Characterization of Japanese-American men with a single neocortical AD lesion type.

Neocortical neuritic plaques (NP) and neurofibrillary tangles (NFT) are hallmarks of Alzheimer's disease (AD) and usually, both are present. The Honolulu-Asia Aging Study autopsy series includes a significant number of individuals with only one neocortical AD lesion type. These could represent an early phase of the AD process. If so, such individuals would be expected to share other clinical and pathological features of AD. We compared frequency of apolipoprotein epsilon E4 (APOE4) allele, average Braak stage, and burden of cerebral amyloid angiopathy (CAA) among the two single lesion type groups, a group without AD lesions, and groups with high and low frequencies of both AD lesions. Single AD lesion groups shared only the characteristics associated with their unique lesion type with the combined AD lesion group and did not have higher prevalence of dementia than the no AD lesion group. Only the NP+NFT group showed a "dose-response" relationship with greater probability of dementia with higher neocortical frequencies of either AD lesion. The single neocortical AD lesion groups do not appear to represent early AD.