Withdrawal syndromes associated with antipsychotic drugs.

Withdrawal symptoms frequently follow abrupt discontinuation of antipsychotic compounds. In addition to other somatic symptoms, withdrawal-emergent dyskinesias may be observed. "Covert dyskinesia" refers to a masked form of tardive dyskinesia that becomes clinically detectable only after antipsychotic drugs are withdrawn or their dosage is reduced. Withdrawal dyskinesia appears under similar circumstances but disappears spontaneously in 6 to 12 weeks. Cholinergic overactivity and changes in dopamine-acetylcholine balance in the basal ganglia may underlie these withdrawal syndromes. The principal value of the concept of covert dyskinesia is in the secondary and tertiary prevention of tardive dyskinesia through early discovery and treatment.