The validity and reliability of the Turkish version of Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) in patients with mild and moderate Alzheimer's disease and normal subjects

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2006

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Objectives: The cognitive subscale of the Alzheimer's Disease Assesment Scale (ADAS-Cog) is the most widely used test clinical trials dealing with Alzheimer's disease (AD). The aim of this study was to investigate the validity and reliability of the Turkish version of ADAS-Cog. Methods: Twenty-nine patients with AD, fullfilling NINCDS-ADRDA criteria of probable AD, who were in stage 3-5 according to the Global Deterioration Scale (GDS), and 27 non-demented control subjects with similar age, gender and educational status were recruited for the study. The Turkish version of ADAS-Cog, Standardized Mini Mental Status Examination (MMSE) and Short Orientation-Memory-Concentration Test (SOMCT) were applied to both of the groups. Interrater reliability, internal consistency, test-retest reliability; face validity, differential validity and convergent validity were statistically analyzed. Results: Both MMSE and ADAS-Cog have significantly differentiated patients with AD and control subjects (p < 0.001). A significant correlation was established between MMSE and ADAS-Cog scores in AD group (r: -0.739). ADAS-Cog was also highly significantly correlated with GDS (r: 0.720) and SOMCT (r: 0.738). For the group with AD, control and whole cohort coefficients of internal consistency, Cronbach's α: 0.800, 0.515, 0.873 were found respectively. Inter-rater reliability for total ADAS-Cog score was found as ICC: 0.99 and 0.98 and test-retest reliability was found as ICC: 0.91 and 0.95 for demented and nondemented subjects, respectively. Conclusion: The Turkish version of ADAS-Cog has been found to be highly reliable and valid in differentiating patients with mild and moderate AD from nondemented subjects. Copyright © 2006 John Wiley & Sons, Ltd.

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