Physiological and psychological effects of methadone in man.

Methadone hydrochloride-maintenance outpatients were compared to abstinent exaddicts on physiological and psychological measures, and to normal subjects on physiological measures. The battery of psychological tests measure cognitive abilities and mental state. Methadone depressed respiration rate below other groups; abstinent subjects had higher heart rates than methadone or control subjects. No other physiological differences appeared. Electroencephalographic spectral analysis disclosed that the location of the alpha peak was at the lowest frequency in the methadone group, next lowest being the abstinent group. Discriminant functions based on a weighted combination of variables (frequencies) successfully distinguished the EEGs of the three groups. Both discriminant analysis and multiple regression analysis indicated that EEG changes were dose-dependent. Methadone subjects performed significantly poorer on several tests of learning and immediate recall compared to absitinent subjects.