Posterior cortical atrophy: Primary occipital variant

Eur J Neurol. 2022 Jul;29(7):2138-2143. doi: 10.1111/ene.15327. Epub 2022 Mar 30.

Abstract

Background: Posterior cortical atrophy (PCA) is one of the atypical Alzheimer's disease variants, characterized by predominant visuospatial and visuoperceptual deficits, with established dorsal and ventral subtypes. A third primary occipital (caudal) variant has been suggested. We aimed to determine its demographics, clinical manifestations, and biomarker findings.

Methods: Fifty-two PCA patients were investigated. Patients underwent neuropsychological assessment, magnetic resonance imaging, and fluorodeoxyglucose (FDG)-, amyloid-, and tau-positron emission tomography (tau-PET) scans. Normalized regional FDG-PET values were represented as z-scores relative to a control population. Patients were divided into "primary occipital" and "other PCA" subgroups according to FDG-PET-defined criteria, with primary occipital defined as patients in which the z-scores for occipital subregions were at least one standard deviation lower (SD) (i.e., more abnormal) than the z-scores in all other brain regions. Global amyloid-PET, temporo-parietal FDG-PET, and temporal tau-PET regions-of-interest (ROIs) were calculated.

Results: Nine patients were classified as primary occipital; they were older (p = 0.034) and had more years of education (p = 0.007) than other PCA patients. The primary occipital group performed worse on the Ishihara test for color perception (p < 0.001), while other PCA patients performed worse on the Western Aphasia Battery (WAB) praxis scale (p = 0.005). Overall neuropsychiatric symptom burden was lower in the primary occipital group (p < 0.001). The FDG-PET meta-ROI was higher in the primary occipital subtype (p = 0.006), but no differences were observed in amyloid- and tau-PET.

Conclusions: Our findings suggest that primary occipital PCA is characterized by an older age at onset, more color perception dysfunction, less severe ideomotor apraxia, and less hypometabolism in temporo-parietal meta-ROI compared to established phenotypes.

Keywords: Alzheimer's disease; posterior cortical atrophy; visuospatial impairment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease* / pathology
  • Atrophy / pathology
  • Brain / pathology
  • Fluorodeoxyglucose F18*
  • Humans
  • Magnetic Resonance Imaging
  • Positron-Emission Tomography / methods

Substances

  • Fluorodeoxyglucose F18