Can we subtype alcoholism? A latent class analysis of data from relatives of alcoholics in a multicenter family study of alcoholism.

We attempt to identify distinctive subtypes of alcoholics using latent class analysis with data from 2551 relatives of alcoholic probands, all participants in the Collaborative Study of the Genetics of Alcoholism. Latent class analysis is a multivariate technique using cross-classified data to identify unobserved ("latent") classes that explain the relationships among observed variables. Data on 37 life-time symptoms of alcohol dependence from 1360 female and 1191 male relatives were analyzed, with a 4 class solution selected as the best fitting among the 2 through 6 class solutions that were examined. We observed the following classes: class 1, nonproblem drinkers (39.6% male, 50% female); class 2, mild alcoholics (persistent desire to stop, tolerance, and blackouts) (31.8% male, 28.7% female); class 3, moderate alcoholics (social, health, and emotional problems) (18.9% male, 14.6% female); and class 4, severely affected alcoholics (withdrawal, inability to stop drinking, craving, health, and emotional problems) (9.7% male, 6.7% female). There was little evidence for the construct of alcohol abuse; endorsement probabilities for abuse symptoms (e.g., arrest and DWIs) were very low for all classes, whereas hazardous use was common among men in class 1. In addition to those in class 3 and class 4, a majority of men in class 2 qualified for DSM-III-R alcohol dependence, suggesting a biomodal distribution of drinkers and alcoholics, with little nondependent problem drinking among men in this high-risk sample. We conclude that, in this sample, alcoholism is not differentiated by symptom profiles but rather lies on a continuum of severity, with the possible exception of withdrawal, which characterized only class 4 individuals.