levels in the right frontal area of the brain, particularly the right prefrontal cortex. This system is thought to involve serotonin activity, which plays a role in modulating mood and anxiety. Greater BIS activity is characteristic of introversion, neuroticism, and low agreeableness, as these traits are often associated with caution, emotional reactivity to negative stimuli, and a tendency to avoid social conflict or perceived threats.

Conversely, the Behavioral Activation System (BAS) directs individuals toward certain desirable goals or incentives. It is responsible for approach emotions such as joy, interest, and even anger when it serves as a motivator to overcome obstacles. Individuals with a highly active BAS are more sensitive to cues of reward and tend to pursue goals vigorously. Self-reports of high BAS sensitivity are correlated with higher activity levels in the left frontal area of the brain, particularly the left prefrontal cortex. This system is strongly linked to dopamine activity, a neurotransmitter crucial for reward processing and motivation. Greater BAS activity is characteristic of extraversion and openness to experience, as these traits are associated with a drive for novelty, social engagement, and a general pursuit of positive experiences.

It is important to understand that BIS and BAS sensitivities are not mutually exclusive; an individual can be high in both, low in both, or high in one and low in the other. Temperament differences often emerge as a relative balance between positive affect/approach behaviors (BAS) and negative affect/inhibition behaviors (BIS).

• BAS sensitivity (Dornbach-Bender et al., 2020) magnifies an individual's reactions to positive events and correlates with higher self-reported positive affect. These individuals are highly responsive to rewards and are motivated by the anticipation of pleasure.
• BIS sensitivity (Lin et al., 2023) magnifies an individual's reactions to negative events and is strongly related to neuroticism. These individuals are highly responsive to potential punishments and are motivated by the avoidance of pain or negative outcomes.

The interplay of these systems can explain various psychological difficulties:

• Anxiety: Often indicative of an oversensitive BIS activity, where individuals are excessively vigilant to potential threats and prone to worry and avoidance behaviors.
• Depression: Can be associated with high BIS activity (increased sensitivity to negative experiences) coupled with weak BAS activity (reduced motivation to pursue rewards and experience pleasure).
• Antisocial personality: Often characterized by high BAS activity (strong drive for reward and sensation-seeking) combined with low BIS activity (weak responsiveness to punishment or negative consequences), leading to impulsive and reckless behaviors without sufficient inhibition.

Understanding the relative strengths of an individual's BIS and BAS provides a powerful lens through which to view their vulnerability to substance use disorders and to tailor interventions more effectively.

BIS/BAS and Substance-Use Disorders

The Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS) framework provides a robust explanation for distinct pathways to substance use disorders, influencing drug preference, craving, and relapse patterns. The differential sensitivity to reward and punishment cues, mediated by these systems, plays a critical role in shaping an individual's relationship with substances.

High BAS (Reward Sensitivity): Individuals with a highly active BAS are inherently more sensitive to cues of reward and are driven by the pursuit of pleasure and positive experiences. This heightened reward sensitivity has been consistently linked to various aspects of substance use. Research indicates that high BAS is associated with earlier initiation of substance use, higher frequency of use, and greater polysubstance involvement (Loxton & Dawe, 2001; Keough & O’Connor, 2014). This is particularly true for stimulants and alcohol. Stimulants, by their very nature, directly activate the brain's reward pathways, providing the intense positive reinforcement that high BAS individuals crave. Alcohol, while a depressant, is often consumed in social, stimulating environments that offer immediate rewards (e.g., social connection, reduced inhibition), making it appealing to those driven by BAS.

Furthermore, a BAS-dominant profile strongly predicts stronger cue-induced craving and rapid reinstatement after abstinence (Franken & Muris, 2006). This means that individuals with a high BAS are more likely to experience intense cravings when exposed to environmental cues associated with substance use (e.g., seeing a bottle of alcohol, being in a place where they used to use). Their strong drive for reward makes them highly susceptible to these triggers, leading to a quicker return to substance use even after periods of abstinence. The anticipation of pleasure and the memory of past rewards associated with the substance exert a powerful pull, making sustained recovery challenging without targeted interventions.

High BIS (Punishment Sensitivity): Conversely, individuals with a highly active BIS are more sensitive to cues of punishment, threat, and negative emotional states. Their motivation is often driven by the desire to avoid pain, anxiety, or discomfort. This heightened punishment sensitivity influences their drug preference, leading them towards substances that dampen negative affect. High BIS sensitivity is associated with a preference for anxiolytic or depressant drugs, such as opioids and benzodiazepines (e.g., Valium, Xanax), and alcohol (Simons, Wills, & Gibbons, 2009). These substances provide a sense of calm, reduce anxiety, and alleviate emotional distress, offering a temporary escape from the discomfort associated with an overactive BIS. For these individuals, substance use is often a form of self-medication, a means to quiet an agitated internal state or to cope with overwhelming negative emotions.

