P2‐035: Prediction of cognitive decline in normal older persons without subjective cognitive impairment: A seven year longitudinal study

Abstract

Recent studies have characterized a pre-Mild Cognitive Impairment (MCI), Subjective Cognitive Impairment (SCI) stage in the aging and dementia continuum beginning ~ 20 years prior to the onset of dementia in Alzheimer's disease (AD) (Reisberg, et al., Alzheimer's & Dementia, 2008; Reisberg and Gauthier, International Psychogeriatrics, 2008). It appears that predictors of SCI, in addition to overt cognitive decline, in normal older persons free of subjective complaints (No Cognitive Impairment [NCI]), have not previously been examined longitudinally. A consecutive series of healthy older persons with NCI, ≥ 40 years of age, was studied extensively at baseline and followed longitudinally over an 18 year study interval. Outcome was defined dichotomously as: (1) decline to a diagnosis of SCI, MCI, or dementia, or (2) absence of decline over the follow-up interval. Baseline predictors of subsequent decline were examined. 0f 60 healthy subjects with no cognitive impairment (NCI) seen at baseline, 47 subjects (78.3%) were followed over a mean of 6.7±3.1 years. Baseline characteristics of subjects followed (means±SDs), included: age, 64.1±8.9 years; education, 16.1±2.4 years; and MMSE, 29.6±0.8. The majority of subjects, 55%, were women. At the last period of observation, 10 subjects remained NCI, and 37 subjects declined. Of the decliners, 29 (78.4%) had SCI at the last observation, 7 (18.9%) had MCI, and 1 subject (2.7%) had AD. Significant baseline predictors of decline included age (p<0.01), and psychometric baseline scores on paragraphs initial recall, the digit symbol substitution test, WAIS digits forward, and a combinatorial psychometric measure (p < 0.05). In a logistic regression analysis, which controlled for baseline demographic variables (i.e., age, gender, and education) and follow-up time, three baseline variables contributed significantly to the probability of decline: paragraphs initial recall (p=0.028), WAIS digits forward (p=0.018), and the combinatorial psychometric deterioration score (p=0.050). Apart from age, overall psychometric test performance, and specific psychometric test variables, can predict decline in cognitively normal, healthy older persons who are free of Subjective Cognitive Impairment. These findings are of relevance for future treatment trials directed towards AD prevention more than 20 years prior to the advent of overt dementia.