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Abstract(s)
Background: Dementia and cognitive impairment associated with aging are a major medical and social concern.
Neuropsychological testing is a key element in the diagnostic procedures of Mild Cognitive Impairment (MCI), but
has presently a limited value in the prediction of progression to dementia. We advance the hypothesis that newer
statistical classification methods derived from data mining and machine learning methods like Neural Networks,
Support Vector Machines and Random Forests can improve accuracy, sensitivity and specificity of predictions
obtained from neuropsychological testing. Seven non parametric classifiers derived from data mining methods
(Multilayer Perceptrons Neural Networks, Radial Basis Function Neural Networks, Support Vector Machines, CART,
CHAID and QUEST Classification Trees and Random Forests) were compared to three traditional classifiers (Linear
Discriminant Analysis, Quadratic Discriminant Analysis and Logistic Regression) in terms of overall classification
accuracy, specificity, sensitivity, Area under the ROC curve and Press’Q. Model predictors were 10
neuropsychological tests currently used in the diagnosis of dementia. Statistical distributions of classification
parameters obtained from a 5-fold cross-validation were compared using the Friedman’s nonparametric test.
Results: Press’ Q test showed that all classifiers performed better than chance alone (p < 0.05). Support Vector
Machines showed the larger overall classification accuracy (Median (Me) = 0.76) an area under the ROC (Me =
0.90). However this method showed high specificity (Me = 1.0) but low sensitivity (Me = 0.3). Random Forest
ranked second in overall accuracy (Me = 0.73) with high area under the ROC (Me = 0.73) specificity (Me = 0.73)
and sensitivity (Me = 0.64). Linear Discriminant Analysis also showed acceptable overall accuracy (Me = 0.66), with
acceptable area under the ROC (Me = 0.72) specificity (Me = 0.66) and sensitivity (Me = 0.64). The remaining
classifiers showed overall classification accuracy above a median value of 0.63, but for most sensitivity was around
or even lower than a median value of 0.5.
Conclusions: When taking into account sensitivity, specificity and overall classification accuracy Random Forests
and Linear Discriminant analysis rank first among all the classifiers tested in prediction of dementia using several
neuropsychological tests. These methods may be used to improve accuracy, sensitivity and specificity of Dementia
predictions from neuropsychological testing.
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Citation
BMC Research Notes, 4:299