What is the relationship between depression and the brain's reward system?

A depression is a psychiatric illness that makes its victims have the affected emotional, thus living with constant feelings of discouragement. Because of this, the region responsible for transmitting wills and making decisions, known as the brain reward system, becomes compromised. That is, the ability to feel pleasure and satisfaction is also reduced, as it is directly linked to this system. Check out the study that proved this relationship now.

The relationship between depression and the brain's reward system

A patient diagnosed with depression loses interest in carrying out routine activities, as he no longer feels satisfaction in almost anything else. With this, it is possible to develop anhedonia, a condition that makes it impossible to feel pleasure. In fact, anhedonia occurs in 37% of people who suffer from depression, a situation that has strong indications of being linked to the reward system of the brain. Since then, many studies have been carried out to prove this link, but not all answers have been clarified. However, researcher Hanneke Geugies conducted a study that compared the brain activations of a group of people with anhedonia with those of another healthy group. Check out how this study was carried out:

Participants and their characteristics

Those selected were 24 adults diagnosed with at least mild depression. The comparison was made with another group with the same number of people and with the same sex. Furthermore, participants in both groups had no history of chemical dependency or neurological problems. Furthermore, they all spoke Dutch fluently and had no health problems that would impede the MRI process.

Process

While undergoing the MRI, the participants had to complete four cognitive tasks that rewarded them financially. By sequence, reward gain, neutrality and loss indicators were presented; a target blue square and, finally, the balance of rewards for each completed activity. With this, the balance and indicators were visible for 1.5 seconds, while the target remained for only 0.5 seconds.

The initial value of the participation was fixed at 10 euros, which would later be added to the rewards earned during the tasks.

Result

From there, two moments were observed: when the participants saw the initial reward and when they received the final result. Consequently, the group of people with depression had reduced brain activity when compared to the healthy group. Even those who had anhedonia also had their brain activity lower than “expected”.

Because of this, the researchers responsible for the study concluded that the inability to feel pleasure occurs when brain reward system connectivity is altered, as well as because of activation deficiencies isolated.