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Study: media misconstrues blues as “chemical imbalance”

March 4, 2008
Courtesy Florida State University
and World Science staff

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.

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.

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An ancient and still popular 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 notion has little or no basis, the study’s authors say. In fact, the mainstream scientific view is that depression’s causes are simply unknown. 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 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 rooted in ancient Greece. The Greeks believed health and illness arise from a balance or imbalance among four substances known as humors. The notion found an echo in a more modern hypothesis developed in the 1960s, that lack of serotonin in the brain causes depression. The trouble is that it 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 the drugs, known as Selective Serotonin Reuptake Inhibitors or SSRIs, recently turned out to be largely ineffective. “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 Public Library of Science-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, 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.