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Primary motor cortex involvement in Alzheimer disease.
1University Institute of Pathology, CHUV, Lausanne, Switzerland.
Journal of Neuropathology and Experimental Neurology
|November 24, 1999
Summary
Alzheimer disease (AD) significantly impacts the primary motor cortex, not just memory areas. This study found neurofibrillary tangles in motor regions, suggesting motor dysfunction in late-stage AD.
Area of Science:
- Neuropathology
- Neurodegenerative Diseases
Background:
- Alzheimer disease (AD) pathology is well-documented in the entorhinal cortex, hippocampus, and associative cortical areas.
- Contradictory findings exist regarding the primary motor cortex's involvement in AD.
Purpose of the Study:
- To investigate the involvement of the primary motor cortex in Alzheimer disease.
- To compare the distribution of senile plaques (SPs) and neurofibrillary tangles (NFTs) in the primary motor cortex versus other cortical areas.
Main Methods:
- Autopsy brains from 29 cases (17 AD, 7 mild AD-type changes, 5 controls) were analyzed.
- Morphometric analysis of SPs (beta-amyloid-immunostained sections) and quantitative analysis of NFTs (Gallyas-stained sections) were performed.
- Five cortical areas were examined, including the primary motor cortex.
Main Results:
- SPs occupied a similar cortical surface percentage across all analyzed areas (e.g., 15.8% in primary motor cortex).
- NFTs were significantly more abundant in the entorhinal cortex (41 per 0.4 mm²) compared to other areas, including the primary motor cortex (11.5 per 0.4 mm²).
Conclusions:
- The primary motor cortex shows significant involvement in Alzheimer disease.
- The presence of NFTs in the primary motor cortex suggests potential motor dysfunction in the late and terminal stages of AD.