Major Depressive Disorder (MDD) is a broad category of depression that encompasses various subtypes, including Persistent Depressive Disorder, Psychotic Depression, Postpartum Depression, Seasonal Affective Disorder, and Bipolar Disorder when depression is a part of the spectrum. Medical researchers are continually exploring new and effective ways to treat depressive disorder, recognizing the significant impact these conditions can have on individuals and their families. In their efforts, researchers are also investigating the underlying causes of depression, including the role of neural connections in the development and persistence of depressive disorders.
Decades of strengthening neuronal connections can leave the adult brain resistant to sudden change. This is particularly true in cases of treatment-resistant depression, where conventional treatments may not have the desired effect, and alternative approaches need to be considered. If the structure of our brains traps us in cycles of negative emotions and thoughts, conditions such as chronic depression can be challenging to overcome.
Thankfully, a recent study shows that with the correct treatment, some people experiencing these medical conditions could have their brains “rewired” within weeks.
Depression Treatments for People with MDD
Although not all people with MDD respond to antidepressants, electroconvulsive therapy, or cognitive-behavioral therapy (CBT), German researchers claim these treatments can alter the brain’s structure. However, at the moment, it is unknown how long those effects will last.
People with MDD frequently struggle to control their negative emotions and physiological stress responses. Under such oppressive conditions, depression symptoms can make even the most enjoyable activities in life can become onerous. Therefore, effective treatment of depression can bring about significant improvement and relief for those who are affected.
Links Between the Brain and MDD
In the past, brain imaging research studies discovered a link between severe depression and modifications in the amount of gray matter (consisting of neuron bodies) and white matter (composed of nerve fibers). In addition, increased activity in the amygdala, which affects our emotions, shrinkage in the hippocampus, which is vital for long-term memory and learning, and shrinking in the basal ganglia, which aids in processing emotions, are also linked to depression.
On the other hand, treatment-resistant MDD is characterized by alterations in the basal ganglia and the lobe responsible for processing sensory information. A comprehensive review of studies on depression can provide important insights into the various contributing factors and potential treatment options and help advance our understanding of this complex mental illness.
The diagnosis and treatment of major depression could significantly improve if there is a strong link between the function of depression and the structure of the human brain. However, many scientists disagree on whether this association is consistent or strong enough to rely on. Nevertheless, German researchers believe that it is.
Depression Treatments Increase Brain Connectivity
The latest study reveals that when antidepressant treatment was effective, some of the structural brain traits seen in MDD patients were reduced. Before starting treatment for depression, 109 MDD patients had their brains scanned with a magnetic resonance imaging (MRI) device. Patients were then treated with electroconvulsive therapy (ECT), antidepressant medication, psychological therapy, or a combination of all three treatments.
Patients’ brains were scanned again six weeks after the first MRI scan. The “before and after” results were compared to the brains of 55 healthy subjects. In the end, German researchers discovered that patients with the most dramatic reductions in depressive symptoms also exhibited the most profound changes in brain structure. After only six weeks, the connection between neurons in some areas of their brain had enhanced, regardless of treatment choice.
Jonathan Repple, a psychiatrist from the University of Frankfurt, said:
“We were surprised at the speed of response. But unfortunately, we don’t have an explanation as to how these changes take place or why they should happen with such different forms of treatment.”
Other Studies on Improving Brain Structure and MDD
Randomized controlled trials have demonstrated that CBT, ECT, and antidepressants can all dramatically reduce the symptoms of major depression; however, it is more challenging to link this improvement to effects caused by alterations in brain structure.
ECT seems to be the fastest and most effective treatment for symptoms of chronic depression, but it has the most side effects. Scientists are still working on figuring out the best treatment plan for major depression.
ECT is a form of brain stimulation that involves sending an electrical current to a patient’s brain while they are under a general anesthetic. According to mouse studies, the therapy appears to improve neuronal communication in some brain regions. Interestingly, Johns Hopkins University researchers recently discovered new brain cells forming in the hippocampus of mice treated with ECT.
The relationship between MDD and smaller hippocampal volumes has long been a topic of investigation. The majority of studies find that MDD is associated with smaller hippocampal volumes, but the direction of causality remains unclear. Reducing symptoms of depression, therefore, may have a relationship to changing the structure of the hippocampus.
Human studies have produced comparable findings. For example, ECT was found to “mould” the structure of the brain of some MDD patients in 2015, reshaping the neuronal connections in their hippocampus and amygdala.
Transcranial magnetic stimulation (TMS) has long been studied as a potential treatment option. Clinically meaningful response has been seen in 50-60% of people with depression symptoms who failed to find relief through medication. However, only around 30% experience full remission. On average, patients experience a reduction of depression symptoms for over a year after treatment ends, and some opt for additional rounds.
While CBT is linked to changed brain activation in the precuneus and prefrontal cortex, which is linked to memory and mental imagery, the effects of antidepressant medications are linked to neural plasticity in the prefrontal cortex and hippocampus.
Despite being supported by evidence, many treatments for depression do not always work equally well or produce the same levels of structural brain changes. This is because human emotions are incredibly intricate, and the brain is an extraordinarily complex organ. Even though connecting the two is very difficult, it hasn’t deterred scientists like Repple from trying.
Eric Ruhe, a psychiatrist who wasn’t involved in the study, praises Repple and his team for the complexities of their recent paper. According to Ruhe, the study must be duplicated in independent samples. Still, the findings “align very much with our current belief that the brain has much more flexibility in adaptation over (even short) time than was previously thought.”
Ruhe added:
“This means that the brain structure of patients with serious clinical depression is not as fixed as we thought, and we can improve brain structure within a short time frame, around six weeks. This gives hope to patients who believe nothing can change and have to live with a disease forever because it is ‘set in stone’ in their brain.”
The research was presented in Vienna, Austria, at the 35th annual meeting of the European College of Neuropsychopharmacology in October 2022.
