Limitations in activities of daily living and instrumental activities of daily living capacity in a representative sample: disentangling dementia- and mobility-related effects.

A representative sample of the Leipzig population aged 75 years and older showed 61.8% of the participants with relevant deficits in their capacity for independent living, according to a combined activities of daily living/instrumental activities of daily living (ADL/IADL) scale. The quantity and quality of care needed almost exponentially increases above 85 years of age. Looking at potential reasons for ADL/IADL limitations, 44% of variance in single ADL/IADL activities and 75% of the combined ADL/IADL sum score could come from a minimal set of predictor variables. Most important are dementia- or mobility-related declines, but living conditions also explain small but significant amounts of variance. These seem initially impressive, yet analyses showed about half the explained variances shared among the mobility and dementia indicators, limiting the use not only of ADL/IADL sum scores but of many single ADL/IADL items as well. Before deriving specific conclusions from variations in ADL/IADL instruments, one must note that the data suggest that interpretations of covariations--whether for health/mobility or dementia--are useful and substantial only if both indicators/predictors are verified. The information given captures the mobility- and dementia-related variance if ADL/IADL items, facilitating more specific scale developments.