Depression has long been a common disease, many affected people are looking for help in psychotherapy. Now a study shows: Psychotherapy not only acts on thoughts and feelings – it also changes the structure of the brain measurably, as researchers have now shown for the first time. In the case of depression, cognitive behavioral therapy increases the volume of gray brain mass in regions that are responsible for the processing of emotions. So far, such an effect was only known from antidepressants and electrostimulations.
Depression is among the most common mental illnesses: around 280 million people worldwide suffer from severe courses alone. Typically, the disease manifests itself in symptoms such as depression and lack of drive. In order to improve the life situation of those affected, they usually receive psychotherapy, often also combined with the administration of antidepressants. In severe cases, electrostimulation is sometimes used. But the causes of depression are only understood in part – also because genetic, neurophysiological, psychosocial and environmental factors interact. However, changes in the brain metabolism are concrete trigger of the symptoms. The balance of neurotransmitters such as serotonin, dopamine and noradrenaline is often disturbed in those affected.
Searching for traces in brain anatomy
A depression also leaves traces in brain anatomy. Regions that are responsible for the processing of emotions are particularly affected, including the hippocampus and the Amygdala. They usually shrink in depression. This suggests that successful treatment can also be seen in these brain regions. So far, however, it was only known that medication and electrical stimulation can increase the brain mass again in these areas. A corresponding proof of the effect of psychotherapy has so far been missing. But does this mean that conversation therapies such as cognitive behavioral therapy really have no influence on the structure of the brain?
In order to find out, researchers around Esther Zwiky from the University of Halle have now examined what 20 sessions do cognitive behavioral therapy in the brain. For this purpose, the team scanned the brains of 30 patients with severe acute depression before and after therapy with the help of structural magnetic resonance imaging. In this way, Zwiky and her colleagues were able to document changes in the shape, size and location of the gray brain mass. The brains of 30 healthy control persons who did not receive therapy were used as a comparison.
More gray cells through psychotherapy
The result: In the Amygdala and in the front right hippocampus, the volume of the gray brain mass increased significantly with depression in the course of the therapy. This fits that in 19 of the 30 patients after the therapy, some depressive complaints had improved considerably. “Above all, the increase in volume of the right amygdala was linked to an improved ability to perceive emotions,” report Zwiky and her colleagues. This so -called Alexithymia is a typical symptom of acute depression: those affected can no longer feel feelings in a normal way. Behavioral therapy relieved this – and this was also evident in the brain.
“It was already known that cognitive behavioral therapy works. Now we have a valid biomarker for the effect of psychotherapy on the brain structure for the first time,” explains senior author Ronny Redlich. The team suspects that cognitive behavioral therapies promote the formation of new neuronal connections and the adaptation of existing networks by learning new thinking patterns and training their emotional processing. In this way, the observed structural changes can contribute directly to the relief of the symptoms. In this way, conversation therapies are finally in no way inferior to other treatments such as medication and electrostimulation.
Source: Esther Zwiky (Martin Luther University Halle-Wittenberg) et al., Translational Psychiatry, DOI: 10.1038/S41398-025-03545-7
