Dementia study finds both decreased and increased brain connectivity

A new study published on arXiv by researchers Hegedus, Mora, Varga, and Grolmusz examines structural connectivity changes in the human brain during dementia and aging. Leveraging the extensive OASIS-3 neuroimaging dataset, the team mapped small gray matter regions to identify localized differences in connectivity. As anticipated, they observed decreased connectivity in key memory regions—the hippocampus and temporal lobe—aligning with known cognitive decline patterns in dementia. These areas are critical for episodic memory and language processing, so their reduced connectivity helps explain common symptoms.

More surprisingly, the analysis revealed increased connectivity in several regions: the precuneus, cuneus, and insula. This counterintuitive finding suggests that dementia may involve not only degradation but also compensatory reorganization or aberrant hyperconnectivity. The precuneus is involved in self-consciousness and visuospatial processing, while the insula plays a role in emotion and interoception. These results could point to new biomarkers or targets for intervention, though the functional implications of increased connectivity remain to be fully understood. The study underscores that dementia's effects on brain networks are more complex than simple widespread loss of connectivity.