Brain inflammation may lead to depression in MS patients

Patients suffering with multiple sclerosis (MS) have higher rates of depression than the general population, as a result of inflammation in a brain region, finds a study.

MS is a progressive neurological disorder, which attacks the spinal cord and brain as well as can lead to disability and death.

The findings suggested that depression in MS patients was found associated more generally with elevated inflammatory markers and hippocampal pathology, the researchers said. 

An inflammation of the hippocampus, a region of the brain implicated in the genesis and maintenance of depression was found to alter its function and contribute to the symptoms of depression.

"We also discovered that more inflammation was associated to more severe symptoms of depression," said lead author Alessandro Colasanti from King's College london.

To evaluate pathophysiologic mechanisms, the team explored the relationships between hippocampal neuroinflammation, depressive symptoms and hippocampal functional connectivities defined by resting-state functional magnetic resonance imaging (fMRI) in 13 patients with MS and 22 healthy control subjects.

Positron emission tomography (PET) imaging revealed immune activation in the hippocampus of patients with multiple sclerosis. 

"This study, combining two advanced complementary brain imaging methods, suggests that the inflammation of the hippocampus affects the brain function and causes depression," Colasanti added.

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

An effective and targeted treatment of brain inflammation would help to restore brain function and protect against depression in MS, the authors suggested in the study appearing in the journal Biological Psychiatry.