Dimensions of impulsivity among heavy drinkers, smokers, and heavy drinking smokers: singular and combined effects.

Alcohol use and cigarette smoking commonly co-occur. The role impulsivity may play as a common underlying mechanism in alcohol use and cigarette smoking is of particular interest due to emerging evidence of it being a critical component across multiple forms of addiction. Impulsivity can be examined through several constructs including, risky decision-making, response inhibition, and delay reward discounting. Impulsivity and each of these specific constructs play significant roles in the initiation of drug use, continued use despite negative consequences, and potential to relapse. This study used three behavioral tasks to measure risky decision-making (balloon analog risk test; BART), response inhibition (stop signal task; SST), and delay reward discounting (delay discounting task; DDT). This study advances research on impulsivity and substance use by parsing out the various components of impulsivity and examining them across three groups, heavy drinkers only (HD) (N=107), smokers only (S) (N=67), and heavy drinking smokers (HDS) (N=213). Participants completed questionnaires, interviews, and neurocognitive tasks including the SST, BART, and DDT. Analyses supported an additive effect of alcohol and nicotine use in delay reward discounting. Heavy drinking smokers displayed steeper delay discounting of small rewards than did smokers only (p<.05) and heavy drinkers only (p<.05). This additive effect of smoking and drinking was not observed for risky decision-making and response inhibition, suggesting specificity of the effects for delay reward discounting. These findings indicate that those who both drink heavily and smoke cigarettes daily have increased delay reward discounting, than those in the S and HD groups. Future studies should examine these constructs longitudinally, as well as incorporate genetic and/or a neuroimaging component to these group comparisons in order to ascertain the biological bases of these behavioral findings.