A Case of Overlap Posterior Cortical Atrophy and Logopenic Variant Primary Progressive Aphasia

Area of Science:

• Neurology
• Neurodegenerative Diseases
• Alzheimer's Pathology

Background:

• Posterior cortical atrophy (PCA) and logopenic variant primary progressive aphasia (LvPPA) are early-onset dementias typically linked to Alzheimer's disease.
• PCA involves visual processing decline, while LvPPA affects language, with both presenting earlier than typical Alzheimer's disease.
• Language deficits are common in PCA, and both conditions show parietal lobe involvement.

Observation:

• A case study of a 56-year-old man presented with overlapping anatomical, clinical, and cognitive features of PCA and LvPPA.
• Both PCA and LvPPA exhibit atrophy in temporoparietal-occipital regions, with LvPPA showing left-sided predominance.
• A defective phonological loop underlies the logopenic syndrome in both conditions, alongside other parietal deficits like dyscalculia and ideomotor apraxia.

Findings:

• The study highlights shared clinical features, etiology, and implications of the PCA-LvPPA overlap syndrome.
• A defective phonological loop is identified as a common underlying mechanism for logopenic symptoms in both PCA and LvPPA.
• The overlap syndrome may be underreported due to cases existing on a spectrum, challenging strict diagnostic criteria.

Implications:

• Recognizing the PCA-LvPPA overlap syndrome is crucial for accurate diagnosis and management of early-onset dementias.
• Understanding the shared pathophysiology, including phonological loop deficits, can inform clinical practice and therapeutic strategies.
• Further research is needed to identify and characterize the full spectrum of PCA-LvPPA overlap cases.