title: Alzheimer disease pathology in subjects without dementia in 2 studies of aging: the Nun Study and the Adult Changes in Thought Study.
abstract: Individuals with antemortem preservation of cognition who show autopsy evidence of at least moderate Alzheimer disease (AD) pathology suggest the possibility of brain reserve, that is, functional resistance to structural brain damage. This reserve would, however, only be relevant if the pathologic markers correlate well with dementia. Using data from the Nun Study (n = 498) and the Adult Changes in Thought (ACT) Study (n = 323), we show that Braak staging correlates strongly with dementia status. Moreover, participants with severe(Braak stage V-VI) AD pathology who remained not demented represent only 12% (Nun Study) and 8% (ACT study) of nondemented subjects. Comparison of these subjects to those who were demented revealed that the former group was often significantly memory-impaired despite not being classified as demented. Most of these nondemented participants showed only stage V neurofibrillary pathology and frontal tangle counts that were slightly lower than a comparable (Braak stage V) dementia group. In summary, these data indicate that, in individuals with AD-type pathology who do not meet criteria for dementia, neocortical neurofibrillary tangles are somewhat reduced and incipient cognitive decline is present. Our data provide a foundation for helping to define additional factors that may impair, or be protective of, cognition in older adults.
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA. santa013@umn.edu
authors.forename: Karen S
authors.initials: KS
authors.lastname: SantaCruz
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Sonnen
authors.forename: Maryam Kherad
authors.initials: MK
authors.lastname: Pezhouh
authors.forename: Mark F
authors.initials: MF
authors.lastname: Desrosiers
authors.forename: Peter T
authors.initials: PT
authors.lastname: Nelson
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Tyas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D000544:Alzheimer Disease / Q000150:complications / Q000453:epidemiology / Q000235:genetics / Q000473:pathology*; D001057:Apolipoproteins E / Q000235:genetics; D001921:Brain / Q000473:pathology*; D003072:Cognition Disorders / Q000209:etiology* / Q000473:pathology; D003704:Dementia / Q000150:complications / Q000453:epidemiology / Q000473:pathology; D005260:Female; D006801:Humans; D016631:Lewy Bodies / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D016874:Neurofibrillary Tangles / Q000473:pathology; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D001057:Apolipoproteins E