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An anatomic substrate for visual disconnection in Alzheimer's disease
J H Morrison1, P R Hof, C Bouras
1Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, New York 10029.
Annals of the New York Academy of Sciences
|January 1, 1991
Summary
Some Alzheimer's disease (AD) patients show early visual symptoms due to distinct brain lesion patterns. This study found increased damage in visual areas and less in the prefrontal cortex in these specific AD cases.
Area of Science:
- Neuropathology
- Neuroscience
- Ophthalmology
Background:
- Alzheimer's disease (AD) typically damages association areas more than primary sensory cortices.
- Standard AD neuropathology involves neurofibrillary tangles and neuritic plaques.
- Visual symptoms are not commonly the initial presentation of AD.
Purpose of the Study:
- To investigate neuropathologic differences in Alzheimer's disease patients with prominent early visual symptoms.
- To identify if a distinct pattern of brain lesions correlates with initial visual deficits in AD.
- To understand the relationship between specific corticocortical pathway disruption and AD symptomatology.
Main Methods:
- Clinical and neuropathologic evaluation of autopsy brain samples from a large patient cohort.
- Quantitative analysis of lesion distribution (neurofibrillary tangles and neuritic plaques) in specific brain regions.
- Comparison of pathologic profiles between AD patients with and without prominent visual symptomatology.
Main Results:
- A subset of AD patients presented with visual symptoms as the primary early sign.
- These patients exhibited increased lesions in primary and association visual areas.
- Conversely, these cases showed fewer lesions in the prefrontal cortex compared to typical AD.
- Disruption of specific visual association pathways was observed, which are usually less affected in AD.
Conclusions:
- The distribution of neuropathologic markers in AD can vary, leading to different clinical presentations.
- Selective loss of specific corticocortical systems, particularly visual pathways, may cause prominent early visual symptoms in some AD cases.
- This suggests that AD's clinical and neurologic manifestations can be linked to differential neuropathologic patterns.