Altered balance in the autonomic nervous system in schizophrenic patients

The aim of the present study was to evaluate the autonomic nervous function in schizophrenic patients. Twenty-eight patients (29 +/- 6 years) diagnosed as schizophrenics and in stable medication were included, together with ten schizophrenic patients (25 +/- 5 years) who were unmedicated. Eleven healthy subjects (32 +/- 7 years) served as controls. Immediate heart-rate responses to a single deep inspiration was used as a measure of parasympathetic function. Heart-rate response to standing was used as a measure of sympathetic function. Supine blood pressure, heart-rate and orthostatic changes in blood pressure did not differ between groups. Heart-rate response to standing was greater in both medicated and non-medicated schizophrenics compared to normal subjects (P less than 0.01). Heart-rate response to standing was greater in non-medicated compared to medicated schizophrenics (P less than 0.05). Heart-rate response to inspiration was greater in non-medicated schizophrenics compared to normal subjects (P less than 0.05), whereas no difference was found between medicated and non-medicated schizophrenics. The results show that the balance in the autonomic nervous system is altered in schizophrenic patients with a hyperexcitability in both the sympathetic and the parasympathetic division. Our study has thus indicated a dysfunction in the autonomic nervous system per se and the previous interpretations of attentional orienting responses in schizophrenia is questioned. Medication with neuroleptics seems to partly normalize the autonomic reactivity rather than being the cause of autonomic dysfunction.