The MacAndrew Alcoholism Scale in epilepsy: a high false positive error rate.

A substantial proportion of patients with epilepsy seen in a large medical center were found to be incorrectly classified as possible substance abusers by the MacAndrew Alcoholism Scale (MAC) of the MMPI. Demographic variables, IQs, and MAC scale raw scores were compiled for a sample of 29 male and 33 female seizure patients. No significant or meaningful differences were found between the sexes; therefore, the sample was treated as a single group. False positive error rates on the MAC scale were 48.39% when MacAndrew's originally proposed raw score cut-off of 24 was used; 30.65% with a cut-off of 26; 20.97% with a cut-off of 28; and 9.68% with a cut-off of 30. A similarity of experiential and behavioral characteristics between seizure patients and substance abusers is suggested as a possible reason for the findings. A greater awareness of this high false positive rate for epilepsy patients is needed to differentiate drug-/alcohol-induced from non-induced seizures and to prevent inappropriate labeling of seizure patients by the various professional groups who utilize the MMPI. Suggestions are made for future research.