Short-term clinical outcomes for stages of NIA-AA preclinical Alzheimer disease
Exclusive author commentary
Knopman DS et al. – Despite the short follow–up period, the operationalization of the new preclinical Alzheimer disease (AD) recommendations confirmed that advancing preclinical stage led to higher proportions of subjects who progressed to MCI or dementia.Methods
- Using previously developed operational definitions of the 3 stages of preclinical AD, the authors examined the outcomes of subjects from the Mayo Clinic Study of Aging diagnosed as cognitively normal who underwent brain MRI or [18F]fluorodeoxyglucose and Pittsburgh compound B PET, had global cognitive test scores, and were followed for at least 1 year.
- Of the 296 initially normal subjects, 31 (10%) progressed to a diagnosis of mild cognitive impairment (MCI) or dementia (27 amnestic MCI, 2 nonamnestic MCI, and 2 non-AD dementias) within 1 year.
- The proportion of subjects who progressed to MCI or dementia increased with advancing stage (stage 0, 5%; stage 1, 11%; stage 2, 21%; stage 3, 43%; test for trend, p < 0.001).
Dr. Knopman (06/13/2012) comments:
Our results show that the underlying model of AD pathophysiology that is the basis for the preclinical AD designation reflects increasing risk for cognitive decline among cognitively normal persons. Although these observations are strictly of conceptual and research value at the present, they offer a blueprint for how identification of at-risk cognitively normal persons could proceed if or when secondary prevention trials for Alzheimer's disease become feasible.