• Eight patients developed a syndrome marked by features of catatonia (including posturing, waxy flexibility, withdrawal and regression) and parkinsonism (including bradykinesia and rigidity) while receiving high-potency neuroleptic drugs. The syndrome had a gradual onset, responded slowly to withdrawal of the neuroleptic or use of an anticholinergic agent, but seemed to respond more rapidly to amantadine. The syndrome may easily be confused with a worsening of schizophrenic symptoms.
Gelenberg AJ, Mandel MR. Catatonic Reactions to High-Potency Neuroleptic Drugs. Arch Gen Psychiatry. 1977;34(8):947-950. doi:10.1001/archpsyc.1977.01770200085010