Instrumental activities of daily living predicting MCI

Abstract

We can assume that any cognitive deficits assessable by neuropsychological testings must have a measurable impact on abilities in daily living. Consequently, we can hypothesize that subtle restriction in complex Activities of Daily Living (ADL) must be observed early in the course of dementia as observed in neuropsychology and improves the prediction of subsequent dementia. The Paquid cohort is an epidemiological study of cerebral and functional aging, initiated in 1988 on elderly community-dwellers in southwestern France and still on going after 20 years of follow-up. Restriction, even mild, in four specific Instrumental ADLs (telephone, transportation, medication, finances) was studied as particularly predictive of dementia. First, the IADL-restricted MCI had a greater risk of dementia in the two following years (OR = 7.4, 95%CI = 3.3-16.5) compared with the non-IADL-restricted controls. The risk for the non-restricted MCI was 2.8 (95%CI = 1.3-6.0). IADL-restriction also lowered the chance of reversibility to normal. Another analyses showed that 10 years before the clinical diagnosis of dementia, the future cases had already greater IADL-restrictions, and particularly for handling finances. After controlling for age, gender, and education, IADL-restricted subjects at baseline had a higher risk of dementia 10 years later (OR = 2.6, 95%CI = 1.2-5.4). Finally, recent findings showed that IADL-restriction and Subjective Memory Complaint (SMC) had significant but radically different clinical meanings in women and men. IADL-restriction at baseline was associated with an increased risk of dementia only in men (HR = 2.5, 1.6-4.0), whereas SMC did not (p = 0.97). The reverse was observed in females, in whom SMC almost doubled the risk (1.46 to 2.38), without any association with IADL-restriction once controlled for SMC. Restriction, even subtle, in complex activities of daily appears to be a strong predictor of subsequent dementia. Abilities in daily living as well as their evolution over time may represent a simple and useful screening tool in general population to facilitate an earlier and a more egalitarian access to specialized unit where more sophisticated diagnostic tools are available. However, further researches are necessary to refine this functional assessment to be more sensitive to very early signs of the disease and more specific of the dementia process.