A popular, anciently rooted idea about clinical depression—that it results from a chemical imbalance—still finds its way into many news reports, a study has found.
There’s just one problem: the claim has little or no basis, the study’s authors say. In fact, the mainstream scientific view is that depression’s causes are simply unknown.
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Absinthe Drinker by Pablo Picasso (1901). |
The study is taking on added relevance in light of other new research casting doubt on the efficacy of popular anti-depression medications. Pharmaceutical companies sometimes advertised those drugs as correcting a chemical imbalance.
In the new study, researchers contacted journalists who had written articles about depression being caused by a chemical imbalance—or, as a modern version of the theory holds, by lack of a substance called serotonin.
But asked where they had found that information, reporters couldn’t provide scientific evidence for the claim, according to the investigators.
The researchers, with Florida State University and Lincoln Memorial University in Tennessee, said they spent about a year in late 2006 and 2007 monitoring daily news for articles that included such statements, and contacting the authors. The findings are published in the research journal Society.
The concept of depression as a chemical imbalance is traceable to the ancient Greeks, who believed health and illness arise from correct or incorrect proportions of four substances known as humors.
The notion found an echo in the more modern hypothesis developed in the 1960s, that lack of serotonin in the brain causes depression. But this, too, remains unproven, according to the researchers: its main support, in fact, came from the claimed efficacy against depression of drugs meant to correct this imbalance.
But recent research found the drugs, known as Selective Serotonin Reuptake Inhibitors or SSRIs, were less effective than previously believed.
“The media’s presentation of the theory as fact is troublesome,” said Jeffrey R. Lacasse of Florida State, one of the researchers. In reality, “there are few scientists who will rise to [the theory’s] defense, and some prominent psychiatrists publicly acknowledge that [it] is more metaphor than fact.”
The real cause of depression is unknown, said Leo and Lacasse, a conclusion also echoed in standard medical texts such as The Diagnostic and Statistical Manual of Mental Disorders—used by most psychiatrists—and The Merck Manual of Diagnosis and Therapy.
A review of clinical trials published in the journal PLoS-Medicine last month concluded that much of the perceived efficacy of the more common SSRIs was due to the placebo effect, in which people feel better simply because they know they’re being treated.
Other studies indicate that for every 10 people taking an SSRI, only one or two really benefit from it, according to Lacasse and his co-author, Jonathan Leo of Lincoln Memorial. They have also argued that even if SSRI’s did cure depression, this wouldn’t establish that lack of serotonin causes it, any more than aspirin’s efficacy against headaches “proves” that lack of aspirin causes headaches.
Courtesy Florida State Universityand World Science staff