Part of Brain Network Much Bigger In People With Depression, Scientists Find

Researchers have discovered that people with depression have an expanded brain network, specifically the frontostriatal salience network, which is 73% larger compared to healthy individuals. 'It's taking up more real estate on the brain surface than we see is typical in healthy controls,' said Dr Charles Lynch, a co-author of the research, from Weill Cornell Medicine in New York. He added that expansion meant the size of other -- often neighboring -- brain networks were smaller. The Guardian reports: Writing in the journal Nature, Lynch and colleagues report how they used precision functional mapping, a new approach to brain imaging that analyses a host of fMRI (functional MRI) scans from each individual. The team applied this method to 141 people with depression and 37 people without it, enabling them to measure accurately the size of each participant's brain networks. They then took the average size for each group. They found that a part of the brain called the frontostriatal salience network was expanded by 73% on average in participants with depression compared with healthy controls.

These findings were supported by an analysis of single brain scans previously collected from 932 healthy people and 299 with depression. The team said the size of this brain network in people with depression did not change with time, mood or transcranial magnetic stimulation treatment. However, brain signals between different parts of the network became less synchronised when participants had certain symptoms of depression, with these changes also associated with the severity of future symptoms. The team added that an analysis of brain scans from 57 children who went on to develop depression as adolescents revealed this brain network was expanded years before their symptoms developed, while it was also expanded in adults with late onset depression.

The researchers said this suggested an expanded brain network could be a risk factor for developing depression, rather than a consequence of the condition. However, they said it was unclear to what extent this enlarged network was the result of genetics or experiences, and whether the association with depression arose from this expansion or from other brain networks consequently being smaller. The team added that their results could offer a way to explore whether certain people may be at increased risk of developing depression, and could help develop personalised treatments.

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