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Arch Neurol. 2012 Jul;69(7):901-5.

Age and rate of cognitive decline in Alzheimer disease: implications for clinical trials.

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  • 1Lou Ruvo Center for Brain Health, Cleveland Clinic, Las Vegas, Nevada 89106, USA.



Factors that affect the rate of progression of Alzheimer disease (AD) need to be considered in the clinical trial designs of potential disease-modifying therapies.


To determine the influence of age on AD course in a clinical trial setting.


Pooled cohort study from 3 AD clinical trials of 18-month duration conducted by the Alzheimer Disease Cooperative Study group.


Alzheimer disease research centers from across the United States.


Four hundred seventy-one subjects with mild to moderate AD assigned to the placebo arm of 3 clinical trials.


The relationships between baseline age and rate of change in the Alzheimer Disease Assessment Scale–cognitive subscale (ADAS-cog) 11, Mini-Mental State Examination, Clinical Dementia Rating scale Sum of Boxes score, Alzheimer Disease Cooperative Study–activities of daily living scale, and Neuropsychiatric Inventory were analyzed using a mixed-effect regression model. Sample size calculation for possible future AD clinical trials lasting 18 months using the results of the change in ADAS-cog 11 by tertiles of age groups.


Older age at baseline was associated with a slower rate of decline in the ADAS-cog 11 and the Mini-Mental State Examination scores. Almost twice as many subjects aged 80 years and older compared with those aged younger than 70 years would be required to demonstrate a 30% treatment effect on the ADAS-cog 11 in an 18-month AD trial.


Subject age is an important factor to consider when defining the study population in and analyzing data from AD trials of potential disease-modifying therapies.

[PubMed - indexed for MEDLINE]
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