Antidepressants may improve brain function
Researchers have found that SSRI (Selective Serotonin Reuptake Inhibitors) antidepressants have the potential to improve certain cognitive functions, such as verbal memory. They measured brain function in patients before and after taking the SSRI escitalopram and correlated this to a drop in the level of one of the serotonin receptors in the brain and to cognitive improvements during treatment. This work is presented for the first time at the ECNP Conference in Milan, after recent publication in the journal Biological Psychiatry.
Serotonin is often described as a ‘feel good’ chemical, and higher levels of serotonin circulating in the brain contribute to a sense of well-being, and can ease clinical depression in most sufferers. There are several serotonin receptors in the brain, and all will serve to regulate well-being by regulating circulating serotonin’s interaction with the brain. However, this work concentrated on only one serotonin receptor, the 5HT4 receptor.
The researchers began by scanning the brains of 90 depressed patients, to measure the quantity of 5HT4 receptor which serotonin binds to. At the same time, patients were given a series of tests to measure mood and cognitive abilities.
Patients were given daily doses of escitalopram, and at the end of an 8-week period, 40 patients were rescanned to measure the quantity of 5HT4 receptor in the brain. The mood of the patients had improved, but the team also found that the levels of 5HT4 receptor had dropped by around 9% possibly due to adaptations to increased levels of serotonin. When they asked these patients to undertake more cognitive tests, they found that their performance had improved, so that the less the 5HT4 receptor had changed the better the cognitive outcome. This phenomenon was particularly prominent for the ability to recall words.
“This is potentially significant” said researcher Vibeke Dam (Copenhagen University Hospital, Rigshospitalet, Denmark), “It seems that the SSRI medication contributes to an improvement on cognitive function, at the same time as helping improve mood. Our work ties the improvement in cognitive function to the specific 5HT4 receptor and suggest that direct serotonin 4 receptor stimulation may be in important pro-cognitive target to consider in optimizing outcomes of antidepressant treatment. It also reinforces the idea that serotonin is crucial to mood improvement.
Co-researcher Vibe Froekjaer (Copenhagen University Hospital, Rigshospitalet, Denmark), added, “This is a first result, so we need to do a lot more work to look at the implications. Poor cognitive function is very hard to treat efficiently and may require extra treatment. This work points to the possibility of stimulating this specific receptor so that we can treat cognitive problems, even aside from whether or not the patient is has overcome the core symptoms of depression”.
The researchers note that this was a real-world study, so there is no placebo control.
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