Running Header: SUBSTANCE USE, PERSONALITY, & GENDER AMONG A CLINICAL SAMPLE Substance Use in a Clinical Sample: The Importance of Personality and Gender

The purpose of our study was to examine the role of the big five personality traits in explaining substance use disorders (SUDs) among a clinical sample. High rates of comorbidity indicate that psychiatric patients are vulnerable to SUDs. However, most previous studies on personality and SUDs have focused on community samples. Our aim was to investigate the extent to which findings from previous research on personality and SUDs can be extrapolated onto a psychiatric population. We also explored the stability of these relations according to gender, and among specific drug categories. Our sample consisted of 764 psychiatric patients from the MacArthur Violence Risk Assessment Study. Personality traits were assessed using the NEO-Five Factory Inventory. SUDs were based on patients’ clinical diagnosis of lifetime drug dependence. Specific drug use was evaluated according to whether or not patients with SUDs ever used particular drugs more than five times. Using logistic regression, we examined the relationship between personality and gender interactions in explaining SUDs. Further analysis was also conducted according to specific drug categories to determine whether the traits that predict SUDs remain stable across different drugs of abuse. The results indicated that the personality traits of Agreeableness and Conscientiousness were inversely related to any SUDs. Openness to Experience was positively related to the use of hallucinogenic substances. Gender differences in the traits that predicted substance use were most evident for hallucinogenic substance use. Our findings were similar to previous research on personality and SUDs among community populations, in that the traits of Agreeableness and Conscientiousness were found to be inversely related to SUDs among a psychiatric population. The trait of Neuroticism was not found to be related to SUDs among our sample, which is in contrast to research on community substance users. This suggests that psychiatric substance users did not differ in terms of this trait compared to other psychiatric patients without SUDs. Slight gender differences and heterogeneity across drug categories were found, however more research in this area is needed in order to ensure that our findings were not sample specific. Despite this, the results of our study imply that previous research on personality and SUDs in community populations can be extended onto psychiatric populations. SUBSTANCE USE, PERSONALITY, & GENDER AMONG A CLINICAL SAMPLE 3 Substance use is a complex issue that has negative implications on the wellbeing of the individual and the society. According to the Canadian Mental Health Association, substance use becomes a diagnosable disorder when the behavior becomes impulsive and creates life problems (CMHA, 2005). The Epidemiological Catchment Area Project, which surveyed over 20,000 U.S. citizens from five sites found the prevalence of substance use disorders (SUDs) to be around six percent, with half of these individuals experiencing concurrent mental illnesses (Regier et al., 1990). Individuals with concurrent psychiatric and substance use disorders are referred to as having dual diagnoses (Solomon et al., 1993). Patients with dual diagnoses often initially experience the SUDs and mental illness independently; however, over time the disorders tend to interact and exacerbate the associated problems (Solomon et al., 1993). The health-related and social costs of substance use have spurred on a great deal of research attention on the subject; however, research on SUDs in psychiatric populations has been limited. The goal of the present study was to examine some factors that underlie the problem of dual diagnosis in a clinical population. Research on substance use indicates several factors that may predispose individuals to the onset and maintenance of SUDs. These include inherent features such as biologicallyinformed personality traits, neurobiology, and cognitive-affective regulation; and external factors such as environment, culture, and other situational contexts (Lubman et al., 2004). Among these factors, many researchers have been interested in the role of personality in particular, and have accorded personality traits a central role for the understanding of SUDs (McGue et al., 1999). Conway (2002) suggests that personality may be predictive of SUDs because personality traits precede the onset of substance misuse (Conway et al., 2002). As such, an examination of the associations between personality dimensions and SUDs may SUBSTANCE USE, PERSONALITY, & GENDER AMONG A CLINICAL SAMPLE 4 provide useful insight to the underlying nature of the disorder (Krueger et al., 1996; McGue et al., 1999; Ball, 2005). Personality can be defined by a set of traits that organize the individual’s mental system, and develop to become stable over time and consistent across situations (Piedmont, 1998). Theory proposes