Default mode network anti-correlation as a transdiagnostic biomarker of cognitive function

The default mode network (DMN) is intricately linked with processes such as self-referential thinking, episodic memory recall, self-projection, and understanding the mindset of others. Over recent years, there has been a surge in examining its functional connectivity, particularly its antagonistic relationship with frontoparietal networks (FPN) involved in top-down attention, executive function, and cognitive control. Notably, the DMN demonstrates an anti-correlated connection with FPN and Dorsal Attention Network (DAN), leading to its deactivation when one's attention is turned towards the external environment. The fluidity in switching between these internal and external modes of processing—highlighted by this anti-correlated functional connectivity—has been proposed as an indicator of cognitive health and mediated by salience networks (SAL). Due to the ease of the estimation of functional connectivity-based measures through resting state fMRI paradigms, there is now a wealth of large-scale datasets, paving the way for standardized connectivity benchmarks. This review delves into the promising role of DMN connectivity metrics as potential biomarkers of cognitive state across attention, mind wandering and meditation states, and investigating deviations in clinical conditions such as anxiety, depression, ADHD, PTSD and others. Additionally, we tackle the issue of reliability of network estimation and functional connectivity and share recommendations for using connectivity measures as a biomarker of cognitive health.