Increased hexosaminidase activity in antipsychotic-induced extrapyramidal side effects: possible association with higher occurrence in bipolar disorder patients.

Dystonic movements and Parkinsonism are frequently seen in gangliosidoses and these conditions have been reported to modify dopaminergic plasticity. We investigated whether the activity of hexosaminidase, a type-two ganglioside (GM2) degrading enzyme, correlates with drug-induced extrapyramidal system (EPS) side effects in psychiatric patients. We compared hexosaminidase activity in the lymphocytes of 29 EPS-positive patients, 13 EPS-negative patients, and 30 healthy volunteers. The activities of A and B isoforms of hexosaminidase were higher in EPS-positive patients than EPS-negative patients and healthy controls. Multivariate analysis suggested an interaction with increased B isoform activity and EPS side effects in female bipolar disorder patients. Higher levels of hexosaminidase enzyme activity may explain the frequent occurrence of antipsychotic-induced extrapyramidal side effects in mood disorder patients.