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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. bernicc@ccf.org



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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