Antidepressants Make You Numb, Claims New Study

Antidepressants Make You Numb, Claims New Study
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The reason why typical antidepressants cause around half of their users to report feeling emotionally ‘blunted’ has been determined by researchers. A study that was released today shows that the researchers were able to demonstrate that the medications had an effect on reinforcement learning, which is an essential behavioral function that enables us to learn from our surroundings.

According to the National Health Service (NHS), in 2021/22 more than 8.3 million people throughout England were prescribed depressive medication. Selective serotonin reuptake inhibitors are one of the most common types of antidepressants prescribed, especially for patients whose symptoms are chronic or severe (SSRIs). These pharmaceuticals are designed to affect serotonin, also known as the “pleasure molecule,” which is a neurotransmitter that facilitates communication between nerve cells in the brain.

Blunting is one of the negative effects of SSRIs that is often observed by patients. Blunting occurs when patients indicate that they feel emotionally dull and that they no longer find things as enjoyable as they once did. It is estimated that this adverse reaction occurs in between 40 and 60 percent of people who use SSRIs.

However, for clinical usage in the treatment of depression, these medications are taken chronically, which means that they are taken over a longer length of time. The majority of the studies that have been conducted on SSRIs to far have only looked at their use in the short term. Researchers from the University of Cambridge, working in conjunction with researchers from the University of Copenhagen, set out to find a solution to this problem. To do so, they recruited healthy volunteers, gave them escitalopram, an SSRI that is known to be one of the most well-tolerated, over the course of several weeks, and then evaluated the effect that the drug had on the volunteers’ performance on a series of cognitive tests.

There were a total of 66 participants included in the study; 32 of them were given escitalopram, while the other 34 were given a placebo. The volunteers either received the active treatment or a placebo for a period of at least 21 days, during which time they also filled out an extensive battery of self-report questionnaires and were put through a battery of cognitive function tests.

When it comes to “cold” cognition, such as attention and memory, the research team discovered that there were no significant group differences. In the majority of assessments of ‘hot’ cognition — that is, cognitive skills that engage our emotions – there were no differences found.

However, the most important discovery was that individuals who were given escitalopram showed a lower reinforcement sensitivity on two tasks when compared to those who were given placebo. Learning via feedback from our activities and the surrounding environment is an example of reinforcement learning.

The researchers employed something called a “probabilistic reversal test” in order to determine how sensitive subjects were to the effects of reinforcement. A participant in this activity would normally be presented two stimuli, denoted by the letters A and B. If they choose option A, they would get a prize four out of the five times; on the other hand, if they picked option B, they would only receive a reward once out of the five times. The rule would not be explained to the volunteers; rather, they would be required to figure it out on their own. Additionally, at some time during the experiment, the probabilities would alter, and the participants would be required to figure out the new rule.

The research team discovered that individuals receiving escitalopram had a lower likelihood of using the positive and negative feedback to steer their learning of the task when compared to those who were given a placebo. This provides evidence that the treatment altered both the subjects’ sensitivity to the incentives and their ability to react appropriately to them.

This discovery may also explain the one difference that the researchers discovered in the self-reported surveys. The team discovered that participants on escitalopram had greater difficulty attaining orgasm while having sex. This is a side effect that is often reported by patients.

The use of SSRI antidepressants is associated with the typical adverse effect of emotional numbing. They alleviate some of the mental anguish that individuals who suffer from depression experience, which suggests that this may be one of the ways in which they function. It would seem that they also diminish some of the fun that may be had. Based on the findings of the research, we can clearly understand that the reason for this is that they become less receptive to incentives, which are an essential kind of feedback.


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Anna Daniels

Anna is an avid blogger with an educational background in medicine and mental health. She is a generalist with many other interests including nutrition, women's health, astronomy and photography. In her free time from work and writing, Anna enjoys nature walks, reading, and listening to jazz and classical music.

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