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Middle-aged men who take antidepressants, scientists presenting a paper at the scientific meeting of the American College of Cardiology in New Orleans tell us, are at greater risk of heart attacks and strokes.

Scientists Study Effects on Antidepressants in Twins

Studying 513 twin males who were listed in the Vietnam Era Twin Registry, Dr. Amit Shah, a Florida gastroenterologist currently a cardiology fellow at Emory University in Atlants, found that 16 percent, or about 160 men, were taking antidepressant medication. Some of these twins took older medications not associated with cardiovascular problems, but about 100 of these men were taking modern medications in the same class as Paxil and Prozac.

Of these approximately 100 men, 59 did not have brothers also taking SSRI antidepessants. This allowed the doctors to examine the brothers to see if antidepressant medication possibly caused risk of heart attack and stroke.

Amit found that the men who were prescribed the drugs for depression had thicker linings of their carotid artery walls. Thicker artery walls, the reasoning goes, are stiffer artery walls, and stiffer artery walls are more likely to be constricted and less likely to be dilated, catching clots that cause heart attacks and ischemic (clot-induced) strokes.

It's normal for artery walls to get thicker as we age. On average, an arterial wall gets 10 microns thicker  every year. That's a very, very small addition to the thickness of the wall. A micron is a millionth of a meter or a thousandth of a millimeter. It's about 0.00004 inches.

In the 59 sets of middle-aged, male twins in which one twin took an antidepressant and the other twin did not, the drug-taking twin had an arterial wall that was an average of 41 microns thicker than his brother's. That's 41/1,000,000 of a meter or 0.0016 inches. Is that really enough to make a difference?

The carotid artery, for instance, is normally up to 1 mm in diameter. That's about 250 times wider than the difference in arterial thickness caused by taking medication, even over a period of years. Antidepressants clearly do not cause "clogged" arteries. So what is the real relationship between using antidepressants and cardiovascular catastophes?

The doctors gathered at the American College of Cardiology event agreed that this study does not show that antidepressants cause atherosclerosis. The doctors also agreed that depression itself does not cause atherosclerosis. Dr. Shah commented that thickening the intima, or lining, of the carotid artery by even this tiny amount might increase the risk of heart attack by 1.8 per cent, but the other studies that have made their way into the literature suggest that using antidepressants actually decreases the risk of heart attack by up to 59%. Taken as a whole, the scientific literature makes very little sense, unless one takes into consideration that antidepressant drugs are not always prescribed according to manufacturer and FDA guidelines.

The real cause of heart attack and stroke in SSRI users likely is not thicker artery walls, it is probably serotonin syndrome. Serotonin elevates mood. It also causes the muscles underlying artery walls to constrict, temporarily tightening the artery and blocking blood flow. Serotonin syndrome most commonly occurs when doctors prescribe multiple medications for depression or when they increase the dosage. It isn't the medication that causes the risk of heart attack or stroke. It's how it's prescribed.

  • Pizzi C, Rutjes AW, Costa GM, Fontana F, Mezzetti A, Manzoli L. Meta-analysis of selective serotonin reuptake inhibitors in patients with depression and coronary heart disease. Am J Cardiol. 2011 Apr 1, 107(7):972-9. Epub 2011 Jan 20.
  • Photo courtesy of mikael altemark by Flickr :