Predictors of perceived functional ability in early-stage dementia: self-ratings, informant ratings and discrepancy scores

Objective: Assessing functional ability is an important element in diagnosing and monitoring the progression of dementia, with research suggesting a link between functional ability and cognition. We investigated the predictors of total score and individual item functional ratings made by people with dementia (PwD), carers of PwD and the resulting discrepancy score. Methods: People with early-stage Alzheimer's disease, vascular or mixed dementia (n = 100) and their carers completed the Functional Activities Questionnaire. PwD also completed tests of memory, verbal executive function, language and cognitive screening, and provided ratings of mood. Carers provided a rating of stress. Results: Immediate memory predicted self-rated functioning, whereas carer stress predicted informantrated functioning. Letter fluency predicted the discrepancy between self-rated and informant-rated functioning. For self-rated functioning, the direction and pattern of the individual item predictors suggested a degree of functional awareness. Informant ratings were dominated by carer stress and, to a lesser extent, everyday memory. The discrepancy scores were also predicted by carer stress and everyday memory, but also letter fluency. Conclusions: Self-rated functioning showed evidence of awareness based on the direction and pattern of significant individual item predictors. Informant ratings, however, were found to be significantly influenced by carer stress. The findings have implications for the use of perceived functional ratings in clinical and research settings. Copyright (C) 2014 John Wiley & Sons, Ltd.