The Brain Remembers Past Antidepressant Exposure

The discovery was made by an American team of researchers

  Placebo medication usually contains only sugar
The human brain can be tricked into remembering past exposures to antidepressants via a placebo drug, say investigators at the University of California in Los Angeles (UCLA). They recently demonstrated the link in a series of experiments.

The human brain can be tricked into remembering past exposures to antidepressants via a placebo drug, say investigators at the University of California in Los Angeles (UCLA). They recently demonstrated the link in a series of experiments.

One of the things that researchers still do not know about the brain is how it reacts to new intake of antidepressants, after completing a round of medication in the past. The team made its new discovery while seeking to answer this question.

This is a valid concern, especially considering that people who suffer from major depressive disorder (MDD) usually need several courses of medication throughout their lifetime. The condition is very likely to relapse in these individuals, despite doctors' best efforts.

Usually, this can be avoided by finding the correct combination of drugs for each patient, but the process takes a lot of time, and positive results are uncertain even then. For most patients, several rounds of medication remains the only option.

In the new study, the UCLA group determined that the human brain's response to antidepressants is in part dictated by past exposure to such medication. In other words, the brain appears to remember that it took these drugs before.

This was demonstrated in a series of experiments where researchers gave patients harmless placebo pills, rather than real medication. The placebos were made to look like the real pills, but had none of the actual active ingredients.

Full details of the research methodology were published in the March 23 online issue of the esteemed medical journal European Neuropsychopharmacology. The lead author of the investigation was UCLA Semel Institute for Neuroscience and Human Behavior investigator, Aimee Hunter.

The study was carried out on 89 depressed individuals, whose evolution was tracked over a period of 8 weeks. Investigators paid special attention to the brain responses of patients who had been previously exposed to antidepressants, as opposed to those of people who were at their first round of medication.

“The brain's response to the placebo pill seems to depend on what happened previously — on whether or not the brain has ever 'seen' antidepressant medication before. If it has seen it before, then the brain's signature 'antidepressant-exposure' response shows up,” Hunter concludes.

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