A SYSTEMATIC REVIEW OF CHANGE POINT STUDIES ON COGNITIVE AND NEUROLOGIC OUTCOMES PRECEDING DEMENTIA

• Published in: Innovation in aging 2017-07, Vol.1 (suppl_1), p.241-241
• Main Authors: Graham, R., Karr, J.E., Muniz, G., Hofer, S.M.
• Format: Article
• Language: English
• Subjects: Abstracts
• ISSN: 2399-5300; 2399-5300
• DOI: 10.1093/geroni/igx004.891

Older adults who ultimately develop dementia experience accelerated cognitive decline long before diagnosis. The current systematic review aimed to summarize the literature on preclinical change points (CPs) in relation to mild cognitive impairment (MCI) and dementia, identifying the order in which cognitive and neurological outcomes decline and factors that modify the onset of decline. Eligible studies included preclinical MCI/dementia CP models for cognitive/neurological outcomes from longitudinal cohorts free of early-onset dementia or concurrent neurological disorders associated with cognitive decline. The search protocol yielded 16 eligible studies describing 9 cohorts (1 pre-MCI, 8 pre-dementia). Only the MCI cohort involved neuroimaging and motor outcomes, identifying CPs for increased ventricular cerebrospinal fluid volume (CP=3.66 years before onset [95% CI: 0.75–5.58]) and white matter (WM) hyperintensities (10.58 years [5.15-Unknown]). Gait resulted in the earliest CP at 12.10 years (8.10-Unknown), while finger tapping declined after diagnosis. Across domains, cognitive abilities declined roughly 3–4 years prior to MCI. The earliest observed CP for dementia was perceptual speed (10.90 years [7.50–14.40]). Verbal memory was most commonly measured, with CPs ranging from 1.00–8.60 years pre-diagnosis. The latest cognitive ability to decline was reading ability (0.40 years [-0.10–0.11]). Greater education, female gender, and involvement in cognitively-stimulating activities significantly delayed CP onset. CPs preceding Alzheimer’s disease occurred earlier than CPs preceding vascular dementia. The findings from this systematic review suggest that neurological and cognitive changes occur long before MCI/dementia diagnoses. Lifestyle, dementia type, and gender influence the onset of decline, but few studies evaluated CP moderators.