Scientists discover the structure of the adult brain

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image: Representative map of affected connections in the brain. The number of these connections increased after treatment.
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Credit: Jonathan Repple

Scientists believe that the structure of the adult brain is generally rigid and incapable of rapid change; now new work has shown that’s not true. German researchers have shown that hospital treatment of depression can lead to an increase in brain connectivity, and patients who respond well to this treatment show a greater increase in connectivity than those who do not.

Presenting the work at the European College of Neuropsychopharmacology Congress in Vienna, lead researcher Professor Jonathan Repple said:

Commenting, Dr Eric Ruhe, of Rabdoud University Medical Center, Nijmegen, the Netherlands, said:

This means that the brain structure of patients with severe clinical depression is not as fixed as we thought, and we can improve the brain structure in a short time, about 6 weeks. We have found that while this treatment leads to an increase in brain connectivity, it is also effective in combating the symptoms of depression. This gives hope to patients who believe that nothing can change and that they must live with a disease forever, because it is “carved in stone” in their brain”.

The researchers, working at the University of Münster in Germany, studied 109 patients with severe depression (major depressive disorder) and compared them to 55 healthy controls. Their brains were scanned using an MRI scanner that had been set up to identify which parts of the brain were communicating with other parts, determining the level of connections in the brain. Patients were then treated for depression, some with electroconvulsive therapy (ECT), some with psychological therapy or medication, some with a combination of all therapies. After processing, they were then rescanned and the number of connections was recounted. They were also retested for symptoms of depression.

Professor Repple (now professor of predictive psychiatry at the University of Frankfurt) said:

We found that treating depression changed the infrastructure of the brain, which goes against previous expectations. The treated patients showed a greater number of connections than they had shown before the treatment. Moreover, those who showed the most response to treatment had developed a greater number of new connections than those who showed little response. A the second analysis showing that there are no temporal effects in healthy controls confirms our conclusions that we are seeing something that is related to the disease and, more importantly, to the treatment of that disease.

We found that these changes happened over a period of only about 6 weeks, we were surprised at how fast the response was. We have no explanation as to how these changes occur, or why they should occur with such different forms of treatment.”

“This is a very interesting and challenging study in which the authors repeated MRI scans to reveal changes in structural connectivity over time in patients treated for depression.

The results are very much in line with our current belief that the brain has much more flexibility to adapt over (however short) a period of time than previously thought. Indeed, a major insight into what the treatment of depression (and other psychiatric illnesses) invokes is plastic changes over time. This has been proposed as a common mechanism for antidepressants, psychotherapy, and electroconvulsive therapy. However, the amount of research to elucidate which changes are necessary or specific for treatment response or depression remission is limited. Additionally, the next question is whether different treatments have the ability to specifically alter targeted brain networks or vice versa whether we can use brain network disturbances as measured in the present study to choose which therapy will be helpful.

The fact that the changes observed over time cannot be associated with any form of treatment is unfortunate, but as the authors themselves suggest a topic for further research. First, these results should be replicated in independent samples, which hopefully will happen soon. Second, further elaboration of this approach would be daunting and should be strongly supported as this work could help bridge the current gap between neuroscience and evidence-based patient care.”

This is an independent comment, Dr. Ruhe was not involved in this study.

This work is presented at the 35e European College of Neuropsychopharmacology Annual Conference, taking place in Vienna and online October 15-18, see https://www.ecnp.eu/Congress2022/ECNPcongress. Up to 5000 delegates are expected. ECNP is the leading European organization working in the field of applied neuroscience.


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