ADAS-Cog explained

The Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) is a brief neuropsychological assessment used to assess the severity of cognitive symptoms of dementia. It is one of the most widely used cognitive scales in clinical trials^[1] and is considered to be the “gold standard” for assessing antidementia treatments.^[2]

The ADAS-Cog is one half of the Alzheimer's Disease Assessment Scale (ADAS), which also contains a non-cognitive subscale (ADAS-Noncog), which includes 10 tasks which assess mood and behavioural changes which may occur in Alzheimer's disease and other forms of dementia.^[2]

The ADAS-Cog consists of 11 tasks:

• Word Recall Task
• Naming Objects and Fingers
• Following Commands
• Constructional Praxis
• Ideational Praxis
• Orientation
• Word Recognition Task
• Remembering Test Directions
• Spoken Language
• Comprehension
• Word-Finding Difficulty

Different versions

Since its original creation in 1980s there have been many alternate versions of the ADAS-Cog created for various reasons. A review found 31 modified versions of the ADAS-Cog,^[2] these include:

• ADAS-Cog-IRT: Uses the standard 11 items from the ADAS-Cog but calculates the score based on item response theory. Using this method each question in the test is given a different value based on the difficulty, which is determined by how frequently it is answered correctly or incorrectly by a large reference group of participants.^[3]
• ADAS-Cog Plus: Developed to be more responsive to the early stage deficits seen is mild cognitive impairment. It includes the standard ADAS-Cog with additional tests to assess executive function and day-to-day function.^[4]
• VADAS-Cog: The VADAS-Cog is a variant the ADAS-Cog adapted to assess people with vascular dementia. It consists of the standard ADAS-Cog with additional measures for attention, working memory, executive function and verbal fluency.^[5]

Notes and References

1. Connor, D. J. . Sabbagh, M. N. . amp . Administration and Scoring Variance on the ADAS-Cog . Journal of Alzheimer's Disease . 15 . 3 . 461–464 . 2008 . 10.3233/JAD-2008-15312. 2727511 .
2. Kueper, J. K. . Speechley, M. . Montero-Odasso, M. . amp . The Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog): Modifications and responsiveness in pre-dementia populations. A narrative review . Journal of Alzheimer's Disease . 63 . 2 . 423–444 . 2018 . 10.3233/JAD-1709.
3. Balsis, S. Unger . A. A., Benge . J. F. . Geraci, L. . Doody, R. S. . amp . Gaining precision on the Alzheimer's Disease Assessment Scale-cognitive: A comparison of item response theory based scores and total scores. . Alzheimer's & Dementia . 8 . 288–293 . 2015 . 10.1016/j.jalz.2011.05.2409.
4. Skinner, J. . Carvalho, J. O. . Guy, G. P. . Thames, A. . Zelinski, E. . Crane, P. K. . Gibbons, L. E. . amp . The Alzheimer’s Disease Assessment Scale-Cognitive-Plus (ADAS-Cog-Plus): An expansion of the ADAS-Cog to improve responsiveness in MCI . Brain Imaging and Behavior. 6 . 4 . 489–501 . 2012 . 10.1007/s11682-012-9166-3. 3873823 .
5. Ferris, S. H. . General measures of cognition . International Psychogeriatrics. 15 . S1. 215–217 . 2005 . 10.1017/S1041610203009220 .