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Alzheimer disease without neocortical neurofibrillary tangles: "a second look"
P Tiraboschi1, M N Sabbagh, L A Hansen
1Dipartimento di Scienze Neurologiche, Ospedale Niguarda Ca' Granda, Milan, Italy.
Neurology
|April 14, 2004
Summary
Alzheimer disease can present similarly with or without neurofibrillary tangles (NFTs). Patients without neocortical NFTs may have slower cognitive decline and subtle tau pathology contributing to dementia.
Area of Science:
- Neuropathology
- Neurodegenerative Diseases
- Alzheimer's Disease Research
Background:
- Alzheimer disease (AD) is characterized by amyloid plaques and neurofibrillary tangles (NFTs).
- Distinguishing between AD with only plaques (POAD) and plaques plus tangles (PTAD) is crucial for understanding disease heterogeneity.
Purpose of the Study:
- To compare clinical and pathological features of plaque-only Alzheimer disease (POAD) versus plaque and tangle Alzheimer disease (PTAD).
Main Methods:
- Autopsy series of 16 POAD and 32 PTAD patients with neuropsychological testing.
- Histopathological analysis of plaques, tangles, and cerebral amyloid angiopathy.
- Immunocytochemistry for phosphorylated tau (AT8), synaptic density, choline acetyltransferase (ChAT) activity, and APOE genotyping.
Main Results:
- POAD and PTAD showed similar initial cognitive decline but POAD patients had slower deterioration on the Mattis Dementia Rating Scale.
- POAD patients had older age at onset/death, fewer hippocampal NFTs, fewer neuritic plaques, and higher ChAT activity.
- POAD lacked neocortical NFTs but showed abnormal phosphorylated tau in neurons.
Conclusions:
- Clinically indistinguishable dementing syndromes occur with or without neocortical NFTs.
- Absence of neocortical NFTs is associated with older onset, slower decline, and potential contribution of subtle tau pathology.
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