Clinical aspects of 'senile dementia of the tangle type'-- a subset of dementia in the senium separable from late-onset Alzheimer's disease.

There is a subset of dementia patients in the senium, in whom abundant neurofibrillary tangles (NFTs) are present mainly in the hippocampal region without significant numbers of senile plaques. This patient group was thought to be separable from those with Alzheimer's disease based on the results of ApoE allele analysis in addition to the substantial absence of amyloid beta deposits and has been designated as senile dementia of the tangle type (SDT). The clinical pictures of 4 autopsied patients with different amounts of NFTs were examined to characterize the clinical aspects of this type of senile dementia. SDT generally occurs in very old patients and was estimated to account for about 4-6% of patients with dementia in the senium excluding vascular dementia. Clinically, long-lasting memory disturbance is more prominent and personality as well as cognitive functions tend to be preserved. Delirium and other psychotic symptoms are often observed. NFTs and accompanying neuronal loss in the limbic, mainly in the hippocampal, region could be responsible for dementia.