Asymmetrical hand force persistence and neuroleptic treatment in schizophrenia

The recent development of an isometric instrument for the precise quantific ation of hand force persistence has created a novel opportunity for the eva luation of potential motor asymmetries in schizophrenia and their response to treatment. A study of asymmetries in the unmedicated state may provide i nsight into the pathogenesis of schizophrenia, whereas alterations of asymm etries in response to antipsychotic medication could assist the delineation of a cerebral mechanism for the effects of pharmacotherapy. The hand force persistence of 21 unmedicated patients with schizophrenia was compared to 21 age, gender, and handedness matched normal controls. The effect of neuro leptic treatment on hand force persistence was then evaluated on a subset o f 10 patients after at least 30 days of treatment. The anticipated asymmetr y was evident in the unmedicated sample that showed impaired right hand for ce persistence compared to the normal control sample. The prospective compa rison showed an alleviation of the asymmetry resulting from an improvement of right hand force persistence with treatment. In addition to providing fu rther support to a primary left hemisphere cerebral involvement in schizoph renia, the present results suggest that prior investigations of motor asymm etry may have been compromised by the study of medicated patients. The appa rently paradoxical improvement of motor skill may relate to the substantial number of patients treated with 2nd generation neuroleptic medications whi ch may implicate an improvement in left hemisphere physiology in the cognit ive advantages of the novel treatments.