Degradation in intrinsic connectivity networks across the Alzheimer's disease spectrum

IntroductionChanges in intrinsic functional connectivity (iFC) have been reported at various stages of the Alzheimer's disease (AD) spectrum. We aimed to investigate such alterations over a variety of large-scale intrinsic brain networks (iBNs) across the spectrum of amyloid β positivity and uncover their relation to cognitive impairment.MethodsEight iBNs were defined from resting-state functional magnetic resonance imaging data. In amyloid β-positive healthy subjects, prodromal, and AD patients (N = 70), within-network iFC (intra-iFC) and between-network iFC (inter-iFC) were correlated with scores of cognitive impairment.ResultsAcross all iBNs, a general degradation in intra-iFC along the scale of cognitive impairment severity was found. Only subtle changes in inter-iFC were identified.DiscussionAcross the AD spectrum, changes in iFC that are strongly related to cognitive impairment occur within an extensive variety of networks