[Diagnostic value and functional correlations of the ADAS-Cog scale in Alzheimer's disease: data on NORMACODEM...

The aims of this study were to assess the criterion validity of Alzheimer's Disease Assessment Scale (ADAS) and its cognitive subscale (ADAS-Cog) for the diagnosis of Alzheimer's disease (AD), and to determine their different cut-off scores and sensitivity and specificity values. In addition, we also attempted to study the possible correlations between cognitive scores (ADAS) and functional measures.

451 subjects were studied (254 controls, 86 subjects with mild cognitive impairment and 111 patients with AD). ADAS total score was obtained by adding the cognitive (ADAS-Cog) and non-cognitive (ADAS-Nocog) scales. Scores were adjusted for age and formal education. For assessing the possible correlation between cognitive and functional measures, the following instruments were administered: Rapid Disability Rating Scale-2 (RDRS-2), Blessed Dementia Rating Scale (BDRS) and the Interview for the Deterioration of Daily Living in Dementia (IDDD).

ROC curves and Pearson correlation coefficient.

ADAS best cut-off score for dementia was > or = 17 providing sensitivity and specificity values of 90.09% and 85.88 % respectively, while for the ADAS-Cog best cut-off score was > or = 12 with sensitivity and specificity values of 89.19 % and 88.53 % respectively. In both cases scores were adjusted for age and formal education. The area under the ROC curve was 0.95 and 0.94 respectively. Highly significant correlations were found for ADAS and 19 ADAS-Cog with the functional scales studied.

Both, ADAS and ADAS-Cog report good validity in terms of sensitivity, specificity and as predictive value for AD. Moreover, significant correlations were found between the functional impairment observed in patients with AD and the overall scores achieved in the ADAS and ADAS-Cog.