Common antidepressants can impact the ability to learn from our surroundings

Escitalopram is one of the more tolerable selective serotonin reuptake inhibitors (SSRIs), used clinically over a longer period of time to treat depression. However, between 40% and 60% of patients taking SSRIs experience “dulling,” described as the feeling that their emotions are dulled and they don’t find pleasure in doing the things they once did, according to researchers. researchers who published the results of a recent study in Neuropsychopharmacology.

Researchers have found that SSRIs like escitalopram affect reinforcement learning, a behavioral process that allows us to learn from our environment. Their impact on learning could explain why nearly 50% of users feel emotionally dulled.

“They take away some of the emotional pain that people who have depression feel, but unfortunately it seems they also take away some of the pleasure. From our study, we can now see that it’s because ‘they become less responsive to rewards, which provide important feedback,’ said Barbara Sahakian, lead author, Department of Psychiatry, University of Cambridge, and Fellow at Clare Hall, in a recent press release.

But the researchers wanted to understand its long-term effect on cognitive well-being. Teams from the University of Cambridge and the University of Copenhagen recruited 66 volunteers in a study that assessed how escalopram would affect healthy individuals over several weeks. They would assess the impact of SSRIs by asking participants to take a series of cognitive tests after at least 3 weeks.

About half of the participants (32 participants) received escitalopram while the control group received a placebo (34 participants). After 21 days, participants completed self-report questionnaires that assessed cognitive functions such as learning, inhibition, executive function, reinforcement behavior, and decision making.

The results suggest that escitalopram affected participants’ sensitivity to rewards. This means that participants did not rely on feedback (in the form of rewards) as much to guide their decision-making as the control group. However, the SSRIs examined did not significantly decrease “cold” cognitive skills, such as attention and memory, or emotional (hot) cognition, compared to people not on SSRIs, researchers say. .

Researchers tested cognitive function with a “probabilistic inversion test”, showing participants 2 stimuli, A or B. The likelihood of reward was higher if participants chose option A, with a 4 in 5 chance of reward , against a 1 in 5 chance of being rewarded with option B. In addition, participants had to observe and learn these rules themselves. They were also responsible for adapting when the probabilities of rewards changed.

“Our results provide important evidence for the role of serotonin in reinforcement learning. We are following this work with a study examining neuroimaging data to understand how escitalopram affects the brain during reward learning,” said said co-first author Christelle Langley, Department of Psychiatry, in the press release.

Reference

Cambridge University. Scientists explain the emotional “dullness” caused by common antidepressants. January 22, 2023. Accessed January 23, 2023. https://www.eurekalert.org/news-releases/976960