ABSTRACT

1. Psychophysiological Response to Stress: A Potential Mediator of Negative Urgency and Alcohol UseErin Walsh, M.S., Karen Derefinko, Ph.D., Richard Milich, Ph.D. & Don Lynam, Ph.D.*Department of Psychology, University of Kentucky *University of Purdue, Department of Psychological Sciences ABSTRACT DISCUSSION METHOD Table 1. Correlations between Negative Urgency, Cardiac PEP, and Alcohol Consumption Patterns. • Findings and Implications. • Negative Urgency was strongly related to periods of alcohol use and heavy alcohol consumption. • Negative Urgency was also positively associated with cardiac PEP at Baseline and Recovery periods. • These results suggest that individuals high in Negative Urgency experience increased sympathetic arousal in resting states and may have difficulty recovering from stressful events. • Contrary to predictions, psychophysiological response to stress did not mediate the relation between Negative Urgency and patterns of alcohol use. Specifically, SNS activity at all time periods (as assessed by cardiac PEP) was unrelated to alcohol use or abuse. • The following explanations are offered for this unexpected finding: • SNS activity may not mediate the relation between Negative Urgency and patterns of alcohol use. • Individuals high in Negative Urgency may experience decreased impulse control in domains other than alcohol use when experiencing strong or “unpleasant” physiological sensations. That is, SNS response to stress may mediate the relation between Negative Urgency and other maladaptive behaviors (e.g., self-injury). • Underage college students, such as those in the present sample, may lack sufficient exposure to the negatively-reinforcing effects in question to acquire strong patterns of maladaptive alcohol use. • The PASAT-C may be an insufficient stressor. As seen in Figure 2, the change in cardiac PEP from Pre-Task Baseline to Stressor is in the opposite- expected direction. This suggests that participants may not have experienced high levels of distress during the task. • Future directions. • Consider the use of alternative laboratory stressors, such as personalized vignettes (Sinha et al., 2004) or aversive pictures (Colder, 2001). • Explore relations between Negative Urgency, alcohol use, and parasympathetic nervous system (PNS) reactivity to stress. • Examine if SNS/PNS-response to stress mediates relations between Negative Urgency and other types of substance abuse or other types of maladaptive behavior. • Participants. • Participants (N=223) were introductory psychology students from the University of Kentucky. • Self-Report Measures. • UPPS Impulsive Behavior Scale (UPPS; Whiteside & Lynam, 2001). The UPPS is a 45-item measure assessing four distinct personality pathways to impulsive behavior: Negative Urgency, (lack of) Premeditation, (lack of) Perseverance, and Sensation-seeking. For the present analyses, only Negative Urgency was used. • Life-History Calendar (LHC; Caspi et al., 1996). The LHC is a data-collection method that asks participants to retrospectively recall life events and behaviors. The LHC uses a grid to document the occurrence of particular events in a participant’s life. • For the present study, we used the LHC to assess alcohol consumption patterns from the age of 13 to the time of testing. Specifically, we examined the total number of periods in which a participant reported any alcohol use or heavy alcohol use (i.e., five or more drinks). • Physiological Measures. • Cardiac Pre-Ejection Period (PEP). PEP is an index of sympathetic cardiac control. Shortened PEP is reflective of greater sympathetic nervous system (SNS) influence. PEP was assessed at three separate time points: • Pre-Task Baseline • Stressor • Post-Task Recovery Period • Laboratory Task. • Paced Auditory Serial Addition Task-Computerized Version (PASAT-C; Lejeuz et al., 2003). The PASAT-C is a computerized arithmetic task known to induce emotional distress. In this task, numbers are sequentially presented on a computer screen. Participants are asked to add each newly presented number to the previously displayed number. The task consists of three levels which progress in difficulty. For the present study, we defined our “Stressor” as a one-minute period when latency between number presentations first decreased. • Procedure. • Participants were enrolled in a larger study examining multiple predictors of substance use. The 2.5 