Performance-Based vs Informant-Reported Instrumental Activities of Daily Living in Predicting Dementia

OBJECTIVES: Identifying individuals at risk of developing dementia may be aided by early detection of functional impairments. The aims of the present study were to examine differences in informant-reported and performance-based measures of instrumental activities of daily living (IADL) and to assess whether a performance-based IADL measure contributes additional unique variance over informant reports in predicting incident dementia over 4 years. DESIGN: Prospective cohort study (Sydney Memory and Ageing Study). SETTING: Eastern Suburbs, Sydney, Australia. PARTICIPANTS: 307 community-dwelling individuals (60.6% female) aged between 76 and 96 years with normal cognition (NC; n = 190) or mild cognitive impairment (MCI; n = 117). METHODS: IADL ability was assessed with the performance-based Sydney Test of Activities of Daily Living in Memory Disorders (STAM) and the Bayer-Activities of Daily Living (B-ADL) informant report, at baseline and 4-year follow-up. Covariates included age, sex, education, Mini-Mental State Examination and Geriatric Depression Scale scores, arthritis, vision impairment, cardiovascular risk, and number of medications. Logistic regressions were conducted to examine the longitudinal association between the 2 types of IADL measures and incident dementia. RESULTS: Logistic regressions showed that performance-based IADL impairment at baseline [odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.77, 0.90; P < .001] and decline in performance-based IADL function (OR = 0.82, 95% CI 0.73, 0.91; P < .001) were associated with incident dementia over 4 years, with the association provided by the STAM being statistically significant over and above the B-ADL. CONCLUSIONS AND IMPLICATIONS: Performance-based measures of IADL can predict progression to dementia over 4 years beyond that provided by an informant report of IADL. Performance-based IADL measures are promising tools for clinical practice to identify individuals at greater risk of developing dementia.