Distinctive clinical features of Mild Cognitive Impairment with subcortical cerebrovascular disease.
Galluzzi S, Sheu CF, Zanetti O and Frisoni GB;
Commented by , 18 Feb 2005
Aim of the study
To identify clinical and neuropsychoplogical features that best differentiate amnestic MCI (aMCI) from MCI with subcortical cerebrovascular disease (svMCI).
Method
Patients enrolled within a prospective study on the natural history of early cognitive impairment between 1996 and 2000 with a diagnosis of aMCI or svMCI were assessed with neuropsychological battery including the Wisconsin Card Sorting Test, standardized gait and mobility scales, urinary symptoms from the Barthel Index and behavior using the NeuroPsychiatric Inventory (NPI).
Stepwise logistic regression analysis and areas under the receiver operating characteristic curve and 95% confidence intervals (CIs) were used for the statistical analysis.
Results
The most accurate domains to distinguish aMCI from scMCI were the extrapyramidal sign scale (0.75, 95% CI 0.61-0.89), letter fluency (0.75, 95% CI 0.61-0.90), irritability on the NPI and urinary dependence (0.66, 95% CI 0.49-0.82), digit span forward (0.59, 95% CI 0.41-0.77).
The overall accuracy of a model compounding information from main and supportive features was 0.98, 95% CI 0.94-1.0.
Professor Gauthier's comments
Within the heterogeneous conditions underlining the syndrome of MCI, the amnestic subtype has been the best characterized so far thanks to the work of Ron Petersen and John Morris.
A recent Expert Conference convened by the International Psychogeriatric Association is leading to the conclusion that aMCI may be a prodromal stage of Alzheimer’s disease (AD), potentially amenable to early pharmacologic treatment, although studies so far have been disappointing.
On the other hand there are many other causes of MCI with a different prognosis and therapeutic approach, including svMCI which is highly prevalent in population studies where it is most often referred to as "Cognitive Impairment No Dementia" of vascular etiology (CIND-Vasc).
The authors of this article have modified the available research diagnostic criteria for subcortical vascular dementia and applied them in a clinical population of aMCI and svMCI.
They then compared the two populations in terms of neuropsychological tests, gait impairment and extrapyramidal signs, urinary and behavior.
The main value of this study is the operational definition of scMCI which was badly needed in order to move forward in prospective studies in clinics and general populations in order to reliable define what could be of the most common type of MCI, amenable to secondary prevention towards AD or vascular dementia using a strict control of vascular risk factors.
References
See for example the following articles:
Petersen RC, Doody R, Kurz A et al. Current concepts in mild cognitive impairment. Arch Neurol 2001; 58 (12); 1985-1992
Morris JC, Storandt M, Miller JP et al. Mild cognitive impairment represents early-stage Alzheimer's disease. Arch Neurol 2001; 58 (3); 397-405
In press: Petersen R and Morris J. MCI as a clinical entity and treatment target. Arch Neurol 2005 (to be published in September, probably)