Moreover, a BIS-dominant profile is strongly associated with relapse under stress or social threat, mediated by worry and avoidance coping (Keough & O’Connor, 2014). When faced with stressful situations, interpersonal conflicts, or perceived social threats, individuals with a high BIS are more likely to experience intense anxiety and engage in avoidance behaviors. Substance use becomes a readily available coping mechanism to escape these uncomfortable feelings, even if it leads to long-term negative consequences. The cycle of stress, anxiety, avoidance, and substance use can be particularly entrenched for BIS-dominant individuals, making stress management and anxiety-focused strategies crucial components of their treatment.

In summary, the BIS/BAS framework highlights that substance use is not a monolithic phenomenon but rather a multifaceted issue driven by distinct motivational pathways. High BAS individuals are drawn to substances for their rewarding, pleasure-enhancing effects, leading to a focus on approach-based motivations. High BIS individuals, on the other hand, are drawn to substances for their anxiety-reducing, pain-dampening effects, driven by avoidance motivations. Recognizing these differential sensitivities is paramount for clinicians to develop personalized and effective treatment strategies that address the unique underlying motivational drivers of each client's substance use disorder.

BIS/BAS-Informed Treatment Implications

The insights derived from the Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS) framework offer invaluable guidance for tailoring treatment interventions for substance use disorders. By understanding a client's predominant motivational system—whether they are primarily driven by reward seeking (BAS) or punishment avoidance (BIS)—clinicians can design more effective and personalized therapeutic strategies.

For High BAS Clients (Reward Sensitivity):

High BAS clients, characterized by their strong drive for reward and sensitivity to incentives, respond best to approach-based interventions that emphasize immediate gains and positive reinforcement.

1. Contingency Management: This is a highly effective approach for high BAS individuals. It involves providing tangible rewards (e.g., vouchers, privileges) for desired behaviors, such as negative drug tests or attendance at treatment sessions. The immediate and consistent reinforcement directly taps into their reward-seeking motivation, making abstinence and treatment adherence more appealing.
2. Voucher Incentives: Similar to contingency management, voucher programs offer monetary or other valuable incentives that can be exchanged for goods or services. This provides a clear, tangible reward system that aligns with the BAS drive for positive outcomes.
3. Goal-Oriented Cognitive Behavioral Therapy (CBT): CBT approaches that frame abstinence as an immediate gain, focusing on the positive rewards of sobriety (e.g., improved health, better relationships, financial stability), are particularly effective. This involves helping clients identify and pursue new, healthy goals that provide a sense of accomplishment and reward, replacing the gratification previously sought from substances.
4. Tailoring Motivational Interviewing Frames: "Possible Selves" (BAS-focused): In motivational interviewing, clinicians can leverage the concept of "possible selves" to highlight a rewarding future self. For high BAS clients, this means emphasizing the "thriving sober self"—a future where they experience increased joy, success, social connection, and personal fulfillment as a direct result of abstinence. This positive vision taps into their intrinsic motivation for reward and achievement.
5. Integrating BIS/BAS Assessments: Utilizing assessments like the Carver-White scale at intake can provide valuable information about a client's BIS/BAS profile. This allows for improved treatment-matching and has been shown to predict treatment retention (Daughters et al., 2008). Knowing a client's motivational tendencies from the outset enables clinicians to select interventions that are most likely to resonate and be effective.

For High BIS Clients (Punishment Sensitivity):

High BIS clients, who are more sensitive to punishment and driven by the avoidance of negative emotional states (like anxiety), benefit most from anxiety-focused strategies that reduce punishment expectancy and provide effective coping mechanisms for distress.

1. Mindfulness: Mindfulness-based interventions, such as Mindfulness-Based Relapse Prevention (MBRP), are highly beneficial. These practices help clients develop a non-judgmental awareness of their internal experiences, including cravings and anxiety, without being overwhelmed by them. By observing thoughts and feelings without reacting impulsively, clients can reduce their reliance on substances as an avoidance strategy. Mindfulness helps to lower craving and improve emotional regulation, offering a quiet coping skill that aligns with an introvert's preference for less external stimulation.
2. Exposure Plus Relaxation: This therapeutic technique involves gradually exposing clients to anxiety-provoking situations or cues (e.g., places where they used to use, stressful social scenarios) while simultaneously teaching and practicing relaxation techniques. This helps to reduce the conditioned fear response and build tolerance to discomfort without resorting to substance use. It directly addresses the avoidance motivation characteristic of high BIS individuals.
3. Safety-Planning: Developing comprehensive safety plans helps high BIS clients identify potential triggers for anxiety and relapse and pre-plan concrete strategies to manage these situations without using substances. This reduces the uncertainty and perceived threat, thereby decreasing punishment expectancy and enhancing their sense of control.
4. Tailoring Motivational Interviewing Frames: "Possible Selves" (BIS-focused): For high BIS clients, motivational interviewing can emphasize the "feared future self" or a "rock-bottom" scenario. This approach leverages their avoidance motivation by highlighting the negative consequences of continued substance use (e.g., health deterioration, loss of relationships, financial ruin). By vividly contrasting their current struggles with a potentially worse future, clinicians can motivate clients to pursue abstinence as a means of avoiding these feared outcomes (Simons et al., 2009).
5. Individualized and Smaller Group Therapies: Introverts, who often characterize high BIS profiles, tend to have a slower alliance formation in therapy. Building rapport and disclosing intimate details can be highly stimulating and overwhelming for them. Therefore, one-on-one motivational interviews or cognitive behavioral therapy in small groups (rather than large ones) are often more effective. In larger groups, extraverts may dominate, causing introverts to withdraw and limit their disclosure, thereby hindering their therapeutic progress. The increased availability of telehealth services, particularly since the pandemic, has also proven beneficial for naturally introverted individuals, allowing them to engage in therapy from the comfort of their own environment, reducing external stimulation.

