How gratitude changes our brain

Many studies of the last 10 years indicate the benefits of gratitude: when people consciously recall the good in their life, they become happier. But we could not rely on the results of the experiments. Most of them conducted on well-off people. We decided to find out if gratitude helps people with psychological problems.

In our study, 300 people took part, most of them were students who faced psychological problems and enrolled in psychotherapy sessions. Our experiment started before the beginning of their therapeutic sessions: many participants suffered from a depressive or anxious disorder and on average showed low rates of psychological health.

We randomly divided people into three groups, participants of each of them went to the sessions to the therapist. The difference was in the additional task. The participants of the first group once a week wrote a letter of gratitude to some person. Participants of the second described their thoughts and feelings caused by unpleasant situations in their lives. Participants of the third group did not write anything. The experiment lasted three weeks.

A few weeks after the end of the experiment, we assessed the psychological health of the participants. In the first group, it significantly improved, in the other two there were no changes. Hence, gratitude helps not only healthy, but also that it struggles with psychological problems. We carefully analyzed the research data to understand how gratitude affects the brain and the body.


 How gratitude changes our brain

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We compared the share of words with positive and negative emotional assessment, which were used in the texts of participants of two writing groups. Participants who wrote letters of gratitude used more positively colored words and fewer words with negative emotional coloring compared to the second group. However, positive words do not yet guarantee mental well-being. Only those people who used less negative words, subsequently improved their condition. The absence of negative statements led to a difference in the state of mind between the two groups.

A letter of gratitude switches attention from negative emotions, like resentment and envy. When you write, how grateful people are and how much good people have brought to life, it is difficult to get stuck in thoughts about bad events.


We told the participants who wrote letters of gratitude that it is not necessary to send letters to the addressees. Only 23% of the participants actually sent letters. But all the other members of the group also corrected their condition, although the letters remained with them. So the actual transfer of gratitude does not play a key role.

Let’s say you want to write a letter to someone gratefully, but do not dare. Write it anyway. Then decide whether to send or not. The act of writing a letter in itself will help assess people in your life and shift the focus of attention from negative thoughts and experiences.

The positive effect of letters of gratitude does not arise instantly. In our study, it accumulated over time. A week after the end of the written practices, we did not notice the difference in the state of mind between the participants of the three groups.

However, four weeks later, the first group that wrote letters of gratitude showed an improvement over the other two groups. After 12 weeks after the end of the experiment, the difference became even more noticeable.

In many other similar studies, the positive effect decreased over time. In our case, the opposite happened. Perhaps the participants discussed their letters. These discussions intensified the psychological effects of writing letters.

If you are writing a thank you letter, do not expect immediate improvement. Be patient. Gratitude needs time to act.


Three months after the beginning of the psychotherapeutic session, we compared several people who wrote letters of gratitude, with those who did not write anything. We wanted to find out if their brains started to process information in a different way.

To do this, they were asked to perform an exercise “pay another” and in the process used a tomography to evaluate the brain activity of participants. During the exercise, the “benefactor” gives each participant a small amount of money and asks him to transfer it to another person if he feels gratitude. Then the participants decide whether to transfer money for a good cause, and determine the amount.

We wanted to separate the donations, motivated by a sense of gratitude, from donations based on other feelings, for example, debt or guilt. To this end, participants were asked to note how grateful they were to the benefactor, how much they wanted to participate in charity, and how much they felt guilty if they did not do so. The participants also filled in the questionnaires, which allowed to determine how grateful they are in general in life.

Letter of gratitude

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People who were generally grateful gave more money for a good cause and showed higher neural sensitivity in the medial prefrontal cortex. This zone is responsible for learning and making decisions. It can be assumed that more grateful people care more about how to express their gratitude.
We also compared the brain activity of participants who wrote letters of gratitude, with indicators of those who did not, and noticed the difference. Those who wrote letters of gratitude had more noticeable activity in the medial prefrontal cortex.

We found this effect three months after the start of the experiment. This means that the expression of gratitude has a long-term effect: constant practice trains the brain, and it becomes more sensitive to the experience of gratitude in the future. In the long term, it strengthens mental health.

It does not matter if you are facing a psychological problem, try writing a letter of thanks. Most of the time and energy we spend on the pursuit of what we do not have. Gratitude helps us to appreciate people next to us and things that we already have.

About the authors
Joshua Brown (psychologist, works at the Indian University).
Joel Wong (psychologist, works at the Indian University).

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