Credit: Flickr user e3000
Conventional wisdom says that gifted artists like Vincent van Gogh and Sylvia Plath had something in their constitution that made them much more susceptible to depression, and thus, to suicide. One of the smartest people I ever knew, a former high school classmate who was also a world-class rower, took his own life as pressures for perfection at his Ivy-League university became too much for him. Such stories, painful and tragic, lend credence to the belief that smart people are more likely to commit suicide. But do we remember these stories because they are commonplace, or are they notable only because they are also actually rare?
Because of the relative rarity of suicide, researching its causes is problematic. Most studies therefore investigate attempted suicide, which is much more common. Since attempted suicides are very strongly correlated with actual suicides, they can serve as a reasonable proxy measurement.
Two studies by Martin Voracek seem to uphold the notion that more intelligent people are more likely to commit suicide. Voracek looked at national suicide rates and average IQ, and found that countries with higher average IQs also had higher suicide rates. But a study released last week suggested the opposite might be true. A team led by G. David Batty looked at military conscription records of over 1 million Swedish men, and found that those with higher IQs were significantly less likely to be admitted to a hospital for a suicide attempt than those with lower IQs. Even after adjusting for socioeconomic status, education, and a variety of other factors, those in the top 10 percent of IQ scores were about four times less likely to attempt suicide than the bottom 10 percent. The researchers considered men with schizophrenia or other psychoses separately, and found no correlation between IQ and suicide attempts—the relationship between IQ and suicide only held for men who were otherwise relatively mentally stable. The research was published in the British Medical Journal. While it’s statistically possible for both the Voracek and Batty studies to be valid, these seemingly contradictory results suggest that the roots of suicide are more complex than the responses to a standardized test.
Though the Batty et al. study controlled for psychoses, it did not control for clinical depression, which for the most part is not a psychotic disorder, but is associated with suicide. Even more troubling are some recent studies suggesting that adolescents who take antidepressants may be at a higher risk for attempting suicide. Could it be that the treatment, rather than the depression itself, is responsible for depression-related suicides? Nestor L. Lopez-Duran, a child psychologist at the University of Michigan, blogged about one such study last month. A team led by Sebastian Schneeweiss looked at the medical records of over 21,000 adolescents aged 10 through 18 during the year following the onset of antidepressant therapy. They found that regardless of which antidepressant the children used, rates of suicide attempts were similar. The research was published in Pediatrics. Earlier research had found that adolescent usage of a particular class of antidepressant, selective serotonin reuptake inhibitors (SSRIs) such as Prozac, led to more suicide attempts than in adolescents who received placebos, suggesting that it was indeed the treatment, and not the illness, that led to suicide attempts. Lopez-Duran says that the effect may due to the fact that antidepressants all lead to more activity and increased self-confidence, which might make acting on a suicidal impulse more likely.
But the anonymous neuroscientist who blogs as “Neuroskeptic” says the initial evidence that SSRIs cause suicide attempts isn’t as straightforward as it seems. For ethical reasons, individuals with suicidal tendencies are excluded from clinical drug trials, which means the absolute numbers of suicide attempts in these studies are usually very small. Completed (fatal) suicides are typically measured in single digits. Where effects are found, they are tiny, and they may not correspond to the real world where suicidal individuals are given antidepressants. For those cases, we can only turn to observational studies like the one cited by Lopez-Duran.
Neuroskeptic points to a review of six such studies published last week in Australasian Psychiatry. Michael Dudley, Robert Goldney, and Dusan Hadzi-Pavlovic found that in those studies, just 9 of 574 suicide victims had been on SSRIs at the time they died. In other words, only a very small portion of actual suicides among depressed individuals can be associated with SSRIs. Despite the recent explosion in the use of antidepressants, we haven’t seen much change at all in suicide rates, so the effect of SSRIs and other antidepressants on suicide must indeed be small.
Other factors, such as Voracek’s nation-by-nation differences in suicide rates, or Batty’s IQ study, offer much more dramatic and robust results. On the other hand, while people don’t have much control over their IQ or what country they live in, they can control what medications they take. The decision of whether to take medication to treat depression is a multi-layered one. In the end, we can’t say for certain if these antidepressants would have saved my friend (or Plath or van Gogh) or hastened his demise. Given the difficulty of conducting research on the topic, it’s an uncertainty we may have to live (or die) with for a very long time.
Dave Munger is editor of ResearchBlogging.org, where you can find thousands of blog posts on this and myriad other topics. Each week, he writes about recent posts on peer-reviewed research from across the blogosphere. See previous Research Blogging columns »
Originally published June 9, 2010