Neuropsychological correlates of self-reported performance in instrumentalactivities of daily living and prediction of dementia

This study examines the relationships between performance on neuropsycholog ical rests and 4 instrumental activities of daily living (IADL) associated with an increased risk of dementia, in 1,792 nondemented elderly people inc luded in the Personnes Agees Quid (PAQUID) study. There was a decline of ne uropsychological performance on each test with increasing IADL dependency, in particular between Grades 1 and 2. Performances of the independent parti cipants were very homogeneous. Each IADL had different specific association s with the neuropsychological tests. A principal component analysis showed three main factors explaining 49.6% of variance. The first factor was the c ommon cognitive component of both instrumental tasks and neuropsychological tests. The second factor was specific to three IADL, whereas use of transp ortation had its main loading on the third factor. Only the first factor wa s predictive of the risk of incident dementia, suggesting that the predicti ve value of die 4 IADL was explained by their cognitive component.