Does impulsivity help in understanding the relationship between social anxiety and alcohol use disorders?

Social anxiety disorder (SAD) and alcohol use disorders (AUDs) are highly prevalent diagnoses which co-occur at a high rate within clinical and epidemiological populations. Studies concur that the high rates of comorbidity between social anxiety and alcohol use disorders are related to increased chronicity and severity, poorer quality of life, and less effective treatment outcomes. Although the relationship between social anxiety and alcohol use disorders has been the subject of extensive exploration, previous studies have failed to draw consistent conclusions about the direction and nature of this relationship. Understanding and delineating factors that underlie this relationship are important precursors to effective diagnosis and treatment, and individual variables such as impulsivity have recently been considered in the literature as a factor that may impact this relationship. Thus, the aim of this thesis was to empirically evaluate impulsivity as a contributor to the comorbidity between social anxiety and alcohol use disorders; to better understand the risk and maintenance factors involved in this relationship. The relationship between social anxiety and alcohol use disorders was investigated empirically using both clinical, non-clinical, treatment-seeking and non treatment-seeking samples, and employing optimal experimental methodologies. Four separate studies were conducted: The first examined the rates of alcohol use disorders and the impact of alcohol use and drinking behaviours on outcomes for treatment targeting social anxiety disorder, and showed how planned alcohol consumption prior to social situations and drinking during social situations are associated with more severe social anxiety symptoms. The second investigated the role of a two-factor model of impulsivity using both trait and behavioural measures—to differentiate between dependent and non-dependent drinkers with, and without, comorbid social anxiety—and found that both components are useful in differentiating between those with, and without, this comorbidity. The third examined the physiological and subjective responses to alcohol ingestion and perceived intoxication, and their association with impulsivity and alcohol expectancies, in a treatment-seeking sample of individuals with comorbid social anxiety disorder and alcohol problems, and revealed how impulsivity and social anxiety may maintain problematic drinking via two pathways involving the subjective and physiological effects of alcohol. The role of alcohol expectancies was observed to be less influential in regulating responses to alcohol cues. The final study explored whether impulsivity influenced social anxiety and alcohol treatment outcomes in individuals with comorbid social anxiety and alcohol use disorders. This study found that higher impulsivity was related to more severe social anxiety and alcohol dependence initially, but also a greater reduction in these symptoms following treatment. These findings highlight that understanding the impact of impulsivity on treatment targeting these problems may have prognostic utility and suggests that these individuals may benefit from a well structured therapeutic approach. Taken together, these studies advance our understanding of the relationships between these highly comorbid disorders that can have a severe impact on quality of life. Understanding these relationships is essential because in order to decrease comorbidity and the problems associated with it, we must first understand the risk and maintenance factors involved in the relationship. This body of work contributes to the literature by using a contemporary two factor model of impulsivity to extend our knowledge about the co-occurrence between social anxiety and alcohol use problems. Specifically, how two components of impulsivity, reward drive and rash impulsivity, relate to who develops SAD-AUD comorbidity, how these problems are maintained, and how individuals with these problems respond to treatment interventions.