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02-12-2008 | Mental health | Article

Antidepressants may reduced heart rate variability


Free abstract

MedWire News: Individuals diagnosed with depression appear to have significantly lower heart rate variability than other people, say Dutch investigators in findings that suggest the association may be due to the effect of antidepressants.

Previous studies have indicated that depression is associated with lower heart rate variability, which is a prognostic risk factor for cardiovascular disease. In addition, one of the major determinants of reduced heart rate variability may be low cardiac vagal control, which is also associated with impaired social engagement and flexible adjustment to environmental demands.

To investigate further, Brenda Pennix, from VU University Medical Center in Amsterdam, and colleagues assesses data on 2373 participants in the Netherlands Study of Depression and Anxiety, of whom 774 were diagnosed with remitted major depressive disorder (MDD), 1075 were diagnosed with current MDD, and 524 acted as controls.

The patients underwent 1.5 hours of ambulatory electrocardiograms and thorax impedance testing, determining the standard deviation of normal-to-normal beats (SDNN) and respiratory sinus arrhythmia (RSA), which indexed cardiac vagal control.

The overall average age of the participants was 41.6 years, 66.8% were female, and 50.2% had <12 years education. Depressed individuals were more likely than nondepressed individuals to be female, have less education, have higher body mass index scores, engage in less physical activity, smoke, drink less alcohol, have more heart disease and other chronic diseases, use antidepressants, and have higher depressive symptom scores.

While there were no significant differences between depressed and nondepressed individuals in terms of heart rate, remitted and current MDD patients had significantly lower SDNN and RSA values than controls, at reductions of 3.1–5.7 ms and 5.1–7.1 ms, respectively, for SDNN and RSA.

These associations were unaffected by comorbid anxiety and lifestyle, the team notes in the Archives of General Psychiatry.

In contrast, the association with SDNN was completely removed and the association with RSA markedly reduced after accounting psychoactive medication. Compared with controls and unmedicated depressed individuals, depressed patients given selective serotonin reuptake inhibitors, tricyclic antidepressants, or other antidepressants had significantly shorter SDNNs and RSAs, at an effect size of 0.207–0.862.

“Our findings demonstrate that depressed persons have lower total heart rate variability with lower cardiac vagal control, but these effects are mostly derived from depressed persons using antidepressants,” the team writes.

“Because it has been widely established that lowered heart rate variability is a risk factor for cardiovascular morbidity and mortality, our findings could be of importance to clinical practice.”

By Liam Davenport