P2‐239: IS CDR = .5 ASSOCIATED WITH WORSE OBJECTIVE MEASURES OF COGNITION IN A MIDDLE‐AGED SAMPLE? RESULTS FROM THE WISCONSIN REGISTRY FOR ALZHEIMER'S PREVENTION

The Clinical Dementia Rating (CDR) scale was developed to identify stages of cognitive decline along the Alzheimer's continuum. The CDR global rating has been shown to be a reliable indicator of dementia in older samples. Our study examined whether CDR was predictive of concurrent objective measures of cognition and functioning in a late-middle-aged sample enriched with a family history of AD. Participants from the Wisconsin Registry for Alzheimer's Prevention (WRAP) who had a CDR associated with their fourth wave of cognitive assessment and were free of neurological disorders known to affect cognition were included (n = 318; mean (sd) age = 63(6.1); 86.8% family history of AD (FH+); 39.6% APOE4 carriers; and 64.5% women). Baseline characteristics and wave 4 functional status of those with CDR's = 0 and .5 were compared using chi-square and t-tests. Cognitive outcomes included 4 factors assessed at wave 4 (Immediate Memory (IM), Verbal Learning and Memory (VLM), Speed and Flexibility (SF), and Working Memory (WM)). Analysis of covariance (ANCOVA) was used to examine whether CDR ratings predicted wave 4 cognition after adjusting for age, gender, and education. CDR scores included 0 (75.2% of sample) and .5. Those with CDR = .5 were significantly older at baseline (52.5(6.0) vs. 55.1(6.4), p = .001) and had worse WM and SF scores at baseline than those with CDR = 0. The CDR groups did not differ in gender, education, race, FH, APOE-4 status, or baseline IQ, IM and VLM. After adjusting for covariates, wave 4 CDR was a significant predictor of concurrent VLM (β = .28, p = .003), SF (β = .35, p = .004), and WM (β = .26, p = .03) such that mean cognitive scores were higher among those with CDR = 0. Median IADL, IQCODE, and MMSE scores at the time of CDR were normal for both CDR groups (16, 48, and 30, respectively). In this relatively young sample (mean age = 62.5), a CDR rating of .5 was associated with decrements in memory and executive function, aspects of cognition that are often associated with early AD. Longitudinal follow-up is needed to determine whether abnormal CDR scores at a mean age of 63 are associated with increased conversion to AD.