Cognition, Gender, and Functional Abilities in Alzheimer's Disease: How are They Related?

Background: Few studies have investigated in detail which factors influence activities of daily (ADL) in Alzheimer's disease (AD). Objective: To assess the influence of cognitive, gender, and other factors on ADL in patients with mild to moderate AD. Methods: This study is part of the Prospective Registry on Dementia in Austria (PRODEM) project, a multicenter dementia research project. A cohort of 221 AD patients (130 females; means: age 76 years, disease duration 34.4 months, MMSE 22.3) was included in a cross-sectional analysis. Everyday abilities were assessed with the Disability Assessment for Dementia scale, and cognitive functions with the CERAD plus neuropsychological test battery. Two models of multiple linear regressions were performed to find factors predicting functional decline, one entering demographical and disease related factors, and a joint model combining demographical and disease variables with neuropsychological scores. Results: Non-cognitive factors explained 18%, whereas the adding of neuropsychological variables explained 39% of variance. Poor figural and verbal memory, constructional abilities, old age, longer disease duration, depression, and male gender were independent risk factors for reduced ADL. Instrumental and basic ADL were predicted by similar factors, except gender (predicting only instrumental ADL) and phonological fluency (predictor of basic ADL). Conclusion: In addition to demographical factors, disease duration, and depression, neuropsychological variables are valuable predictors of the functional status in AD in an early disease stage.