How do impairments in cognitive functions affect activities of daily living functions in older adults?

Abstract

The assessment of daily living activities could provide information about daily functions and participation restrictions to develop intervention strategies. The purposes of this study were to assess the scores of the Barthel Index (BI) and Lawton Instrumental Activities of Daily Living (IADL) scale in older adults with cognitive impairment and to explore the different effects that levels of cognitive functions have on changes in IADL functions. We recruited 31 participants with dementia, 36 with mild cognitive impairment (MCI), and 35 normal controls (NCs) from the neurology outpatient department of a regional hospital. The results of the demographic and clinical characteristics through the Lawton IADL scale, BI, Quick Mild Cognitive Impairment (Qmci) screen, Montreal Cognitive Assessment (MoCA), and Mini-Mental State Examination (MMSE), were collected on the same day and compared with the Kruskal-Wallis test, Wilcoxon rank-sum test, Fisher's exact test, and a multiple linear regression analysis, as appropriate. In the BI, bathing was the most discriminating activity to differentiate patients with MCI and dementia; in the Lawton IADL scale, medication responsibility and shopping were the most discriminating activities to differentiate NCs and patients with MCI, and patients with MCI and dementia, respectively. In addition, the predictors of changes in Lawton IADL scale scores were the problem-solving score of the Clinical Dementia Rating scale, a Qmci score of > 20.4 and an age of ≤ 81.2 years, a MoCA score of < 9.4 and an age of > 81.2 years, and the MMSE score and an age of > 81.2 years. This study adds to the evidence that the description of basic and instrumental daily activities is integrated in older adults with cognitive impairment. Notably, the Qmci is the most significant predictor of changes in IADL function for "young" older adults, as are the MoCA and MMSE for "old" older adults.

Fig 1. The plot of the fitted multiple generalized additive model (GAM) for estimating the partial effect of “Age” (years) on the “change score of the Lawton IADL scale”, adjusted for the effects of the “Problem solving score of the CDR” and the smoothed “MMSE score”.

The change score of the Lawton IADL scale = The current score of the Lawton IADL scale − The Lawton IADL scale at baseline. Lawton IADL scale = Lawton Instrument Activities of Daily Living scale; CDR = Clinical Dementia Rating scale; and MMSE = Mini-Mental State Examination. The cut-off value of 81.2 years for “Age” was estimated by the intersection of the smoothed red curve and the green straight line at Predicted value of Y = 0. The many little vertical bars (called the rugs) right above the X-axis indicated where the observed values of “Age” located. The technical details of the GAM plot were described in the Materials and methods section.