Background: Characteristic behaviors of some alcohol-dependent individuals, e.g., binge drinking, comorbid psychopathology, and some types of alcohol-related problems, have been linked to abnormalities in serotonergic neurotransmission. However, studies that have evaluated serotonergic pharmacotherapy for reducing drinking have yielded conflicting results. One explanation for these findings is a general failure to distinguish alcohol subgroups that may be differentiated on the basis of serotonergic abnormalities. However, in 1996, Kranzler and colleagues reported that Type B alcoholics, who are characterized by high levels of premorbid vulnerability, alcohol dependence severity, and comorbid psychopathology, showed less favorable drinking outcomes in response to treatment with fluoxetine, a serotonin reuptake inhibitor, than with placebo. This medication effect was not seen in Type A alcoholics, i.e., those with lower risk/severity of alcoholism and psychopathology. The aim of the present study was to explore the validity of differential responding by alcohol-dependent subtypes using the serotonin reuptake inhibitor, sertraline.
Methods: A k-means clustering procedure was applied to a sample of alcohol-dependent subjects enrolled in a 14-week, placebo-controlled trial of 200 mg/day of sertraline, classifying them into lower-risk/severity (Type A: n = 55) and higher-risk/severity (Type B: n = 45) subgroups.
Results: A significant interaction between alcoholic subtype and medication condition was found, confirming the findings of Kranzler and colleagues that alcoholic subtypes responded differentially to serotonergic medication. Somewhat at variance with their results, however, the present study showed that the lower risk/severity (Type A) subjects had more favorable outcomes when treated with sertraline compared to placebo.
Conclusions: Alcoholic subtypes differentially responded to sertraline when used as a treatment to reduce alcohol drinking, with one subtype having more favorable outcomes. Subtyping alcoholics may help to resolve conflicting findings in the literature on serotonergic treatment of alcohol dependence.