Objective: To describe the restriction in instrumental activities of daily living (IADL) in mild cognitive impairment (MCI) and to assess the impact of IADL restriction on the progression to dementia and on MCI reversibility.
Methods: The study sample included 1,517 participants of the PAQUID cohort, visited at 8- and 10-year follow-ups. Subjects classified as having MCI had no dementia but a cognitive deficit according to five neuropsychological tests. Four IADL (telephone, transports, medication, finances) were assessed and considered restricted if at least two of them were not performed at the highest level of performance. Cross-sectional and longitudinal analyses were conducted.
Results: A total of 285 subjects were classified as having MCI at baseline, and 15.2% developed dementia within 2 years. MCI subjects were more frequently IADL restricted (34.3%) than controls (5.4%) but less than those with dementia (91.1%). The IADL-restricted MCI subjects were more likely to develop dementia over 2 years (30.7%) than the nonrestricted ones (7.8%). In multivariate analyses, the odds ratio for dementia was 7.4 (CI: 3.3 to 16.5) in the IADL-restricted MCI and 2.8 (CI: 1.3 to 6.0) in the non-IADL-restricted MCI compared with the non-IADL-restricted controls. IADL restriction also lowered the chance of reversibility to normal, observed in 10.7% of the restricted MCI and 34.7% of the nonrestricted MCI.
Conclusions: Inclusion of instrumental activities of daily living restriction in the criteria of mild cognitive impairment improves the prediction of dementia and the stability of this status over time. Conversely, its exclusion results in inappropriate selection of subjects with a low probability of short-term progression to dementia.