LAUSR

BACKGROUND High alcohol consumption and alcohol dependence are only partly genetically correlated and they differ considerably in their correlations with other traits. The existence of genetic correlation among alcohol dependence and psychiatric disorders may be attributed to the presence of a general psychopathology factor, the p factor. This study investigates the relationship of polygenic risk to general psychopathology and to high alcohol consumption on alcohol dependence. METHODS Participants were 524 alcohol-dependent patients and 729 controls. Polygenic risk scores (PRS) were computed for alcohol consumption (drinks per week) and nine psychiatric disorders. Principal component analysis (PCA) applied to the psychiatric PRS was used to calculate the first principal component as a proxy of the polygenic p factor. RESULTS Both the polygenic p factor and the drinks per week PRS were associated with alcohol dependence in our sample. Both variables are only weakly correlated, contributing additively to the risk for alcohol dependence. Sensitivity analyses showed that the polygenic p factor was also associated with alcohol dependence in the subset of patients without any psychiatric or substance use comorbidity. CONCLUSIONS Polygenic risk for alcohol dependence can be split at least into two components, involved in general psychopathology and high alcohol consumption. The first component of PCA based on PRS for different psychiatric disorders allows estimation of the contribution of the polygenic p factor to alcohol dependence. The pleiotropic effects of genetic variants across psychiatric disorders are mainly manifested as alcohol dependence in some patients.