Restriction in complex activities of daily living in MCI: impact on outcome
Peres K, Chrysostome V, Fabrigoule C, Orgogozo JM, Dartigues JF, Barberger-Gateau P;
Commented by , 24 Aug 2006
Aim of the study
To describe if there are restrictions in specific instrumental activities of daily living (IADL) that predict reversibility or progression to dementia.
Method
1,517 participants in the community-based PAQUID cohort from Southern France were visited at 8- and 10-year follow-ups. The MCI subjects had a cognitive deficit according to five neuropsychological tests but were not clinically demented. Four IADL (telephone, transports, medication, finances) were assessed and considered restricted if at least 2 out of 5 were not performed at the highest level of performance.
Results
285 had MCI at baseline, and 15.2% developed dementia within 2 years. MCI subjects were more frequently IADL restricted (34.3%) than controls (5.4%) but less than patients with dementia (91.1%). The IADL-restricted MCI subjects were more likely to progress to dementia over 2 years than the non-restricted ones (30.7% versus 7.8%); odds ratio of 7.4 [CI: 3.3 to 16.5] versus 2.8 [CI: 1.3 to 6.0]).
The MCI subjects without IADL restriction were more likely to revert back to normal (34.7% versus 10.7%).
Professor Gauthier's comments
The authors conclude that inclusion of IADL restriction, particularly for the four items known to be most sensitive to early dementia, improved the prediction of dementia and the stability of this status (e.g. no reversal back to normal) over a period of time as short as 2 years. This study is important because it helps define the MCI population most at risk of progression to dementia, usually Alzheimer’s disease (AD), and may facilitate the evaluation of disease-modifying treatments.
These clinical observations can be supplemented by apolipoprotein E (APOE ε4) genotyping: results from the Cache County Study confirm the very high risk of progression to AD in MCI subjects with at least one APOE ε4 allele (ref. 1). [11C]PIB scanning also appears promising in detecting subjects with abnormal amyloid loading in asymptomatic individuals (ref. 2).
It is thus possible to predict that persons with cognitive complaints who are found to have some abnormal neuropsychological tests but that are not clinically demented, will be offered a combination of clinical and biological predictors for progression to dementia. This strategy will make sense if there are specific disease-modifying treatments, such as the amyloid-specific therapies under study (tramiprosate or Alzhemed, R-flurbiprofen or Flurizan, bapineuzumab or AAB-001).
All this promising research must not detract from the day to day reality of dealing with persons who have memory complaints: most will not have dementia. They should be made aware of their risk state and their vascular risk factors treated appropriately (ref. 3).
References
1. Tschanz JT, Welsh-Bohmer KA, Lyketsos CG, Corcoran C, Green RC, Hayden K, et al. Conversion to dementia from mild cognitive disorder: the Cache County Study. Neurology 2006; 67 (2); 229-234
2. Mintun MA, Larossa GN, Sheline YI, Dence CS, Lee SY, Mach RH, et al. [11C]PIB in a nondemented population: potential antecedent marker of Alzheimer disease. Neurology 2006; 67 (3); 446-452
3. Gauthier S, Reisberg B, Zaudig M, Petersen RC, Ritchie K, Broich K, et al. Mild cognitive impairment. Lancet 2006; 367 (9518); 1262-1270