Primary Tauopathy With Logopenic/Semantic Mixed Progressive Aphasia and Frontotemporal Dementia-like Behavior

Area of Science:

• Neuroscience
• Neuropathology
• Clinical Neurology

Background:

• Alzheimer disease (AD) and frontotemporal lobar degeneration (FTLD) are distinct neurodegenerative disorders.
• Early clinical overlap between AD and FTLD can complicate diagnosis.
• Tau pathology is implicated in both AD and FTLD, but with different characteristics.

Purpose of the Study:

• To describe two cases with overlapping early clinical symptoms of AD and FTLD.
• To investigate the underlying neuropathology in these cases.
• To propose a potential new syndrome associated with non-Alzheimer tauopathy.

Main Methods:

• Case study of two individuals with complex neurological symptoms.
• Clinical assessment focusing on language and behavioral changes.
• Multimodal neuroimaging (MRI, PET) to evaluate brain structure and function.
• Pathological examination to determine underlying neuropathology.

Main Results:

• Patients exhibited phonological deficits (suggestive of AD) and semantic impairment with behavioral changes (suggestive of FTLD).
• Neuroimaging revealed primary tauopathy with 3/4-repeat tau isoforms.
• Amyloid deposition, characteristic of AD, was notably absent.

Conclusions:

• The findings suggest a previously unrecognized clinical syndrome.
• This syndrome appears associated with non-Alzheimer primary tauopathy.
• Distinguishing between AD and FTLD early on is crucial for accurate diagnosis and management.