that the link between personality characteristics and substance-related behavior may be mediated by different reinforcement processes (Wise, 1988; Comeau et al., 2001; Woicik et al., 2009). The consumption of psychotropic substances is associated with various negative and positive reinforcement effects (Wise, 1988). Negative reinforcement refers to symptomatic relief that the individual experiences through the use of the substance. It is suggested that some individuals may have personality traits that motivate them to use drugs as a way of coping with their problems and self-regulation (Comeau et al., 2001; Woicik et al, 2009). For instance, neurotic personality traits such as a proneness to anxiety and depression have been found to be correlated with SUDs via a negative reinforcement pathway (Comeau et al., 2001; Woicik et al, 2009). At the same time, certain psychotropic substances have positively reinforcing effects that are associated with an enhancement of affect (Comeau et al., 2001; Woicik et al, 2009). Researchers have found personality traits such as sensation-seeking, the desire for new experiences, and impulsivity to be associated with the positive reinforcement pathway to SUDs (Comeau et al., 2001; Woicik et al, 2009). As such, personality traits may be an effective indicator of individuals who are more susceptible to SUDs via specific reinforcement pathways. Several theories have also been developed to explain the relationship between SUDs and psychiatric disorders among dual diagnosis populations. The signal hypothesis holds that the excessive misuse of substances is a sign of distress, and the comorbidity with other psychological problems acts as testimony to the validity of this hypothesis (Segrin, 2001). Another more prominent theory is the self-medication hypothesis; this suggests that SUBSTANCE USE, PERSONALITY, & GENDER AMONG A CLINICAL SAMPLE 5 individuals use substances as a compensatory way of modulating affect and self-soothing the distress caused from the psychiatric disorder (Khantzian, 2008; Gandhi et al., 2003). The selfmedication hypothesis falls in line the previously discussed negative reinforcement pathways that mediate between personality and substance misuse (Comeau et al., 2001). Although some personality traits may predict an increased risk of SUDs among psychiatric populations, there has been a lack of research examining this among those with dual diagnoses. Since most studies have focused on personality traits and SUDs among non-psychiatric populations, it would be worthwhile to explore the extent to which this information maps onto a dual diagnoses sample. Recent studies on personality and SUDs have used comprehensive assessment approaches in the evaluation of traits related to substance use. The NEO Five Factor Inventory (NEOFFI) has numerous strengths with regards to reliability and validity in cross-cultural, clinical and community samples (Ball, 2005; Piedmont & Ciarrocchi, 1999; Carter et al., 2001). The NEO-FFI evaluates five super-ordinate personality domains of Neuroticism (N), the tendency to experience negative emotions, Extraversion (E), the inclination to social stimulation, Openness to Experience (O), the willingness to try new things, Agreeableness (A), the dimension of interpersonal relations, and Conscientiousness (C), the tendency to be organized and reliable (Piedmont, 1998; Terracciano et al., 2008). These five traits offer a useful summary of personality dispositions for clinicians and researchers of SUDs, and the information gathered using the NEO-FFI may also be useful for the planning of intervention, treatment, or prevention of the disorder (Miller, 1991; Piedmont, 1998, Trull & Sher, 2004). The NEO-FFI yields information about personality that may be useful for the matching of treatments to persons with SUDs. A qualitative study by Miller (1991) provided insight into how individuals who score high or low on each personality domain might respond to therapy (Miller, 1991). According to Miller, individuals with high N typically experience difficulties SUBSTANCE USE, PERSONALITY, & GENDER AMONG A CLINICAL SAMPLE 6 in mood and anxiety regulation, and may engage in self-defeating behaviors like substance use. Consequently, intervention programs for high N clients should be directed towards addressing the client’s emotional distress (Miller, 1991). The personality trait of E was found to be positively correlated with treatment outcomes (Miller, 1991). Correspondingly, Ball (2005) found that patients with low E were prone to social and psychological withdrawal that may ultimately hinder treatment progress (Ball, 2005). Individuals with high degrees of O are more likely to respond positively to novel treatment methods, whereas those with low levels of O typically prefer more conventional therapy styles (Miller, 1991). With regards to the domain of A, Miller highlighted that low A clients were more predisposed to interpersonal antagonism and skepticism of treatment, and high A clients had difficulties in the area of decision-m