Clinical Implications of Amyloid-Beta Accumulation in Occipital Lobes in Alzheimer's Continuum

Abstract

A substantial amount of amyloid-beta (A beta) accumulates in the occipital cortices; however, it draws less attention. We investigated the clinical implications of A beta accumulation in the occipital lobes in the Alzheimer's disease (AD) continuum. [18F]-Florbetaben amyloid PET scans were performed in a total of 121 AD or amnestic mild cognitive impairment (aMCI) patients. Of the 121 patients, 74 A beta positive patients were divided into occipital A beta positive (OCC+) and occipital A beta negative (OCC-) groups based on A beta accumulation in the bilateral occipital lobes. The OCC+ group (41/74, 55.4%) was younger and had a younger age at onset than the OCC- group. The OCC+ group also had an increased standard uptake value ratio in the occipital lobes and greater cortical thinning in relevant areas. The OCC+ group had a higher global deterioration scale, lower performance for the copy, immediate recall, delayed recall, and recognition in Rey-Osterrieth Complex Figure tests than the OCC- group, although both groups had similar disease durations. AD or aMCI patients in the OCC+ group exhibited features noted in early onset AD with relevant neuropsychological and image findings. Occipital A beta positivity in amyloid PET scans need to be considered as an underestimated marker of early onset AD continuum.