Aberrant Salience and Control as Risk Factors for Addiction

Salience is central to a prominent theory of addiction known as incentive sensitization theory (IST; e.g., Robinson & Berridge, 1993). Briefly, IST posits that, through use of addictive drugs, including alcohol, people learn to pair the rewarding feelings they experience (relaxation, stimulation) with various cues present during drug use. Eventually, repeated pairing of drug-related cues with reward leads those cues to take on the rewarding properties of the drug itself. That is, the cues become infused with incentive salience, triggering craving, approach and consummatory behavior.

Research has shown critical individual differences in vulnerability to attributing incentive salience to drug cues, and that vulnerable individuals are at much higher risk for addiction. Moreover, combining incentive sensitization with poor cognitive control (e.g., during a drinking episode) makes for a “potentially disastrous combination” (Robinson & Berridge, 2003, p. 44). To date, IST has been tested primarily in preclinical animal models. Part of our work aims to translate IST to a human model.

In a number of studies over the past decade, we have discovered that a low sensitivity to the effects of alcohol (i.e., needing more drinks to feel alcohol’s effects), known to be a potent risk factor for alcoholism, is associated with heightened incentive salience for alcohol cues. Compared with their higher-sensitivity (HS) peers, among low-sensitivity (LS) drinkers alcohol-related cues (a) elicit much larger neurophysiological responses (Bartholow et al., 2007, 2010; Fleming & Bartholow, in prep.); (b) capture selective attention (Shin et al., 2010); (c) trigger approach-motivated behavior (Fleming & Bartholow, 2014); (d) produce response conflict when relevant behaviors must be inhibited or overridden by alternative responses (Bailey & Bartholow, 2016; Fleming & Bartholow, 2014), and (e) elicit greater feelings of craving (Fleming & Bartholow, in prep.; Piasecki et al., 2017; Trela et al., in press). These findings suggest that LS could be a human phenotype related to sign-tracking, a conditioned response reflecting susceptibility to incentive sensitization and addiction (Robinson et al., 2014).

Recently, our lab has conducted two major projects designed to examine how the incentive salience of alcohol-related cues is associated with underage drinking. One such project, funded by the National Institute on Alcohol Abuse and Alcoholism (NIAAA; R01-AA020970), examined the extent to which pairing beer brands with major U.S. universities enhances the incentive salience of those brands for underage students. Major brewers routinely associate their brands with U.S. universities through direct marketing and by advertising during university-related programming (e.g., college sports). We tested whether affiliating a beer brand with students’ university increases the incentive salience of the brand, and whether individual differences in the magnitude of this effect predict changes in underage students’ alcohol use. We found (a) that P3 amplitude elicited by a beer brand increased when that brand was affiliated with students’ university, either in a contrived laboratory task or by ads presented during university-related sports broadcasts; (b) that stronger personal identification with the university increased this effect; and (c) that variability in this effect predicted changes in alcohol use over one month, controlling for baseline levels of use (Bartholow et al., 2018).

A current project, also funded by the NIAAA (R01-AA025451), aims to connect multiple laboratory-based measures of the incentive salience of alcohol-related cues to underage drinkers’ reports of craving, alcohol use, and alcohol-related consequences as they occur in their natural environments. This project will help us to better understand the extent to which changes in drinking lead to changes in alcohol sensitivity and to corresponding changes in the incentive salience of alcohol-related cues.