Middle-age men who use antidepressants are more likely to have a narrowing of blood vessels, increasing the risk of heart attacks and strokes, than those who do not use the medications, according to a study presented.
A study of twins found evidence of atherosclerosis, as measured by the interior thickness of the carotid artery, regardless of the type of antidepressant taken.
Antidepressant use was found to cause a 37-micron increase in carotid artery thickness, or roughly 5%, according to the study of more than 500 male twins with a mean age of 55 which was presented at the American Cardiology scientific meeting in New Orleans.
In 59 sets of twins in which one brother was taking an antidepressant and the other was not, the brother taking the medication had on average a 41-micron thicker inner lining of the artery, the research found.
As each year of life has been associated with a 10-micron increase in carotid artery thickening, the brother taking the antidepressant had arteries that were essentially four years older than those of his non-medicated twin.
Previous studies have linked depression to a heightened risk of heart disease, but the condition was not deemed a significant predictor of artery thickening in the study.
"Because we didn't see an association between depression itself and a thickening of the carotid artery, it strengthens the argument that it is more likely the antidepressants than the actual depression that could be behind the association," said Dr Amit Shah, cardiology fellow at Emory University in Atlanta, who presented the data.
Side effects we can't feel
"This study reminds us that medicines often have side effects we can't feel, and we should always take that into account. These drugs provide a lot of benefit, but should be considered on a case-by-case basis," Dr Shah said.
Dr Shah hypothesised that the raising of levels of certain brain chemicals, such as serotonin and nor epinephrine, through antidepressant use may cause blood vessels to constrict, leading to decreases in blood flow to organs and higher blood pressure - a risk factor for atherosclerosis.
"Because this was a twin study, we had a very well controlled analysis comparing brothers who are anywhere from 50% to 100% genetically similar and were raised in the same household," Dr Shah said. (Reuters Health/ March 2011)