Chlorpromazine effects on stereotypic and conditioned behaviour of severely retarded patients--a pilot study.

An attempt was made to test the hypothesis that anti-psychotic medication may induce adaptive changes by suppressing stereotypic behaviour. Six profoundly retarded residents were selected for the presence or absence of stereotypic behaviour and tested in a placebo controlled, cross-over study. Chlorpromazine caused noticable drowsiness in all subjects over the 2-week drug period. Body rocking was significantly suppressed in the wards, but other clinical behaviours were not influenced by the drug. Performance on an operant conditioning task was significantly impaired in most subjects. Body rocking, which was also assessed during operant responding, was unrelated to presence or absence of clinical stereotypy, observed on the wards. The results were discussed in terms of chlorpromazine's clinical effects and improved ways of assessing the hypothesis that anti-psychotic drugs may enhance adaptive behaviour in some retarded individuals.