Spit for Science and the Limits of Applied Psychiatric Genetics

The research program Spit For Science was launched at Virginia Commonwealth University (VCU) in 2011. Since then, more than 10,000 freshmen have been enrolled in the program, filling out extensive questionnaires about their drinking, general substance use, and related behaviors, and also contributing saliva for genotyping. The goals of the program, as initially stated by the investigators, were to find the genes underlying the heritability of alcohol use and related behaviors, and in addition to put genetic knowledge to work in ways that might aid university administrators and mental health professionals in the prevention and treatment of substance abuse. We review every empirical paper involving genetic data that has emerged from the program, and reach a surprising conclusion: the study has never identified a single genetic effect of more than trivial magnitude. Although the quantitative results of the studies were reported transparently, the theoretical ramifications of the negligible results have never been acknowledged. To the contrary, most of the papers ignore the tiny effects, reaching optimistic conclusions about the prospects for future genetic explanations of alcohol use. We explore the implications of these results for the broader prospects of applied psychiatric genetics.