Objective: The objective of the study was to determine whether patients with schizophrenia and their unaffected first-degree relatives have abnormal autonomic nervous system (ANS) responses to social cognition tasks.
Background: Social cognition impairments are significant in schizophrenia. ANS activity has been shown to be abnormal in schizophrenia patients, and some of the abnormalities seem to be shared by patients' unaffected relatives.
Method: Heart rate variability (HRV) was measured at rest and during social cognition tasks, in patients with schizophrenia, their nonpsychotic first-degree relatives, and matched healthy controls (n=19 in each group).
Results: Social cognition tasks induced a shortening of the RR interval in unaffected relatives, but not in patients. Social cognition tasks generated decreases in high-frequency (indicating cardiac vagal activity) and low-frequency (reflecting predominantly sympathetic activity) HRV in patients. In relatives, the decrease occurred in the high-frequency component only. Low-frequency HRV was higher in patients during a theory of mind task than a control task. These changes were not observed in the controls.
Conclusions: Social cognitive tasks induce a pattern of peripheral autonomic activity different from that seen in generic arousal responses, and this pattern is abnormal in schizophrenia patients. Autonomic abnormalities in unaffected first-degree relatives seem restricted to the parasympathetic division of the ANS.