Childhood injuries and the brain: scientists have uncovered the mechanism of motivation loss

Psychologists and psychiatrists have long known that severe events in childhood increase the risk of depression, anxiety disorders and other mental illnesses in adulthood. However, until now, it was not fully understood exactly what changes occur in the brain and why the consequences may appear years later. A new study by scientists has shown that childhood traumas can change the functioning of the reward system, a network of brain structures responsible for motivation, pleasure, and the pursuit of goals. According to the authors, it is these changes that can make a person more vulnerable to apathy and other mental disorders. For more information, see the Izvestia article.

How childhood injuries are related to changes in the brain's reward system

The study was conducted by an international group of scientists, the results of which were published in The journal of Neuroscience. The authors set themselves the task of understanding how difficult experiences in childhood can affect brain function even before the onset of mental illness.

To do this, the researchers analyzed data from young people who had traumatic childhood events assessed, had magnetic resonance imaging of the brain performed, and studied behavioral patterns. Scientists have paid special attention to the so—called reward system, a network of brain regions that helps people experience pleasure, stay motivated, and make decisions.

The researchers found the most noticeable changes in the interaction of the hippocampus, a structure responsible for memory and emotion processing, with the nucleus accumbens, which is considered one of the key centers of the reward system. It was this connection that was weakened in the participants who reported more difficult childhood experiences.

According to the authors, such changes in themselves do not mean that a person will necessarily develop a mental disorder. However, they can become a kind of biological vulnerability factor: with additional stress, the likelihood of developing apathy, depression, or other disorders may be higher.

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To understand the significance of the discovery, it is important to understand how the brain's reward system works. It helps a person to experience pleasure from achievements, receive positive emotions from communication, learning or creativity and maintain the desire to act further. When this system is functioning normally, the brain associates certain actions with a sense of reward, maintaining motivation.

If the interaction between the structures of the system is disrupted, it becomes more difficult for a person to feel satisfaction even from events that previously brought joy. In psychiatry, this condition is called anhedonia, a decrease in the ability to experience pleasure. It is anhedonia and marked apathy that are considered to be among the most characteristic symptoms of depression, schizophrenia and a number of other mental disorders.

Researchers suggest that childhood injuries do not destroy the brain directly, but gradually change the functioning of neural networks responsible for emotions, memory and motivation. Therefore, the consequences can appear much later — sometimes decades after the events experienced. The authors of the new work believe that it is the disruption of the connection between the hippocampus and the reward system that may explain why some people remain psychologically stable after a difficult childhood, while others are more susceptible to the development of mental illness.

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The authors of the study emphasize that the results obtained do not mean the inevitable development of mental illness in every person who has experienced a difficult childhood. It's just about increased vulnerability, not predestination. This is largely due to the plasticity of the brain — its ability to change throughout life. Modern research shows that new neural connections can form even in adulthood, which means that brain function is not unchanged.

According to other studies, psychotherapy, regular physical activity, adequate sleep, and strong social support can have a positive effect. All these factors can change the activity of neural networks associated with emotion processing and stress, reducing the risk of developing mental disorders.

The authors of the new work hope that understanding the biological mechanisms underlying the effects of childhood trauma will allow doctors to identify people at risk earlier and develop more accurate prevention methods. Instead of treating an already developed disease, specialists will be able to intervene much earlier — even at a stage when changes exist only in the brain and have not yet manifested themselves in clinical symptoms.