Individual Differences in Alcohol Sensitivity
There are wide individual differences in responses to drinking alcohol. Recent estimates claim that subjective effects (how people feel when they drink) vary from 200%-300% in the adult population, and ethanol metabolism (how quickly alcohol is absorbed into the bloodstream and metabolized by the liver) varies by approximately 200%. Unfortunately, alcohol researchers know very little about why such drastic differences occur between individuals and how individual differences in alcohol sensitivity (AS) might link drinking behavior with problematic alcohol-related outcomes. Pilot research conducted by my colleagues and me over the past 5 years suggests that individual differences in AS are related to very basic differences in cognitive processing in a variety of contexts (e.g., Bartholow, Pearson, Sher, Wieman, Fabiani, & Gratton, 2003). Specifically, individuals low in AS (i.e., individuals requiring more drinks to feel intoxicated) show significant deficits in a range of executive cognitive functions, including working memory and categorization efficiency. However, other research indicates that low AS is associated with particularly strong engagement of cognitive-motivational processes in the presence of alcohol cues. Thus, it is not simply the case that low AS results in (or from) a generalized impairment of cognitive-motivational systems.
For several years my colleagues and I have been developing a self-report measure of AS. This research was motivated by our dissatisfaction with a number of existing measures in terms of their lack of specificity and their reliance on participants’ recall of change in sensitivity levels over a period of years. Our current measure consists of 16 items that collectively measure individual differences in both the number of alcohol-related effects people have experienced and the dose of alcohol required to experience those effects.
Recently, we have conducted a series of experiments designed to test how individual differences in AS relate to neural reactivity to alcohol-related cues. The P300 component of the ERP is known to increase as a function of the motivational relevance or emotional salience of a stimulus (e.g., Ito, Larsen, Smith, & Cacioppo, 1998; Schupp et al., 2000). Some theorists have argued that images that arouse emotional responses elicit larger P300 because they activate basic motivational systems (e.g., to approach or avoid). Our interest was in whether the P300 elicited by alcohol-related cues would differ as a function of AS level. Consistent with the idea that low AS is a risk factor for alcohol abuse and dependence (e.g., Schuckit, 1994; Schuckit et al., 2004), our data indicated that alcohol cues elicited enhanced P300 amplitude among low AS relative to high AS individuals. Moreover, this difference held after controlling for recent alcohol use and current indicators of alcohol dependence (Bartholow, Henry, & Lust, under review).