Disabling repetitive behaviors in Parkinson's disease.

We report on 6 patients with Parkinson's disease who developed severe repetitive behavior, 2 with pathological gambling and 4 with cleaning, rearranging, and ordering rituals. The onset of repetitive behaviors was not associated with changes in antiparkinsonian medications, the behavior did not improve after reductions in dopaminergic therapy, and thus they seem to be part of the underlying illness. The disabling cleaning/rearranging/ordering behaviors had associated features of hypomania, occurred exclusively during motor on periods, and often occurred nocturnally. The repetitive behavior responded poorly to serotonin reuptake inhibitors. Certain atypical antipsychotics may be of benefit.