Functional autonomy in dementia of the Alzheimer’s type, mild cognitive impairment, and healthy aging: a meta-analysis

Background: Activities of daily living (ADL) are fundamental skills required to independently care for oneself and are categorized in basic (BADLs) and instrumental (IADLs) activities of daily living. ADL evaluation is of paramount importance in clinical practice to discriminate between healthy individuals (HC) and patients with mild cognitive impairment (MCI) or Alzheimer’s disease (AD). However, it is unclear whether and to what extent BADL and IADL deficits occur in MCI, when compared with AD. Therefore, the present study aimed at comparing performance on both BADLs and IADLs in HC, MCI, and AD. Methods: Three electronic databases were consulted for studies comparing total BADLs/IADLs, and single BADLs/IADLs in AD, MCI, and HC (comparisons: AD versus MCI, AD versus HC, MCI versus HC). Ninety-six studies were included in the meta-analysis with random effect models (Hedges’ g). Meta-regression was performed to evaluate the effect of clinical variables on ESs. Results: AD group had more difficulties in BADLs and IADLs than HC and MCI groups; people with MCI showed more difficulties in both IADLs and BADLs than HC. The meta-regression analysis revealed that the percentage of males in the samples was a significant predictor of the ES in the meta-analysis comparing total BADL scores between MCI and HC; in the comparison between AD and HC, age at evaluation predicted the ES on some single IADLs: preparing food, handling medication, and finances. Conclusions: In MCI, it should be considered not only a decline of IADLs but also subtle decline of BADL abilities.