Antidepressants affect on suicide rates limited by low usage

The use of antidepressants is likely to account for only 10 per cent of the fall in suicide rates among middle aged and older people, suggests a large study in the Journal of Epidemiology and Community Health.

Globally, more than 800,000 people commit suicide every year.

Rates have been falling in many countries, a factor that has been associated with better recognition of depression and the increasing use of antidepressants, particularly the newer selective serotonin reuptake inhibitors (SSRIs).

But research involving more than 2 million Danes aged 50 and above and living in Denmark between 1996 and 2000, throws this into question.

The researchers assessed changes in the numbers of middle aged and older people committing suicide during this period and the types of antidepressant drugs they had been prescribed.

Only one in five of those committing suicide was actually taking antidepressants at the time of death.

Suicide rates in older men fell by almost 10 per 100,000 of the population during this timeframe, but among recipients of antidepressants, the fall was less than one. However, the authors report that while individuals taking antidepressants do contribute to the decline in the overall suicide rate in the study this was offset by the increase in the percentage of people being prescribed antidepressants.

An added complication is that antidepressants are being increasingly prescribed for conditions not usually associated with a heightened risk of suicidality such as pain, irritable bowel syndrome and sexual dysfunction. This may have diluted the impact of antidepressants in the the study's results. The authors state that it is important that future studies "assess the diagnoses for which the medicine was prescribed."

For older women, only 0.4 of the 3.3 fall per 100,000 of the population was accounted for by those being treated with antidepressants.

Overall, treatment type made little difference, although rates among men taking SSRIs were slightly higher than among those taking tricyclics.

Suicide rates were five to six times higher among those taking antidepressants than those who were not which is not surprising given the majority of those prescribed antidepressants were likely to be at greater risk of suicide than the general population.

The 'other types' antidepressant category also includes individuals receiving combined drug treatments. The higher suicide rate for individuals in this group may reflect more complex or treatment-resistant disorders.

Previous Scandinavian and US research has suggested that a fivefold increase in the use of antidepressants could lead to a 25% decrease in suicide rates, with SSRIs having saved as many as upwards of 33,000 lives, say the authors.

Sales of antidepressants in Denmark have soared from 8.4 per 1000 of the population in 1990 to 52.2 in 2000. And suicide rates among older people have more than halved from 52.2 in 1980 to 22.1 per 100,000 of the population in 2000. Over the same time period there was only a modest fall (pdf) in the United States, abet from a much lower baseline rate.

The authors state that current antidepressant treatment accounts for only a fraction of the falls in suicide rates among older people. But they nevertheless suggest that more should be done to pick up and treat depression among older people.

They conclude by saying "it is highly relevant that only a small proportion, one in five, were at the time of death considered as being in treatment. This observation is supported by forensic data showing that 20% of examined suicides of a wider age range had traces of antidepressants in postmortem toxicology.

"It is estimated that more than 70% of older adults who die by suicide suffer from mood disorders. Given that antidepressants are the most commonly applied therapy for mood disorders, our findings suggest that a strikingly large proportion of the older adults dying by suicide are not receiving the treatment indicated."

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Erlangsen A, Canudas-Romo V, Conwell Y. Increased use of antidepressants and decreasing suicide rates: a population-based study using Danish register data. J Epidemiol Community Health. 2008;62:448-454   [Abstract | Full text]