Conceptualizing impulsivity and risk taking in bipolar disorder: Importance of history of alcohol abuse

Individuals with bipolar disorder (BD) tend to be impulsive and engage in risky behaviors—pleasurable activities with high potential for negative consequences. Indeed, increased risk taking is one of several diagnostic criteria for a manic episode (1). Impulsivity can be conceptualized as a personality trait, characterized by acting quickly and without planning in order to satisfy a desire (2). As such, impulsivity is a complex, multifaceted construct that includes cognitive components, personality / motivational dimensions, and behavioral components; related traits and behaviors include risk taking, sensation seeking, and behavioral disinhibition (3, 4). Among the most popular self-report indices of impulsivity is the Barratt Impulsiveness Scale (BIS) (5), which incorporates three dimensions of impulsivity: attentional, motor, and non-planning. Based on research with this instrument, there is growing evidence that impulsivity is a stable trait characteristic of BD (6) and appears to represent a core feature of the illness (7). Elevated levels of impulsivity have been found in BD patients during manic (8, 9), depressive (10), and euthymic (9, 10) periods. Additionally, increased impulsivity has been linked to a more severe suicide attempt history in BD (11). Impulsivity and risk-taking propensity are thought to be highly correlated, yet not synonymous, constructs. Elevated levels of impulsivity are often present among those psychiatric disorders characterized by risk-taking behavior (e.g., bipolar disorder, personality disorders, and substance use disorders) (12). In general, impulsivity refers to a predisposition and an overall pattern of behavior, whereas risk taking encompasses specific, situationally determined behaviors that may or may not result from a deficit in impulse control (2). Although risk taking is often part of the clinical presentation of BD, very few studies have formally assessed risk-taking propensity in BD patients. A better understanding of the relationship between impulsivity and risk-taking behavior in BD has implications for the development of appropriate treatment strategies. Impulsivity and risk taking are also constructs of central importance for addictive disorders. For example, higher levels of impulsivity are seen in early-onset versus late-onset alcoholics (13). Increased impulsivity has also been associated with early experimentation with illicit substances and a high susceptibility to developing substance use disorders (14). One commonly used behavioral measure of risk taking in research related to addictive disorders is the computerized Balloon Analogue Risk Task (BART) (15). Numerous studies have found performance on the BART to be related to self-report of substance use and other risk behaviors (15–19). To our knowledge, this is the first study to apply this task in patients with BD. An estimated 56% of patients with bipolar I disorder experience alcohol abuse and 38% experience alcohol dependence during their lifetimes (20). There is increasing evidence that alcoholism phenomenologically changes illness presentation in bipolar disorder and can lead to increased chronicity and symptom severity [see (21) for a review]. Because problems with alcohol use are so common in BD, any conceptualization of impulsivity and risk taking in BD must include an understanding of the effect of comorbid alcohol use disorders. In the current study, we used the BIS and the BART to better conceptualize impulsivity and risk propensity, respectively, in patients with BD with and without a history of alcohol use disorders. Based on the existing literature, we predicted that patients with BD overall would have elevated levels of both impulsivity and risk taking compared to demographically matched healthy control (HC) subjects. Additionally, we expected patients with BD with a history of alcohol abuse or dependence (BD-A) to have exaggerated levels of impulsivity and risk taking compared to their counterparts without a history of alcohol abuse or dependence (BD-N). Further, consistent with the notion that these measures reflect trait dimensions of BD, we predicted that performance would not be related to clinical symptoms.