Prolonged Reaction to Mental Arithmetic Stress in First-Degree Relatives of Schizophrenia Patients

Abstract

Objective: Several studies have reported abnormal heart rate variability (HRV) in schizophrenia patients, suggesting a pathophysiological link between central autonomic dysfunction and symptoms of schizophrenia and that these could be heritable. This study aimed at evaluating cardiac autonomic response to mental arithmetic stress in first-degree relatives of schizophrenia patients (FDRS) employing HRV analysis. Methods: HRV measures were computed for 25 healthy FDRS and 25 age- and gender-matched controls during rest, mental arithmetic stress task and recovery period. Subtracting serial sevens from 700 for five minutes formed the stress task. Recovery period lasted five minutes starting from the termination of the stress task. Results: Both groups showed similar alterations during the stress task. After stress termination, recovery to the basal values was observed in controls but not in patients' relatives, maintaining a pattern similar to that during the stress task. Conclusions: Poor recovery from cardiac autonomic functions (CAF) alterations induced by arithmetic stress may be a heritable trait marker of schizophrenia. Our report supports endophenotypic potential of HRV in schizophrenia research.