Abstract
Suppressed heart rate variability (HRV) has been found in a number of psychiatric conditions, including schizophrenia and autism. HRV is a potential biomarker of altered autonomic functioning that can predict future physiological and cognitive health. Understanding the HRV profiles that are unique to each condition will assist in generating predictive models of health. In the current study, we directly compared 12 adults with schizophrenia, 25 adults with autism, and 27 neurotypical controls on their HRV profiles. HRV was measured using an electrocardiogram (ECG) channel as part of a larger electroencephalography (EEG) study. All participants also completed the UCLA Loneliness Questionnaire as a measure of social stress. We found that the adults with schizophrenia exhibited reduced variability in R-R peaks and lower low frequency power in the ECG trace compared to controls. The HRV in adults with autism was slightly suppressed compared to controls but not significantly so. Interestingly, the autism group reported feeling lonelier than the schizophrenia group, and HRV did not correlate with feelings of loneliness for any of the three groups. However, suppressed HRV was related to worse performance on neuropsychological tests of cognition in the schizophrenia group. Together, this suggests that autonomic functioning is more abnormal in schizophrenia than in autism and could be reflecting health factors that are unique to schizophrenia.
Highlights
Schizophrenia and autism share many neuropsychological, symptom, and biological characteristics [1, 2], suggesting similar underlying physiological mechanisms may be driving or contributing to the conditions [3,4,5]
Heart rate (HR) was significantly different between groups [F(2, 49) = 3.94, p = 0.026], due to nominally elevated heart rate (HR) in the schizophrenia group compared to controls, but this was not significant in post-hoc comparisons
HR was negatively correlated with standard deviation in R-R peaks (SDNN) [rs[50] = −0.93, p < 0.001], and this was consistent for all three groups
Summary
Schizophrenia and autism share many neuropsychological, symptom, and biological characteristics [1, 2], suggesting similar underlying physiological mechanisms may be driving or contributing to the conditions [3,4,5]. Altered autonomic functioning is common across both autism and schizophrenia and is related to several comorbid conditions including cardiac, gastrointestinal, and autoimmune disorders [6,7,8]. A common measure of autonomic functioning that has been shown to be abnormal in both schizophrenia and autism is reduced heart rate variability (HRV) [9,10,11]. HRV refers to the variability in number of heartbeats within a given period. This variability is commonly interpreted to reflect autonomic functioning, with low variability reflecting a suppressed autonomic system [12, 13].
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