Preclinical syndromes predict dementia: the Sydney older persons study

Objectives-To identify if preclinical syndromes for Alzheimer's disease, va scular dementia, and Parkinson's disease and related dementias exist. Ident ification of dementia at early or even preclinical stages has important imp lications for treatment. Methods-A community dwelling sample of 647 subjects aged 75 and over at rec ruitment were followed up for a mean period of 3.19 years (range 2.61 to 4. 51 years). Each subject was asked to participate in a medical assessment wh ich included a standardised medical history examining both past and current health and medication usage; a neuropsychological battery (mini mental sta te examination, Reid memory test, verbal fluency, subsets of the Boston nam ing test and similarities, clock drawing and copied drawings) and physical examination. Preclinical syndromes for the three predominant dementias (Alz heimer's disease, vascular dementia and Parkinson's disease, and related de mentias) and their combinations were defined using cognitive, motor, and va scular features. Their longitudinal outcome as defined by death and dementi a incidence was examined. Results-Preclinical syndromes affected 55.7% (n = 299) of subjects. Preclin ical syndromes showed a trend for an increased odds of death (odds ratio 1. 72, p = 0.056) and a significantly increased odds of developing dementia (o dds ratio 4.81, p < 0.001). Preclinical syndromes were highly sensitive, de tecting 52 of SS (89.7%) incident dementias. Two hundred and sixteen of 268 (80.6%) preclinical subjects did not show dementia over the 3 year period (positive predictive value 19.4%). Subjects defined as having a combination of cognitive, extrapyramidal and vascular features were at greatest risk o f progressing to dementia. Conclusions-Preclinical syndromes were sensitive and significant predictors of dementia. In view of their poor positive predictive value, the preclini cal syndromes as defined in this study remain a research tool needing both definitional refinement and greater periods of observation. Multiple coexis tent preclinical disorders resulted in a greater incidence of dementia, pro viding evidence for an additive role between multiple disorders.