Abstract
OBJECTIVE: To investigate causal factors of functional impairment in old age in a longitudinal approach. DESIGN: A population-based prospective cohort study. SETTING: Elderly individuals were recruited via GP offices at six study centers in Germany. They were observed every 1.5 years over six waves. PARTICIPANTS: Three thousand two hundred fifty-six people aged 75 years and older at baseline. MEASUREMENTS: Functional impairment was quantified by the Lawton and Brody Instrumental Activities of Daily Living scale (IADL) and the Barthel-Index (BI). RESULTS: Fixed effects regressions revealed that functional impairment (IADL; BI) increased significantly with ageing (β=-.2; β=-1.1), loss of a spouse (β= .5; β=-3.1), not living alone in private household (β=-1.2; β=-5.5), depression (solely significant for IADL: β= .6) and dementia (β=-2.3; β=-18.2). The comorbidity score did not affect functional impairment. CONCLUSION: Our findings underline the relevance of changes in sociodemographic variables as well as the occurrence of depression or dementia for functional impairment. While several of these causal factors for functional decline in the oldest old are inevitable, some may not be, such as depression. Therefore, developing interventional strategies to prevent depression might be a fruitful approach in order to delay functional impairment in old age.