Visuospatial Dysfunction in Alzheimer’s Disease Maps to a Network Centered on the Inferior Parietal Lobule

Abstract

AbstractBackgroundVisuospatial dysfunction is the predominant symptom in ∼5% of patients with Alzheimer’s disease (AD) and common in amnestic patients. If we can predict which patients are more likely to have trouble with visuospatial functioning, we can intervene earlier to prevent falls and car accidents and improve quality of life.MethodThere were 184 subjects with AD in the Alzheimer’s Disease Neuroimaging Initiative database with MRI scans and clock‐draw and clock‐copy scores ranging from 1‐5. Atrophy was defined as thinner than expected compared to age and sex matched controls. Subject network maps were generated averaging connectivity to each atrophied vertex using the normative connectome. Maps were compared to their behavioral scores generating behavior specific network maps. Atrophy networks were directly compared to a similar network generated from clock‐draw and stroke subjects.ResultAtrophy did not correlate with clock‐draw and ‐copy scores but atrophy networks identified distinct distributed brain networks. Clock‐copy scores directly correlate with atrophy connected to the bilateral angular and visuomotor gyri, which were also hubs of the network derived from stroke and clock‐draw scores.ConclusionThese results suggest that visuospatial dysfunction in AD does not occur due to atrophy in a single brain region but a distributed brain network. The concordance between atrophy in AD and stroke suggest that atrophy network mapping is a valid measure of connectivity underlying visuospatial dysfunction in AD.