Interactive Effects of Cumulative Stress and Impulsivity on Alcohol Consumption

The influence of environmental factors such as stress and individual difference traits such as impulsivity on the development and course of alcohol dependence are well established in both human and animal literature (Evenden, 1999a; Sinha, 2008). Neuroadaptations to stress systems have been shown to underlie the pathophysiology of alcohol, as well as stimulant, opioid, and nicotine addiction (Fox and Sinha, 2009 for review). Well-established human models of addiction such as stress-coping (Wills and Shiffman, 1985) and relapse prevention models (Marlatt and Gordon, 1985) have also presented problem drinking as a maladaptive coping response to life stressors. In addition, both animal and human studies have shown that impulsivity, in terms of impulsive choice and inhibitory failure, is also paramount to the acquisition and escalation of alcohol and substance abuse (Perry and Carroll, 2008 for review). Although both stress and impulsivity are independent risk factors for drinking, few studies have investigated the nature of their interactive relationship in terms of harmful and hazardous drinking patterns. The interactive nature of stress regulatory mechanisms on drinking is highlighted by genetic research investigating the impact on drinking of various levels of life adversity and genetic markers implicated in regulatory behavior. For example, young adults exposed to high levels of psychosocial adversity and carrying the long variant of the serotonin transporter gene exhibit greater hazardous drinking compared with those carrying the short allele or not exposed to high levels of adversity (Laucht et al., 2009). This serotonin transporter gene polymorphism has also been shown to interact with rearing stress in nonhuman primates (Barr et al., 2004) as well as stressful life events in adolescents and young adults (Covault et al., 2007; Kaufman et al., 2007; Olsson et al., 2005) with regard to increased drinking patterns and greater nonprescription dug use. While these studies have assessed genetic markers linked to behaviors associated with impulsivity (Paaver et al., 2007; Wagner et al., 2009), a more direct relationship between various aspects of subjective trait impulsivity and cumulative life stress on problem drinking behaviors have not been evaluated within a local community sample of volunteers. Therefore, current study examines the relationship between various types of stress and different aspects of impulsivity on alcohol use and alcohol-related problems as assessed by the Alcohol Use Disorders Identification Test (AUDIT; Babor et al., 2001). Both epidemiological and clinical research has indicated that recent life stress (Perkins, 1999; Rutledge and Sher, 2001), cumulative adverse life events, including life traumas (Lloyd and Turner, 2008; Turner and Lloyd, 2003), and traumatic life experiences (Breslau et al., 2003; Reed et al., 2007) have all been positively associated with increases in drinking and substance abuse. However, diverse types of stress may differentially affect biopsychological markers associated with drinking vulnerability, showing certain stressors to be stronger indicators of problem drinking than others. For example, while traumatic or enduring stress has been associated with reduced cortisol response to stress exposure (Geracioti et al., 2008), daily stress has been associated with increased cortisol activity (Brantley et al., 1988; Roy et al., 2003;). Similarly, heart rate variability (HRV) and dopamine (DA) neurotransmission have also been shown to differ with regard to whether stressors are acute or chronic (Farah et al., 2004; Kalivas and Duffy, 1995; Lucas et al., 2004). In the current study, we use a comprehensive cumulative stress measure adapted from Turner and Wheaton (1995) to assess recent adverse life events as well as cumulative traumatic stress, major life events, and chronic stress. Similarly, impulsivity is a multidimensional construct (Evenden, 1999b; de Wit, 2009) defined in the literature by a wide range of paradigms (Evenden, 1999a for review). In general, however, behavioral studies have indicated that impulsive choice (or failure to delay gratification) and response inhibition are most relevant to the transition from controlled to compulsive drinking (Evenden, 1999a; Perry and Carroll, 2008; Rubio et al., 2007). In the current study, we use the BIS-11 (Patton et al., 1995) a widely used and well standardized measure of impulse control likely to provide a reliable subjective index of these regulatory processes. While the Nonplanning subscale of the BIS has been associated with performance on delayed discounting tests as both may reflect an insensitivity to future gratification (de Wit et al., 2007), the Attention and Motor subscales have been shown to correlate with inhibitory control-related tasks including Go No Go and Trails B (Asahi et al., 2004; Keilp et al., 2005; Spinella, 2007). We therefore aim to assess the effects of life adversity and trait impulsivity on alcohol use and alcohol-related problems, as measured by the AUDIT in a community sample. Establishing the nature and relative contribution of both stress and impulsivity to at-risk drinking within a community sample will help determine better tailored intervention programs focused on prevention and the progression of alcohol abuse.