Heart rate variability alterations in late life depression: A meta-analysis

Objective: There is strong evidence for a bi-directional relationship between heart-health and depression in later life, but the physiological mechanisms underlying this relationship remain unclear. Heart rate variability is one promising factor that might help explain this relationship. We present results of a meta-analysis that considers heart rate variability alterations in older adults with depression. Methods: Literature search of Embase, Psychlnfo and Medline revealed five clinical studies and six observational studies that examined the relationship between heart rate variability and depression in adults with a mean age over 60. These studies were included in this meta-analysis. Results: Heart rate variability was reduced among older adults with clinical depression (N = 550), relative to healthy controls (Hedges' g = -0.334, 95%CI [-0.579, -0.090], p =.007). When high-frequency and low frequency heart rate variability were investigated separately, only low-frequency heart rate variability was significantly reduced in depressed patients (Hedges' g = 0.626, 95%CI [-1.083, -0.169], p =.007). A similar but weaker pattern of results was found in the observational studies. Most findings remained significant among unmedicated depressed older adults. Limitations: Evidence of effect-size heterogeneity was found in the clinical studies, indicating the need for more well-designed research in the area. Conclusion: Heart rate variability is reduced among older adults with depression, and this effect is not fully attributable to antidepressant medication use. Specifically, low-frequency heart rate variability may be reduced in depressed older adults. Heart rate variability warrants further attention, as it could help inform research into the prevention and treatment of depression in later life.