By integrating BIS/BAS assessments at intake and tailoring interventions accordingly, clinicians can significantly improve treatment-matching and predict retention rates. This personalized approach acknowledges the unique motivational landscape of each client, fostering greater engagement and ultimately leading to more successful and sustainable recovery outcomes.

Conclusion

The journey through the intricate pathways connecting personality to substance use disorders reveals a profound and multifaceted relationship. It underscores that vulnerability to addiction is not a monolithic phenomenon but rather a complex interplay of innate temperament, learned behaviors, and underlying neurobiological systems. By delving into the Big Five personality traits, with a particular focus on extraversion and introversion, and the Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS) framework, this article has illuminated how individual differences shape drug preferences, patterns of use, and responsiveness to therapeutic interventions.

We have seen that personality, as the dynamic outcome of temperament interacting with environmental influences, provides a consistent lens through which to understand an individual's behavioral patterns across time and situations. The Big Five model—encompassing Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism—offers a comprehensive yet succinct framework for categorizing these enduring traits. While each trait contributes uniquely to an individual's risk profile, the dimensions of extraversion and introversion stand out due to their direct links to cortical arousal and the pursuit or avoidance of stimulation.

The biological basis of introversion and extraversion, particularly the role of the Ascending Reticular Activation System (ARAS) in regulating cortical arousal, provides a compelling explanation for divergent preferences. Extraverts, with their chronically under-stimulated brains, gravitate towards stimulants and high-stimulation environments, seeking to elevate their arousal to an optimal level. Their social-amplification and positive-expectancy pathways often lead to earlier initiation and higher frequency of substance use, especially alcohol and stimulants, within social contexts. Conversely, introverts, with their chronically higher baseline arousal, prefer depressants and quieter environments, using substances to dampen overwhelming neural activity and cope with anxiety or social overstimulation.

The BIS/BAS framework further refines this understanding, distinguishing between approach-motivated (BAS) and avoidance-motivated (BIS) individuals. High BAS sensitivity predicts a preference for rewarding substances and a heightened risk of cue-induced craving and relapse driven by the pursuit of pleasure. High BIS sensitivity, on the other hand, is linked to a preference for anxiolytic substances and a greater susceptibility to relapse under stress, driven by the desire to alleviate discomfort and avoid negative emotions.

The clinical implications of this knowledge are profound. Recognizing a client's predominant personality traits and motivational systems allows for the tailoring of interventions, moving beyond a one-size-fits-all approach. For extraverted, high BAS clients, strategies that leverage their social energy, provide positive incentives, and teach protective behavioral strategies in stimulating environments are crucial. Group therapies, peer-led recovery, and goal-oriented CBT that frames abstinence as immediate gain can be highly effective. For introverted, high BIS clients, anxiety-focused strategies, mindfulness, exposure with relaxation, and safety planning are paramount. Individualized therapy or smaller group settings, where they feel less overwhelmed, are often more conducive to building rapport and facilitating disclosure. Tailoring motivational interviewing to emphasize either "thriving sober selves" (for BAS) or "feared future selves" (for BIS) can further enhance engagement.

Ultimately, integrating personality assessments and principles into substance abuse treatment fosters a more empathetic, nuanced, and effective approach. By understanding the unique internal landscape of each client—their inherent drives, sensitivities, and coping mechanisms—clinicians can develop personalized pathways to recovery that resonate with the individual, enhancing treatment retention and promoting long-term sobriety. This holistic perspective not only improves clinical outcomes but also deepens our appreciation for the rich tapestry of human diversity in the journey towards healing.

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Additional Current References

Please Note: The following resources have been included as additional resources associated with this topic area. These resources were not used by the presenter when creating this course.

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