P2-183: An evaluation of functional disability in mild cognitive impairment: Baseline impairment does not predict progression in the ACCORD study

Abstract

Patients who are classified as Cognitively–Impaired–Not–Demented (CIND) are at significantly increased risk of progression to dementia. Changes in functional ability define the transition to Alzheimer Disease (AD). However, the most sensitive predictors and patterns of functional decline remain to be fully determined. To evaluate the utility of the Disability Assessment of Dementia (DAD) scale in predicting and characterizing the progression of CIND to AD. The DAD is an informant–based instrument that measures both Instrumental Activities of Daily Living (IADLs) and Basic Activities of Daily Living (BADLs). A cohort of CIND subjects (n=70) was followed for two years within the Canadian Cohort Study of Cognitive Impairment and Related Dementias (ACCORD), of whom 31% progressed to AD (CIND–AD) while 69% remained stable (CIND–Stable). A comparison of DAD scores at entry and at year–2 was conducted between the CIND–AD and CIND–Stable groups with analysis of covariance (ANCOVA) adjusted for age, sex and education. Logistic regression, adjusted for the same variables, was used to assess the predictive ability of the total DAD scores. At baseline, there were neither significant differences between the total DAD scores of the CIND–AD and CIND–Stable (94.1±7.6 % and 94.8±10.8 % respectively), nor the BADL and IADL sub–scores. The mean DAD total change scores at year–2 were −12.0±19.2% for the CIND–AD group and +0.4±8.9% for the CIND–Stable group (p=0.002). Similarly, the rate of decline in both BADLs and IADLs was significantly greater (p=0.015 and p=0.002 respectively) in CIND–AD than in the CIND–Stable group. The baseline DAD score did not contribute significantly to the prediction of progression to AD (OR 1.0, 95% C.I. 0.9–1.1). As expected, individuals progressing to AD showed a greater decline in their functional abilities; however, the DAD total score at entry did not predict progression to AD. We anticipate that an evaluation of higher social functioning is likely required to detect the earliest significant changes in function that may herald or predict progression to AD.