Cortical laterality and asymmetry of the Hoffmann reflex in psychiatric patients

Thirty-six hospitalized patients with schizophrenia or schizo-affective disorder who were judged unresponsive to conventional treatment were tested 5 days after last receiving medication and retested 4 weeks after treatment with thiothixene, loxapine, or molindone. Cortical laterality for linguistic and motor functions was measured by visual half-field (VHF) recognition of words, dichotic listening (DL), the Crawford Small Parts (CSP) performance test, and finger-tapping (FT) dexterity. The recovery curve of the Hoffmann reflex was measured in both legs and lateral asymmetries of the recovery curve were calculated as lateralization coefficients. Cortical laterality measurements were also performed in 36 control subjects. Cortical laterality measures of patients were not significantly different from those of control subjects and were not related to measures of clinical symptomatology. The height of the H-reflex recovery curve (mean of both legs) was not related to clinical symptomatology. Recovery curve height of the right leg only was significantly correlated with the withdrawal-retardation (R) subscale of the Brief Psychiatric Rating Scale (BPRS). Recovery curve height was significantly correlated with number of schizophrenic symptoms recorded for diagnosis based on the Research Diagnostic Criteria (RDC). Recovery curve height (mean of both legs) in medicated patients was significantly correlated with right sided preference as measured by both VHF and DL. In unmedicated patients, lateralization of the recovery curve was correlated with clinical symptomatology, such that relative elevations of the right leg were associated with higher scores of the R subscale of the BPRS, while relative elevations of the left leg were associated with higher scores of the anxious-depression (D) subscale of the BPRS. Left hemispheric or subcortical dysfunction, manifested by recovery curve elevation of the right leg, was related to schizophrenic symptomatology (R subscale). Right hemispheric or subcortical dysfunction, manifested by relative recovery curve elevation in the left leg, was related to depression symptomatology (D subscale). These findings are compatible with asymmetries of subcortical amine function in schizophrenia and schizo-affective disorder.