Finally, preliminary studies have examined whether individual SUD diagnoses reflect single or multiple dimensions of genetic risk. Studies of a wide range of alcohol-related responses in rodents indicate that they often reflect independent genetic influences. A recent large-scale twin study found three distinct dimensions of genetic risk underlying the criteria set forth in the Diagnostic and Statistical Manual of Mental Disorders IV (ref. 1) (DSM-IV) for alcohol dependence. These reflect (i) liability to heavy drinking and tolerance, (ii) self-recognition of alcohol-related problems, loss of control, desire to quit, preoccupation and activities given up, and (iii) withdrawal and continued use despite problems. These three dimensions of genetic risk are only modestly correlated in alcohol-dependent subjects and differentially predict risk for other psychiatric and substance use disorders and personality traits.
