Does posterior cortical atrophy cause reading failure, visuospatial dysfunction, and calculation difficulty?

Posterior cortical atrophy (PCA) is a progressive neurodegenerative syndrome in which higher-order visual and other posterior-cortical functions fail early, often before prominent memory impairment. The claim is strongly supported.

Clinical and imaging pattern

• PCA shows posterior-predominant degeneration involving occipital, superior-parietal, parieto-occipital, and occipitotemporal association cortex. Longitudinal MRI demonstrates early posterior atrophy with gradual extension to other regions; medial-temporal and frontal involvement is initially less marked than in typical amnestic Alzheimer disease.
• FDG-PET commonly shows hypometabolism in posterior visual-association regions, providing functional support for the anatomical pattern.

Cognitive manifestations

• Visuospatial and visuoperceptual dysfunction are defining early features, rather than nonspecific consequences of dementia.
• Reading failure (alexia) is a recognized presentation. Compared with early-onset Alzheimer disease, PCA cohorts have shown substantially poorer reading, including line skipping, omitted words, and word misidentification—often reflecting impaired visual scanning and spatial attention rather than a primary language disorder.
• Calculation difficulty (acalculia) is also an established early feature, potentially arising from disrupted number processing, visual recognition, writing, or spatial organization. These individual symptoms vary and are not independently diagnostic.

Underlying pathology and mechanisms

• Alzheimer disease is the predominant biological cause: an autopsy meta-analysis found Alzheimer pathology in 94% of 145 PCA cases (95% CI 90–97%). In biomarker-assessed PCA cohorts, amyloid PET was positive in 94% and tau PET in 97%.
• PCA remains a clinical syndrome, not a single pathology. Lewy body disease, corticobasal degeneration, and prion disease can produce it; Lewy body co-pathology occurred with Alzheimer pathology in 44% of autopsied cases.

Bottom line

• PCA is a posterior-network neurodegenerative syndrome that commonly causes visuospatial impairment, alexia, and acalculia; Alzheimer pathology is overwhelmingly its most frequent underlying cause, although etiologic assessment should consider alternative and coexisting pathologies.