Researchers identify brain changes underlying different types of depression

Researchers at QIMR Berghofer Medical Research Institute have used brain imaging technology to identify distinct changes that occur in the brains of people with different sub-types of major depressive disorder (MDD). The findings will in future help the researchers to develop a diagnostic test for different types of depression.

The study was led by Dr Christine Guo, the head of the Translational Neuroscience laboratory at QIMR Berghofer, and also involved researchers from the University of New South Wales and the Black Dog Institute. The findings have been published in the journal Psychological Medicine.

At least one in five Australians will be affected by MDD at some time in their lives. MDD is a heterogeneous clinical condition, meaning it can come in different forms. “Melancholia” is a long-standing proposed sub-type of MDD, but as yet, there is no clear neurobiology-based diagnostic test to detect it.

“The underlying changes that occur in the brain can be quite different in patients with different types of depression,” Dr Guo said.

“This means that patients with different types of depression require, and will respond to, different kinds of treatment.

“The problem for doctors though, is that these patients can present with overlapping symptoms including sad mood, low energy and poor sleep. This means that it can be very difficult to accurately diagnose patients with a particular type of depression and to prescribe the most effective treatment.”

Dr Guo and her colleagues conducted MRI scans on the brains of two groups of patients who were diagnosed at a specialist clinic with either melancholia or non-melancholic depression.

The researchers observed the neuro-biological changes that occurred in different parts of the patients’ brains as they watched happy and sad movies.

“We were able to see two distinct sets of changes happening in the brains of the two groups of patients,” Dr Guo said.

“By identifying the distinct neurobiological changes that are associated with different types of depression, we hope that we will in future be able to use MRI scans to accurately diagnose patients so they can receive the most appropriate treatment.”

The researchers also observed the changes that occurred in a particular part of the brain, known as the subgenual ACC, which has been the target of a previous clinical trial.

“Researchers in the United States tried implanting electrodes and stimulating this part of the brain. It was a very promising trial, but it ultimately failed,” Dr Guo said.

“We found that the two groups of patients we observed showed opposite changes in this region of the brain.

“This finding suggests that stimulating this part of the brain could potentially work in some patients but not others.

“We think that in future we may be able to use brain imaging to identify which patients are good candidates for brain stimulation.”

The study was funded by the National Health and Medical Research Council (NHMRC) and Queensland Health.