Depressed elderly people are more likely to suffer heart disease not because of their depression, but apparently due to antidepressant medications, according to a study published in Psychological Medicine.
In the study, University College Dublin researchers analyzed data on 4,750 participants from the Irish Longitudinal Study on Ageing. Depression has in recent years been strongly linked to heart disease, but it was often not clear why, so they examined 80 participants with depression and 185 who were not depressed, all of whom were taking antidepressants. They compared these people with 4,107 controls who were not depressed and not taking antidepressants. They also compared all three groups to 317 depressed participants who were not taking antidepressants. In all groups they measured heart rate variability (HRV), because reduced HRV is a known risk factor for heart disease.
They found that the depressed people who were not taking antidepressants had the same HRV as the people in the main control group. However, the people who were taking antidepressants had reduced HRV, regardless of whether they were depressed or not.
“In linear regression analysis adjusted for relevant factors all antidepressants were associated with lower measures HRV,” the researchers wrote. “Participants on selective serotonin reuptake inhibitors (SSRIs) had higher measures of HRV relative to participants on tricyclic antidepressants or serotonin-norepinephrine reuptake inhibitors respectively.”
“Our results suggest that reductions in HRV observed among depressed older adults are driven by the effects of antidepressant medications,” the researchers concluded. “SSRIs have less impact on HRV than other antidepressants but they are still associated with lower measures of HRV.”
(Abstract) (Full text) Antidepressants strongly influence the relationship between depression and heart rate variability: findings from The Irish Longitudinal Study on Ageing (TILDA) (O’Regan, C. et al. Psychological Medicine. February 2015. DOI: http://dx.doi.org/10.1017/S0033291714001767)