Depression patients have a brain network twice the normal size
A recent study has revealed that individuals suffering from depression possess a brain network, known as the frontostriatal salience network, which is nearly double its usual size. This discovery was made by researchers from Weill Cornell Medicine in New York City. The team's findings were published in the journal Nature. The frontostriatal salience network is associated with reward processing and filtering external stimuli, although its complete functions remain unclear.
Intruding on space usually occupied by other functional networks
The research team found that the frontostriatal salience network is expanded nearly twofold in the cortex of most individuals with depression. This effect was replicable in several samples and caused primarily by network border shifts, with three distinct modes of encroachment occurring in different individuals. The study suggests that this particular brain network can intrude on space usually occupied by other functional networks.
Advanced mapping technique used in research
The study is significant for its use of precision functional mapping, a relatively new approach that provides researchers with a more detailed view of each individual brain and its layout. An initial analysis of brain scans from 57 individuals, compared to 37 healthy controls, identified the frontostriatal salience network expansion. These results were then backed up by comparisons with larger datasets.
Network expansion observed in children prior to depression onset
Further tests on a smaller group over 18 months, as well as brain image data from 114 children collected before and after a depression diagnosis, also showed results similar to those from the original group. "Salience network expansion was stable over time, unaffected by mood state, and detectable in children before the onset of depression later in adolescence," researchers wrote. This suggests that it's a risk factor and possible contributor to depression, rather than something that happens because of it.
Need for further research to understand depression link
The researchers emphasize that more data from larger and diverse groups of individuals, collected over longer periods, will be needed to fully understand the link between this specific brain network and depression. "These findings identify a trait-like brain network topology that may confer risk for depression and mood-state-dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time," wrote the researchers.
