Sex Differences in Motivation to Self-Administer Alcohol After 2 Weeks of Abstinence in Young-Adult Heavy Drinkers.

ABSTRACT

BACKGROUND: Studies in animal models document that forced abstinence from usual consumption of alcohol changes subsequent seeking and consumption, with increases or decreases depending on the species, duration of abstinence, number of deprivations, and sex. Human laboratory-based alcohol deprivation studies are rare. METHODS: We conducted a 2-session, within-participant, randomized-order comparison of intravenous, progressive ratio, alcohol self-administration during 2.5 hours of progressive work for alcohol and/or vehicle; once while the participants pursued their usual drinking habits and once after 2 weeks of closely monitored, voluntary outpatient abstinence from alcohol. The schedule of work for rewards and the incremental increases in breath alcohol concentration following completion of an alcohol work-set were identical across participants. Fifty young-adult (27 men), heavy-drinking participants completed both sessions. Our primary hypothesis was that motivation to work for alcohol after 2 weeks of abstinence would be greater in participants with a weekly binge pattern of drinking, compared to those who regularly drink heavily, and we intended to explore associations with biological family history of alcoholism and sex. RESULTS: We detected no change in work for alcohol associated with recent drinking history. However, females, on average, increased their work for alcohol upon resumption after 2 weeks of abstinence (mean ± SEM = +16.3 ± 9.6%), while males decreased that work (-24.8 ± 13.8%). The sex difference was substantial and significant (p < 0.03), with a medium effect size (Cohen's d = 0.63). CONCLUSIONS: We believe a more comprehensive study of mechanisms underlying the sex differences in the human postabstinence response is warranted.