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Monday, August 24, 2009

U.S. Antidepressant Use Doubled in A Decade

The proportion of Americans using antidepressants in a given year nearly doubled from 5.8% in 1996 to 10.1% in 2005, according to a paper just published: National Patterns in Antidepressant
Medication Treatment
, by Mark Olfson and Steven Marcus.

That means about 15 million more Americans were medicated in '05 than a decade previously. A huge increase in anyone's book. But the doubling in antidepressant use is not the only interesting result in this paper. In no particular order, here are some other fun facts -
  • Women are twice as likely to use antidepressants as men (female 13.4% vs male 6.7% in 2005); the ratio was the same in 1996. Studies consistently find that Western women are about twice as likely to report suffering from depression and anxiety disorders as men are. But these kinds of studies rely on self-report so this could merely mean that women are more willing to talk about their problems. This data suggests that they also seek treatment about twice as often.
  • The peak age bracket for antidepressants is 50-64, with 15.5% yearly use. This is more than double the rate in the 18-34 bracket. This surprised me, maybe because of the influence of books like Prozac Nation (tagline - "Young and Depressed in America"). So, it looks like the increasing use of antidepressants is not because younger people, having grown up in the "Prozac Era", are more accepting of them.
  • Antidepressants are a white thing - 12.0% of whites take them vs. about 5% of blacks and Hispanics. But it would be interesting to see a regional breakdown here. Are blue-state or red-state whites more likely to be medicated?
  • Family income was not correlated with antidepressant use, but the unemployed were twice as likely to use antidepressants: 22% in '05. This might be because unemployment is bad for your mental health, or because mental illness is bad for your employment prospects. Or both.
  • One of the questions in the survey asked people to rate their own mental health. Over 90% of Americans said it as "good", "very good" or "excellent" - including 80% of antidepressants users. This really surprised me, and suggests that these drugs are being prescribed to people who are not, overall, very unwell.
  • The % of antidepressant users also using an antipsychotic drug rose from 5.5% to 8.9% in 2005. Given that the number of users also doubled, this means the number of Americans using an antipsychotic as well as an antidepressant increased by a factor of more than 3. This is worrying since antipsychotics are generally the worst psychiatric drugs in terms of side effects. While there is evidence that some of the newer antipsychotics can be of use in depression as an add-on to antidepressants, this is controversial and it's not clear that they're any better than the older alternatives, such as lithium.
Overall, this report verifies that antidepressant use has risen dramatically over the past several years. This is hardly news, but the magnitude of the increase is still startling.

What makes it especially interesting is that nothing much happened between 1996 and 2005 in terms of new antidepressants. A couple of new SSRIs, such as citalopram, were approved for sale in the US. But these drugs are very similar to Prozac (fluoxetine) which has been around since '87. Remeron (mirtazapine) hit the market in '96, but it's never been nearly as popular as the SSRIs.

So the change was a change in behaviour, a cultural or social phenomenon. For some reason, America decided to take more antidepressants. Books could be written on why this happened, and I hope they will be, because it's an important topic. But here's my personal take: the main reason why people are taking more antidepressants is that the popular concept of "depression" has become more broad. People have become more willing to label their experiences as "depression" and seek medical treatment. The notion that mental illness is extremely common - the one in four meme - is one aspect of this.

Finally, the inevitable caveats. The data here come from the Medical Expenditure Panel Surveys (MEPS) which were household surveys of "national probability samples of the US civilian noninstitutionalized population". This means that military personnel, the homeless, prisoners, and (presumably) illegal immigrants weren't included. And not everyone agreed to take part; the response rate was 70% in '96 but dropped to 60% in '05. On the other hand, the samples were extremely large (28,000 in 2005).

ResearchBlogging.orgOlfson M, & Marcus SC (2009). National patterns in antidepressant medication treatment. Archives of general psychiatry, 66 (8), 848-56 PMID: 19652124

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