Increasing the Sensitivity of Functional Status Assessment in the Preclinical Range (Normal to Mild Cognitive Impairment): Exploring the IADL-Extended Approach

Abstract

Background/Aims: Dementia exhibits an insidious onset consisting of cognitive, behavioral, and functional impairment. We explored a functional continuum that extends assessment beyond the clinical instrumental activities of daily living (IADL) range and into advanced activities of daily living. Methods: We examined the predictive power (Cox regression; n = 2,471) of a unidimensional IADL-extended (IADL-x) scale for incident mild cognitive impairment (MCI). We also examined “time to MCI” as an outcome measure. Results: Each additional task endorsed on the IADL-x hierarchy (e.g., endorsing participation in 6 vs. 5 activities) resulted in a 10% reduction in MCI risk (HR 0.90, 95% CI 0.85–0.94, p < 0.001). For the fully adjusted model the risk reduction dropped to 6%. The odds of incident MCI within 2 years (for those below the median IADL-x total score) was 2.5 times higher (OR 2.60, 95% CI 1.52–4.4, p < 0.001) and 2 times higher for incident MCI within the next 5 years (OR 1.93, 95% CI 1.76–3.2, p < 0.01). Conclusion: The IADL-x metric appears to be a valid approach for determining the risk of MCI based on one’s position along a formal hierarchy of function.