EFFECTS OF HALOPERIDOL AND AMISULPRIDE ON MOTOR AND COGNITIVE SKILL LEARNING IN HEALTHY-VOLUNTEERS

The effects of a typical neuroleptic, haloperidol (1 and 2 mg orally), of an atypical neuroleptic, amisulpride (50 and 100 mg) and of a plac ebo on motor and cognitive skill learning were assessed in 60 healthy volunteers using repeated testing on the Tower of Toronto puzzle. Subj ects were asked to solve three blocks of eight trials and, at distance from drug administration, a fourth block. The puzzle was connected to a computer in order to obtain a precise timing of individual moves. T wo components of cognitive skill learning were assessed, the ability t o learn to solve the puzzle and the acquisition of a problem-solving r outine. Subjective feelings of effort and automatisation of the task w ere assessed using a questionnaire. Like placebo-treated subjects? neu roleptic-treated subjects were able to acquire a motor skill, to learn to solve the puzzle and to acquire a routine. However, haloperidol 2 mg-treated subjects needed significantly more moves to solve the puzzl e in blocks 3 and 4, some of them having routinised a non-optimal solu tion. A significant cognitive slowing was observed in the haloperidol 1 mg group in block 4. The performance pattern and verbal reports sugg ested that haloperidol impaired the higher cognitive functions such as the ability to shift from one strategy to another and/or to assess on e's performance accurately, possibly leading to the development of com pensatory strategies. The only deleterious amisulpride effect was a co gnitive slowing in block 4, which was observed in the lower dose group .