Predictive value of 6-month decline in ADAS-cog for survival without severe Alzheimer's disease.

BACKGROUND/AIMS: To determine the predictive value of the 6-month evolution of the ADAS-cog score in initially mild to moderate Alzheimer's disease (AD) patients on the risk of death or severe dementia (MMSE <10) within 2 years.

METHODS: Cognition was assessed every 6 months using the ADAS-cog scale in the Real.fr study, a cohort of AD patients. Six classes of ADAS-cog evolution were distinguished, from the severest deterioration (decline >or=7 points) to the greatest cognitive improvement (gain >or=4 points).

RESULTS: Among 536 AD patients, 53 (9.9%) had a 6-month decline of 7 points or more. This group with the severest deterioration was significantly associated with the risk of severe dementia or death at 2 years (relative risk, RR = 3.8, 95% confidence interval, CI = 2.1-6.8), even after adjustment for baseline MMSE, disability and ADAS-cog score (RR = 2.6, 95% CI = 1.4-5.0). In addition, subjects with a decline by at least 4 points were also at greater risk of severe dementia.

CONCLUSION: These results confirm the value of the ADAS-cog scale as a judgement criterion in clinical trials since it is a good surrogate marker of long-term prognosis. The proportion of fast decliners on the ADAS-cog could be a helpful judgement criterion for future trials in AD.