Neuromuscular and psychomotor abnormalities in patients with schizophreniaand their first-degree relatives

In previous studies of schizophrenic patients, neuromuscular (histopatholog ical and electrophysiological) and psychomotor (finger tapping) abnormaliti es were found. The present study was designed to investigate relationships between these abnormalities and a family history of psychosis in 14 schizop renic patients and 25 unaffected first-degree relatives compared to 14 heal thy controls. Muscle biopsies were performed in either m. tibialis anterior or m. lateralis. Macro EMG recordings were made from m. tibialis anterior. A finger tapping test was used to investigate psychomotor performance. Neu romuscular abnormalities (muscle biopsies and/or macro EMG) and/or aberrant psychomotor performance (finger tapping test) were found in 13 (93%) patie nts, 14 (56%) first-degree relatives and in three (21%) controls. A statist ically significant relationship for the psychomotor, but not neuromuscular changes to a family history of psychosis was found using a logistic regress ion method. The percentage of patients, relatives and healthy controls exhi biting were 36/40/7% in the muscle biopsy, 50/20/0% in the macro EMG, and 7 1/82/14% in the finger tapping investigations. A higher frequency of neurom uscular and psychomotor abnormalities was found in patients with schizophre nia and their first-degree relatives compared to healthy controls. The rela tionship between psychomotor findings and a family history of psychosis ind icate that central aspects of motor aberrations are associated with a hered itary disposition of psychosis. The neuromuscular as well as psychomotor ch anges indicate that schizophrenia may be a systemic disease involving the c entral nervious system as well as peripheral organs. An altered cell membra ne is suggested to be an underlying factor based on the type of neuromuscul ar findings. (C) 2000 Elsevier Science Ltd. All rights reserved.