Depression in Multiple Sclerosis Linked to Brain Inflammation

Researchers target causes of severe depression in MS patients.

Brain inflammation found in a certain region of the brain was linked with depression in multiple sclerosis (MS) patients during a recent study.

Hippocampus is a region of the brain implicated in the genesis and maintenance of depression, and in the pathology of MS. In a new study, researchers sought to examine the relationship between hippocampal immune response, functional connections, and depressive symptoms.

To achieve this, researchers combined 2 complementary brain imaging techniques, called positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), to examine 13 MS patients and 22 healthy controls. The PET was used for the quantification of activated microglia, a measure of immune response, while the fMRI was used to assess the strength of hippocampal connections to an extensive network of brain regions involved in emotion.

With the PET imaging, the results of the study showed that there was immune activation in the hippocampus of MS patients.

“We also discovered that more inflammation was associated to more severe symptoms of depression,” said first study author Alessandro Colasanti.

The fMRI showed that during rest the immune activation in the hippocampus altered its connections with other brain regions.

“This study, combining 2 advanced complementary brain imaging methods, suggests that the inflammation of the hippocampus affects the brain function and causes depression,” Colasanti.

The findings suggest that inflammation in the hippocampal could be the contributing cause of high rates of depression in MS patients.

“This study elegantly links hippocampal inflammation to depression,” said Dr. John Krystal, editor of Biological Psychiatry.

The authors noted that they predict an effective and targeted treatment of brain inflammation could help properly restore brain function, while protecting against depression in MS patients.