Washington, Mar 5 (UNI) Depressed heart attack patients have a higher risk for sudden death in the months following a heart attack, research says.
''There's a two-to-four fold increase in a person's risk of dying following a heart attack if they also happen to be depressed,'' said Robert M Carney, PhD, lead author of the new study and professor of psychiatry at Washington University School of Medicine in St Louis, which conducted the study.
''Previously we thought the impact of depression was strongest for the first three to six months following a heart attack and then gradually dropped off within a couple of years. Instead, we found the effect lasts for at least five years,'' he added.
Dr Carney, with colleagues from Duke University Medical Center, Harvard University, Yale University, the National Heart, Lung and Blood Institute (NIH) and the Mayo Clinic, followed more than 750 heart attack patients for five years.
The study, to be published in the Journal of Affective Disorders, found that in the five years following a heart attack, 106 patients died. Of those, 62 had been diagnosed with depression, while 44 had not.
In gauging the effects of depression, the investigators also considered other risks including age, smoking, hypertension, gender and diabetes. Some of those factors, like younger age and female gender, lowered mortality risk. Smoking and diabetes tend to raise the risk of dying, it added.
Dr Carney said his team used statistical methods to evaluate the ways in which the various factors influenced mortality risk. Then they removed the influence of all other factors from the risk equation in order to consider the statistical impact of depression itself.
''We found that after adjusting for those risk factors, depression continues to play a statistically significant role,'' Sciencedaily quoted him as saying.
''One possible explanation for depression's lingering influence on mortality is its recurring nature. Because the disorder can come and go over many years, it also may continue to increase the risk of death for many years,'' he added.
''People typically are depressed for a while, then they'll either get better with treatment or it may subside on its own,'' Dr Carney explained.
''But depression can always recur, and we think that because it is a recurring problem, whatever depression is doing to mortality risk after a heart attack, it continues doing for quite a long time,'' he added.
Dr Carney's team also found that any clinically relevant depression increased the risk of death in heart attack patients.
The risk was elevated both for patients with major depression, which requires the presence of five or more symptoms, and minor depression, which requires between two and four symptoms for diagnosis. Major depression was associated with higher risk, but minor depression also associated with a significant increase in mortality risk, the report added.
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