believe that the purpose of a study (Kemp et al 2014) was to improve understanding of how people respond to learning the cause of their depression. They were administered the Rapid Depression Test (RDT), which they were deceived into believing is a "test of neurotransmitter levels whose results would allow participants to determine whether or not their depressive episode(s) were caused by a chemical imbalance in the brain".
The test entailed swabbing the inside of the participants' cheeks with a sterile cotton swab and placing the cotton swab into a sterile collection container. Participants were told their saliva sample would be tested in the lab. The experimenter returned 10 minutes later with the results.
In the chemical imbalance condition, participants were informed that test results indicated that their past/current depression was caused by an imbalance in the neurotransmitter serotonin. Participants were presented with a bar graph of their test results depicting very low serotonin levels relative to levels of other neurotransmitters, all of which were in the normal range. Participants in the control condition, on the other hand, were told their past/current depression was not the result of a chemical imbalance, based on purported test results (and a corresponding bar graph) indicating that all neurotransmitter levels were in the normal range.
The chemical imbalance test feedback made participants significantly more likely to attribute their depression to chemical imbalance, demonstrating that the intervention was effective. Self-stigma was unaffected but chemical imbalance feedback made participants significantly more pessimistic about prognosis. There was some evidence of lowered perceived ability to regulate negative mood states. Participants in the chemical imbalance condition rated pharmacotherapy as more likely to be effective than psychotherapy. By contrast, expectancies for pharmacotherapy and psychotherapy did not differ significantly in the control condition.
The authors conclude that doctors may be causing harm by encouraging belief in chemical imbalance. The theory may be used as a means of getting patients to take their medication (eg. see my eletter). It can be a surprise to patients when they discover the theory has never been proven. They might be even more upset when they realise they might have done better not to believe it.
(With thanks to blog by Kermit Cole on Mad in America)