Age-related variations in heart rate variability profiles among patients with schizophrenia and major depressive disorder.

Patients with psychiatric disorders exhibit general autonomic dysregulation and elevated cardiovascular risks, which could be indexed by heart rate variability (HRV). However, HRV is susceptible to age and other patient-specific factors. This study aimed to investigate the HRV profile and age-related variations, as well as the potential influence of sex, BMI, and HR on HRV in psychiatric populations. There were 571 consecutive patients diagnosed with schizophrenia (SZ) (N = 282) or major depressive disorder (MDD) (N = 289) recruited and classified as adolescent (11-21 years) and adult (> 21 years) groups. HRV indices were measured with 3-minute resting ECG recordings. Compared to adolescent subjects, all time-domain and nonlinear HRV indices were notably reduced in adults, while frequency-domain HRV was comparable. Between SZ and MDD groups, only HTI differed significantly. Age and psychiatric disorders exhibited complex interaction effects on HRV. Stratified by age stage, MDD patients exhibited slightly higher HRV in adolescence but slightly lower HRV in adulthood. In logistic regression analysis, HTI and SD2 were significantly distinctive between adolescents and adults in MDD group, while pNN50 was distinctive in SZ group. Moreover, female subjects demonstrated lower time-domain HRV, LF/HF and SD2 than males. HR exhibited inverse relationship with three domain HRV. No significant effect of BMI was observed. In psychiatric populations, compared to adolescents, adults decreased in time-domain and nonlinear HRV, but not in frequency-domain HRV. Age and psychotic disorders exhibited complex interaction effects on HRV. Sex and HR also emerged as important influencing factors of HRV.