MAPT and Cognitive impairment: We found disrupted connectivity (brain volume covariance networks) in groups with Alzheimer’s disease pathology (A+T−, amyloid positive, tau negative; A+T+, amyloid positive, tau positive) and other non-Alzheimer’s disease dementias (A−T−&CI, amyloid negative, tau negative, cognitive impairment), while the control group had the most connected structural network and exhibited significantly higher small-worldness compared with the A+T+ (amyloid positive, tau positive) group.