Brain Connectivity Reveals Two Distinct Flavours of Depression

Major depressive disorder (MDD) is famously complex, with treatments working differently for different people. New research provides a potential reason why, identifying two distinct subtypes of the disorder based on the brain's internal communication patterns.

By analysing the functional connectivity—essentially, how different brain regions 'talk' to each other—in over 800 patients, scientists found two robust groups. The 'hypoconnectivity' subtype showed weaker-than-usual communication, while the 'hyperconnectivity' subtype displayed excessively strong links, with alterations centred in the brain's default mode network.

These two profiles are more than just wiring diagrams; they have distinct biological roots. While both share links to serotonin systems, the hypoconnectivity group was associated with genes for glial support cells and neurotransmitters like GABA. In contrast, the hyperconnectivity group was linked to genes for neuronal development and neurotransmitters like glutamate and norepinephrine. This subtyping could pave the way for more personalised treatment organisation.