MEDICAL MATTERSThere is often a strong link between heart disease and severe depression
THE RECENT controversy concerning the value or otherwise of antidepressant drugs has stimulated some interesting comment. Much of it has focused on the overuse of antidepressants in mild depression and the unavailability of cognitive behavioural therapy (CBT) as a first-line treatment.
But there is another aspect to depression: that is how, in its more severe forms, the illness can produce some marked physical effects. Although the diagnosis is primarily made in the presence of defined psychological symptoms, there are many physical symptoms associated with major depression. Patients commonly report weight loss, sleep disturbance, tiredness, headache, nausea, constipation and other physical effects.
For anyone who questions the physical nature of depression, an encounter with a very severely depressed person will eliminate all doubt. Typically, they appear zombie-like and extremely fatigued. Their movements will be very slow; they do not seem to hear what you are saying because they literally do not have the energy to focus on it. And their weight loss will be striking, with deeply sunken eyes and protruding ribs.
Modern neuroimaging techniques clearly illustrate actual physical changes in the mood system in the brains of depressed people, supporting the concept of a physical, as well as a psychological basis for depression.
Probably one of the most powerful arguments for depression having a physical component is the strong link between it and heart disease. About one in five patients with coronary heart disease (a blockage in the vessels supplying the heart) are clinically depressed.
And people with depression are now known to have an increased risk of developing coronary heart disease, while those with depression and established heart disease have a greater risk of developing further cardiac complications.
Last week, researchers from Washington University School of Medicine in St Louis reported a two- to four-fold increase in a person's risk of dying following a heart attack if they were also depressed. Dr Robert Carney, professor of psychiatry at the university, and his colleagues followed more than 750 heart-attack patients for five years.
During this time, 106 patients died. Of these 62 has been diagnosed with depression, while 44 had not. The researchers adjusted for risk factors, such as smoking, high blood pressure and diabetes, to focus on the statistical impact of depression on its own.
What about people with stable coronary heart disease? A Canadian study, published in January, found that stable cardiac patients with either major depression or a serious anxiety disorder had double the risk of a cardiac event such as a heart attack.
Unfortunately, a recent paper in the British Journal of Psychiatry suggests the most obvious solution to the problem - the prescription of anti-depressants for patients who are depressed after a heart attack - does not work. The Mind-It study found no difference in cardiac prognosis between a group of patients treated with an antidepressant and those given "usual care". This does not rule out a beneficial effect in individual cases, but it does dash hopes for a quick-fix solution.
This is something that should not surprise us. Modern antidepressants are effective in about one-third of patients. Others respond better to a talking therapy, such as cognitive behavioural therapy (CBT), while still more do well with a combined approach.
It is also possible that the type of depression experienced after a heart attack may be different to a more "typical" depression. For example, could there be a "cardiotoxic" subtype of depression?
The whole area of depression causing heart disease and the psychological fallout from an acute coronary event is the subject of much ongoing research activity. Given the role of adrenaline and other chemicals in both diseases and the possibility of an inflammatory process common to both, it is likely that definitive links will emerge.
In the meantime, people with recurrent depression should ask to be monitored for heart disease, while those who have recently had a heart attack, cardiac stent or bypass need psychological assessment and follow-up in the months after the event.
Dr Houston is pleased to hear from readers by e-mail at mhouston@irish-times.ie but regrets he is unable to reply to individual medical queries