The characteristics of patients with uncertain/mild cognitive impairment on the Alzheimer Disease Assessment Scale-cognitive subscale
Pyo G, Elble RJ, Ala T, Markwell SJ;
Commented by , 23 May 2006
Aim of the study
To examine the usefulness of the Alzheimer Disease Assessment Scale-cognitive subscale (ADAS-cog) in diagnosis and research on mild cognitive impairment (MCI).
Method
843 normal controls defined as age 55+, Mini Mental State Examination (MMSE) 26+, delayed recall score not lower than 1.5 SD below the mean for age peers, 135 uncertain/MCI defined as Clinical Dementia Rating (CDR) of 0.5, and 155 patients with early stages of Alzheimer’s disease (AD) defined as CDR 0.5 (N: 30) or 1.0 (N: 125), were compared on the ADAS-cog supplemented by the Delayed Recall subtest.
Results
The normal controls were same age as the uncertain/MCI, but of higher education and MMSE scores (mean of 28.95 and 26.36 respectively). ADAS-cog scores were significantly better on all subtests (using Conover’s multiple comparison P < 0.05) in normal controls vs uncertain/MCI subjects. There was no significant correlation between age, gender or education and ADAS-cog scores in the uncertain/MCI group.
Professor Gauthier's comments
The ADAS-cog can successfully discriminate individuals with MCI from normal elderly. Age and education do not play a significant role in making this discrimination. The total error score on the ADAS-cog was 3.10 SD below the mean of normal controls. The authors endorse using the total error score of the ADAS-cog over individual subtests in differentiating MCI patients from normal elderly.
This study is important because there is a genuine interest in early treatment of AD in its prodromal stage. Establishing the familiar ADAS-cog as a useful cognitive tool for this population will facilitate naturalistic cohort studies as well as therapeutic trials using cognitive training or pharmacological agents.