A study of orthostatic hypotension, heart rate variability and baroreflex sensitivity in late-life depression.

Background: To determine if subjects with late-life depression have significant cardiovascular autonomic abnormalities (orthostatic blood pressure drop, heart rate variability and baroreflex sensitivity).

Methods: A case-control study, in secondary care facilities, of forty two older (> 60 years) individuals with lifetime history of major depression and 31 age and sex matched comparison subjects. Autonomic function was assessed by measuring postural blood pressure, heart rate variability and baroreflex sensitivity using non-invasive beat-to-beat blood pressure and continuous ECG monitoring (Task Force® Monitor, CNSystems, Graz, Austria). The main outcome measures were maximal reduction in systolic blood pressure with active stand, low frequency and high frequency heart rate variability and baroreflex sensitivity using the sequence method.

Results: Participants with depression had a significantly larger drop in systolic blood pressure on standing from a supine position. Depression was an independent predictor for developing systolic orthostatic hypotension. Depressed participants also had lower low frequency heart rate variability and lower baroreflex sensitivity.

Limitations: This was a cross-sectional and observational study; longitudinal effects or causality cannot be inferred from the findings and we could not distinguish state from trait related changes.

Conclusions: Late-life depression has been associated with vascular disease but previous studies examining vascular risk factors have been inconsistent. Brain MRI white matter hyperintensities are ischemic and increased in late-life depression and associated with orthostatic blood pressure drops in animals. The presence of autonomic abnormalities in late-life depression may partly explain these inconsistencies and be associated with the development of brain white matter hyperintensities.