Vagally-mediated heart rate variability and depression in children and adolescents - A meta-analytic update.

Background: Depression is one of the most common mental disorders and a leading cause of disability worldwide. In adults, depression is characterized by decreased vagal activity (vagally-mediated heart rate variability; vmHRV), while vmHRV is inversely correlated with depressive symptoms. In children/adolescents, a 2016 synthesis (4 studies, 259 individuals) found similarly decreased vmHRV in clinical depression, but no significant association between depressive symptoms and vmHRV (6 studies, 2625 individuals). Given the small number of studies previously considered for synthesis and the rapidly growing evidence base in this area, a meta-analytic update was warranted.

Method: A previous review was updated by a systematic literature search to identify studies that (a) compared vmHRV in clinically depressed children/adolescents with non-depressed controls and (b) reported associations between vmHRV and depression severity.

Results: The search update identified 5 additional studies for group comparison (k = 9 studies in total, n = 608 individuals in total) and 15 additional studies for correlational meta-analysis (k = 21 studies in total, n = 4224 individuals in total). Evidence was found for lower resting-state vmHRV in clinically depressed children/adolescents compared to healthy controls (SMD = -0.593, 95 % CI [-1.1760; -0.0101], I = 90.92 %) but not for a significant association between vmHRV and depressive symptoms (r = -0.053, 95 % CI [-0.118; 0.012], I = 65.77 %). Meta-regression revealed a significant association between depressive symptoms and vmHRV as a function of sex.

Limitations: The samples considered are highly heterogeneous. Data on the longitudinal association between vmHRV and depression are currently lacking.

Conclusion: The present findings support the use of vmHRV as a biomarker for clinical depression in children/adolescents.