Medical Matters: Following the links between antidepressant use and heart disease

The recent flurry of excitement about coffee preventing heart disease illustrated two important points: suspected “causes” of coronary heart disease can be rehabilitated over time; and beware the inflated and sometimes misleading press release or report attributing causation to risk factors when a possible association between a risk factor and outcome is really what new research is suggesting.

"Moderate coffee consumption lessens risk of clogged arteries and heart attacks" was the PR headline over new research published in the medical journal Heart. Subsequent reports appeared to offer coffee drinkers a guilt-free passage to a five-cups -a-day caffeine fix, complete with a promise of avoiding heart attacks and strokes in future.

In fact, the researchers were careful to point out that “further research is warranted to confirm our findings and establish the biological basis of coffee’s potential preventive effects on coronary artery disease”. They specifically noted they could not recommend drinking coffee in order to prevent cardiac disease.

Contrast this with research presented at the American College of Cardiology meeting in San Diego on March 15th. It concerned growing evidence of a link between heart disease and depression. Here is the PR blurb sent to journalists before the presentation: “A new study by researchers at the Intermountain Medical Center Heart Institute has found that screening for and treating depression could help to reduce the risk of heart disease in patients with moderate to severe depression.”

Note the use of “could” and avoidance of a “treating depression reduces heart disease” oversimplification. Curious readers may wish to do online research to see how the world media reports the research. I’ll be surprised if you find much in the way of hyperbole.

Reportage issues aside, the study is quite interesting. The three-year questionnaire study of 5,000 patients with moderate or severe depression found that those treated with antidepressants seemed to show lower rates of death, coronary artery disease and stroke than people who did not take the drugs.

For patients with mild depression, there was no associated benefit. Somewhat intriguingly, there appeared to be no benefit in patients with any degree of depression who were taking cholesterol-lowering drugs in combination with antidepressants. The analysis accounted for standard cardiovascular risk factors such as diabetes, smoking and hypertension. However, there are some important caveats: because the study included only information available in patients’ health records, the researchers were unable to account for other factors such as level of physical activity, changes in lifestyle habits or other mental health treatments such as psychotherapy.

Lead author and cardiovascular epidemiologist Heidi May says the link between the drugs and a reduction in cardiac disease could be connected to behavioural changes.

“Antidepressants might have relevant physiological benefits, but I also think the behavioural changes that improve a person’s mood can also improve cardiovascular health,” she said. “This study demonstrates the importance of evaluating patients for depression, not only in terms of improving their mood but reducing their risk for heart disease.”

It is well established that major depressive illness is associated with cardiovascular disease, with 2012 figures suggesting some 17 per cent of heart attacks and 23 per cent of strokes occur in people with significant depression. The condition has been shown to have physiological effects that are detrimental to heart health as well as behavioural responses that encourage heart disease.

Depressed patients with coronary heart disease have reduced heart-rate variability and have higher levels of blood markers for inflammation and clotting. They are also less inclined to exercise, more likely to smoke and are less inclined to adhere to cardiac treatment.

While more research is needed to firm up any link between antidepressant use and reduced heart disease, at the very least we can say screening people at high risk of heart disease for depression should be a priority.

mhouston@irishtimes.com muirishouston.com