Treating depression changes the structure of the brain, scientists find

Decades of strengthening neural connections can make the adult brain stubbornly resistant to rapid change. Should the structure of our brain keep us locked in cycles of dark moods and thoughts, disorders like Chronic depression can be extremely difficult to shake.

The brains of some patients with major depressive disorder (MDD) can be “rewired” within weeks if given the right treatment, new research finds.

Antidepressants, behavioral therapy, and electroconvulsive therapy don’t work for everyone with MDD, but scientists in Germany claim these treatments have the power to alter brain structures. How long these changes will take remains to be seen.

People with MDD often have trouble regulating negative emotions and their physiological responses to stress. Under such difficult conditions, enjoying even the most pleasurable activities in life can feel stressful.

Historically, brain imaging studies have found that major depression is associated with changes in the volume of gray matter (made up of neuron bodies) and white matter (made up of nerve fibers). It’s also associated with an increase in amygdala activity, which affects emotional experiences; shrinkage of the hippocampus, which plays an important role in long-term learning and memory; and shrinkage of the basal ganglia, which helps process emotions.

Treatment-resistant MDD, on the other hand, is characterized by changes in the basal ganglia and the lobe that processes sensory information.

If there really is a strong connection between the structure of a human brain and the function of depression, it could seriously help improve diagnosis and treatment.

Today, however, researchers disagree on whether this connection is consistent or robust enough to rely on.

Researchers in Germany assume so.

Their new study was presented at the 35th European College of Neuropsychopharmacology in Vienna. The results suggest that some of the structural brain features found in MDD patients were alleviated when antidepressant treatment was successful.

Before treatment for depression, the brains of 109 patients with MDD were scanned with a magnetic resonance imaging (MRI) scanner. Then the patients were treated with either electroconvulsive therapy, psychological therapy, or antidepressants, or a combination of all therapies.

Six weeks after the initial MRI scan, the patients’ brains were scanned again. The before-and-after results were then compared to the brains of 55 healthy participants.

Ultimately, the authors found that patients with the greatest symptom improvements also had the most structural brain changes. After six weeks, connectivity between neurons in certain parts of their brains had increased, and these effects were independent of the choice of treatment.

“We were surprised by the speed of reaction,” says psychiatrist Jonathan Repple from the University of Frankfurt.

“We have no explanation for how these changes occur or why they should occur with such different forms of treatment.”

Randomized controlled trials have shown that electroconvulsive therapy, cognitive behavioral therapy, and antidepressants can all significantly improve depressive symptoms, but it is much more difficult to link this improvement to structural changes in the brain.

ECT appears to be the most effective and fastest treatment of the bunch, although it comes with more side effects and scientists are still trying to figure out the most successful regime.

ECT works by passing an electrical current through a patient’s brain while they’re under general anesthesia, and in mouse studies, the therapy appears to improve communication between neurons in certain parts of the brain. In fact, researchers at Johns Hopkins University recently found new brain cells developing in the hippocampus of ECT-treated mice.

Human studies have found similar results. For example, in 2015, ECT was found to “shape” the brain structures of some MDD patients, reshaping the neural connections in their amygdala and hippocampus.

Antidepressants, on the other hand, are associated with neural plasticity in the hippocampus and prefrontal cortex, and CBT is associated with altered brain activation in the prefrontal cortex and precuneus that is linked to mental imagery and memory.

Although these depression treatments are evidence-based, they are not always equally effective, nor do they result in consistent structural changes in the brain.

The brain is an incredibly complex structure, and human emotions are damn complicated themselves. Putting the two together is incredibly challenging work, but that hasn’t stopped scientists like Repple from trying.

Psychiatrist Eric Ruhe, who was not involved in the current study, commends Repple and his colleagues for the difficulty of their recent work.

He says the study has yet to be replicated in independent samples, but that the results “are in very good agreement with our current belief that the brain has much more flexibility in adapting over (even short) time periods than previously thought.”

“This means that the brain structure of patients with major clinical depression is not as solid as we thought, and we can improve the brain structure in a short time frame of about 6 weeks,” explains Ruhe.

“This gives hope to patients who believe that nothing can change and that they will have to live with a disease forever because it is ‘set in stone’ in their brain.”

The work was presented at the 35th European College of Neuropsychopharmacology in Vienna.