  Heart rate (HR) and its variability (HRV) has been proposed as a marker for
depressive symptoms and other aspects of mental health. However, the real
correlation between them is presently uncertain, as previous studies have
generally been conducted on the basis of small samples. In a sample of 113
adult male prisoners, we analyzed correlations between five measures of HR/HRV
and five psychological measures of mental health aspects (depression, state and
trait anxiety, and social relationships). We used Nadaraya-Watson
non-parametric regression in both directions and age-stratified Spearman
correlation to detect possible relations. Despite strong correlations among
HR/HRV measures and among psychological measures, correlations between HR/HRV
and psychological measures were low and non-significant for the overall sample.
However, we found an age dependency, suggesting some correlations in younger
people (HR with STAI-State, r = 0.39; with HADS-Anxiety, r = 0.52; both p <
.005). Overall, the general utility of HR/HRV as a marker for mental health
across populations remains unclear. Future research should address age and
other potential confounders more consistently.
