Variations of Aripiprazole-Induced Dyskinesia Existing with Concurrent Use of Amantadine and an Anticholinergic Agent in an Elderly Patient☆

Summary Elderly patients are vulnerable to the adverse neurological effects of antipsychotics, particularly Parkinsonian symptoms and tardive dyskinesia. This vulnerability in the elderly becomes complex and unpredictable when aripiprazole is prescribed to replace other second-generation or first-generation antipsychotics. This report describes a 69-year-old female schizophrenic patient, who received aripiprazole after using a few antipsychotics, including the first- and second-generation ones. The tardive dyskinesia developed 6 weeks after switching to aripiprazole but subsided 4 weeks later when stopping the concurrent amantadine and decreasing the dosage of trihexyphenidyl. However, Parkinsonian symptoms developed insidiously thereafter, which remitted after the dosage of trihexyphenidyl was increased again. The possible mechanisms of the alternated adverse neurological events after a switch to aripiprazole in the chronic elderly psychosis are discussed.