Instrumental activities of daily living as a screening tool for cognitive impairment and dementia in elderly community dwellers

Abstract

Objective: To identify which Instrumental Activities of Daily Living (IADL) are related to cognitive impairment, independent of age, sex, and education; to assess the performance of an IADL score using these items in screening for cognitive impairment and dementia in elderly community dwellers.

Design: Survey based on the baseline interview of the PAQUID study on functional and cerebral aging.

Setting: Community survey in 37 randomly selected parishes in Gironde, France.

Subjects: Random sample of 2,792 community dwellers aged 65 and over (participation rate: 69%).

Measurements: Two-phase screening: (1) functional assessment, Mini-Mental State Examination (MMSE) and DSM-III criteria for dementia; (2) in DSM-III-positive patients, NINCDS-ADRDA criteria applied by a neurologist. Functional assessment: IADL scale of Lawton and Brody. Criterion standards: cognitive impairment: MMSE score lower than 24; dementia: DSM-III and NINCDS-ADRDA criteria.

Results: Four IADL items are correlated with cognitive impairment independent of age, sex, and education: telephone use, use of means of transportation, responsibility for medication intake, and handling finances. A score adding the number of IADL dependencies has a sensitivity of 0.62 and a specificity of 0.80 at the lowest cut-off point (score > 0) for the diagnosis of cognitive impairment. The same score at the same cut-off has a sensitivity of 0.94 and a specificity of 0.71 for the diagnosis of dementia. The prevalence of dementia (2.4%) is reduced by a factor of 12 in subjects independent for the four IADL.

Conclusion: The four IADL score could be incorporated into the screening procedure for dementia in elderly community dwellers.