Prediction of serotonergic treatment efficacy using age of onset and Type A/B typologies of alcoholism

Previously, we reported that ondansetron was efficacious at treating early-onset (< or =25-years old) but not late-onset (> or =26-years old) alcoholics in a double-blind, randomized, placebo-controlled clinical trial (n = 321 enrolled patients, 271 of them randomized). Randomized participants underwent 11 weeks of treatment with ondansetron (1, 4, or 16 microg/kg twice daily; n = 67, 77, and 71, respectively) or identical placebo (n = 56), plus weekly standardized group cognitive behavioral therapy.

For this study, we reanalyzed the original sample to determine whether the Type A/B typological classification predicts ondansetron treatment response. In this comparative analysis, k-means clustering was applied to 19 baseline measures of drinking behavior, psychopathology, and social functioning, similar to those used by Babor in the original typological derivation. A 2-factor solution described robustly 2 groups phenomenologically consistent with Type A/B classification. Subjects were subdivided into early- and late-onset alcoholics.

Seventy-two percent of Type B subjects had early-onset alcoholism (EOA); 67% of Type A subjects had late-onset alcoholism (LOA). The A/B typology better discriminated 2 clusters based upon baseline severity of alcoholism. There was a significant effect (p < 0.05) for Type B alcoholics to respond to ondansetron (4 microg/kg); however, Type A alcoholics receiving ondansetron showed no beneficial effect. Early-onset vs. late-onset classification predicted ondansetron response substantially better than Type A/B classification, which did not add to the prediction of treatment outcome. Further analyses showed that ondansetron was effective in the 33% of Type A alcoholics with EOA but ineffective in the 28% of Type B alcoholics with LOA.

Type A/B classification best discriminates alcoholic subtypes based upon baseline severity. Early- vs. late-onset classification is, however, a better predictor of response to ondansetron treatment because it might be more closely related to fundamental neurobiological processes associated with the underlying pathophysiology of alcoholism.