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Two distinct subtypes of right temporal variant frontotemporal dementia
K A Josephs1, J L Whitwell, D S Knopman
1Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA. josephs.keith@mayo.edu
Neurology
|November 4, 2009
Summary
Right temporal frontotemporal dementia (FTD) is not a single entity. This study identified two subtypes, differentiating between tau and TDP-43 protein pathologies, crucial for understanding FTD progression.
Area of Science:
- Neuroscience
- Neuropathology
- Clinical Neurology
Background:
- Right temporal frontotemporal dementia (FTD) presents with distinct behavioral and cognitive symptoms.
- The homogeneity of right temporal FTD as a clinical, imaging, and pathological entity was previously unclear.
Purpose of the Study:
- To investigate whether right temporal FTD represents a homogeneous entity.
- To differentiate subtypes of right temporal FTD based on clinical, imaging, and pathological features.
Main Methods:
- 101 FTD subjects were analyzed using atlas-based parcellation for grey matter volumes.
- Voxel-based morphometry assessed grey matter loss in right temporal FTD subtypes.
- Clinical, neuropsychological, genetic, and neuropathologic data were reviewed.
Main Results:
- 20 subjects with right temporal FTD were identified, classified as behavioral variant FTD (bvFTD) or semantic dementia (SMD).
- bvFTD subjects exhibited more frontal lobe atrophy and behavioral changes, while SMD subjects showed greater fusiform atrophy and specific cognitive deficits.
- Pathological analysis revealed tau protein abnormalities in bvFTD and TDP-43 abnormalities in SMD.
Conclusions:
- Right temporal FTD comprises at least two distinct subtypes.
- These subtypes correlate with underlying tau or TDP-43 protein pathologies.
- This differentiation aids in understanding FTD subtypes and their associated pathologies.
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