Four addictions: the MMPI and discriminant function analysis

Over the past twenty years many MMPI studies of substance abuse have investigated the complex relationship between personality profile and drug of choice. This work has repeatedly established that alcoholics, heroin, cocaine and polydrug addicts share 4-2/2-4 (Psychopathy and Depression) or 4-8/8-4 (Psychopathy and Thought Disorder) MMPI profiles, but that the substance abuse populations differ in the plane of severity in that general profile. The alcoholics occupy the least disturbed sector, the polydrug abusers the most disturbed level and the heroin and cocaine addicts positions of moderate disturbance. The vast majority of studies, however, cite only group means to buttress their conclusions. Our work probed more deeply into the data using Discriminant Function Analysis. With this methodology we discovered important differences between the groups, previously hidden, which may carry differential treatment implications.