a1 Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht, The Netherlands
a2 Department of Neurology, VU University Medical Centre, Amsterdam, The Netherlands
Background We investigated whether the predictive accuracy of mild cognitive impairment (MCI) for Alzheimer-type dementia (AD) in a clinical setting is dependent on age and the definition of MCI used.
Method Non-demented subjects older than 40 (n=320) who attended a memory clinic of a university hospital were reassessed 5 years later for the presence of AD. MCI was diagnosed according to the criteria of amnestic MCI, mild functional impairment (MFI), ageing-associated cognitive decline (AACD), and age-associated memory impairment (AAMI). The main outcome measure was the area under the curve (AUC) of a receiver operating characteristic (ROC) curve. Analyses were conducted on the entire sample and on subgroups of subjects aged 40–54, 55–69 and 70–85 years.
Results A diagnosis of AD at follow-up was made in 58 subjects. Four of them were in the 40–54 age group, 29 in the 55–69 age group and 25 in the 70–85 age group. The diagnostic accuracy in the entire sample was low to moderately high with AUCs ranging from 0.56 (AACD) to 0.75 (amnestic MCI). A good predictive accuracy with an AUC >0.80 was only observed in subjects aged 70–85 using the criteria of amnestic MCI (AUC=0.84).
Conclusions The predictive accuracy of MCI for AD is dependent on age and the definition of MCI used. The predictive accuracy is good only for amnestic MCI in subjects 70–85 years. As subjects with prodromal AD are often younger than 70, the usefulness of MCI as predictor of AD in clinical practice is limited.
(Received September 20 2006)
(Revised March 03 2007)
(Accepted March 06 2007)
(Online publication April 24 2007)