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

INTRODUCTION: Changes 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.

METHODS: Eight 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.

RESULTS: Across 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.

DISCUSSION: Across the AD spectrum, changes in iFC that are strongly related to cognitive impairment occur within an extensive variety of networks.