hour protocol entailed administration of various self-report questionnaires, behavioral measures, and a psychophysiological assessment. Purpose. This study investigated the role of stress in the Negative Urgency-alcohol relation. Specifically, psychophysiological response to stress was examined as a potential mediator of Negative Urgency and alcohol consumption patterns. Methods. Participants (N=223) were introductory psychology students. Participants completed self-report measures assessing personality traits related to impulsive behavior, as well as alcohol consumption patterns from the age of 13 to the time of testing. Participants were then exposed to a computerized arithmetic task known to cause emotional distress. Level of sympathetic arousal, as measured by cardiac pre-ejection period (PEP), was assessed at three separate time points: Pre-Task Baseline; Stressor; Post-Task Recovery. Results. Negative Urgency positively correlated with periods of alcohol use and heavy alcohol consumption. Negative Urgency was also significantly related to cardiac PEP at Pre-Task Baseline and Post-Task Recovery periods. Contrary to predictions, cardiac PEP was unrelated to patterns of alcohol use. Due to null findings, the proposed mediation was not tested. Discussion. These findings suggest that individuals high in Negative Urgency experience increased sympathetic arousal in resting states and may have difficulty recovering from stressful events. However, psychophysiological response to stress may not be the mechanism which leads to maladaptive alcohol use in those high in Negative Urgency. Possible explanations are offered for this finding. ** p < .01 * p < .05 Note.NegUrg= Negative Urgency, from UPPS Impulsive Behavior Scale (Whiteside & Lynam, 2001). PEP=Cardiac Pre-Ejection Period. AlcUse=Period of any alcohol use. AlcHeavy= Period of heavy alcohol use, from Life History Calendar (Caspi et al., 1996). Figure 1. Cardiac PEP as a Function of Negative Urgency: Expected Finding INTRODUCTION • Negative Urgency, or the tendency to act rashly under conditions of negative affect, strongly predicts alcohol use, dependence, and addiction-related problems (Whiteside & Lynam, 2003; Verdejo-Garcia et al., 2007; Fischer & Smith, 2008). • Individuals high in Negative Urgency may struggle with executiveprocesses such as risk evaluation and inhibition in the presence of negative affect (Kaiser et al., in prep). • The temporary relief from negative affect when using substances, which increases the likelihood of future use (Fischer & Smith, 2008), may explain the ability of Negative Urgency to predict substance use and dependence. • Although many studies have examined the link between stress and alcohol use, few have explored what role, if any, Negative Urgency plays in this relation. Given that stressful situations often evoke negative emotions and overwhelming physical sensations, this particular facet seems particularly relevant to this area of study. • The purpose of the present study was to investigate the role of stress in the Negative Urgency-alcohol relation. The following predictions were made: • Negative Urgency will positively correlate with alcohol use and abuse. • Negative Urgency will positively correlate with sympathetic nervous system (SNS) activity during a stressful laboratory task. • Psychophysiological response to stress will mediate the relation between Negative Urgency and alcohol consumption patterns. RESULTS Figure 2. Cardiac PEP as a Function of Negative Urgency: Obtained Finding As predicted, Negative Urgency significantly correlated with self-reported periods of alcohol use and heavy alcohol consumption. Negative Urgency also showed strong significant relations with cardiac PEP at Pre-Task Baseline and Post-Task Recovery periods. Contrary to expectations, sympathetic activity (as assessed by cardiac PEP) decreased in response to a stressor. This indicates that the PASAT-C did not evoke a stress response in the present sample. There were no relations between cardiac PEP at any specified time point and patterns of alcohol use. As the observed findings did not meet criteria to test meditational hypotheses, the proposed mediation was not tested. ACKNOWLEDGEMENTS Research supported by: NIDA DA005312 Thanks to Mark Fillmore, Ph.D. for poster sponsorship. Correspondence concerning this poster can be sent to Erin Walsh, University of Kentucky. Email: edubwalsh@gmail.com