Summary

Previous studies have suggested that anti-inflammatory agents might be able to reduce the risk of developing Alzheimer's disease. But a clinical trial of naproxen and celecoxib suggest this may not be so, for their use did not improve cognitive function in an at-risk group. Therefore, treatment with such drugs does not provide the hoped-for protection for the brain.

Introduction

Inflammation plays a role in many diseases, including Alzheimer's disease. Therefore, one might expect some protection from taking anti-inflammatory drugs, such as aspirin. Indeed, previous research has suggested that non-steroidal anti-inflammatory agents (NSAIDs, of which aspirin is one) does reduce the risk of Alzheimer's disease. Such chemoprevention is eagerly sought, for the incidence of Alzheimer's disease is going up as the population ages. However, not all studies have shown that NSAIDs have a protective effect. The ADAPT (Alzheimer's Disease Anti-inflammatory Prevention Trial) was set up to see what impact the NSAIDs naproxen and celecoxib have on the risk of Alzheimer's disease. The work was led by researchers at Johns Hopkins Bloomberg School of Public Health, Baltimore. This was the first trial to test the association of NSAIDs with the incidence of Alzheimer's disease and the change of cognitive function over time of people without previous impairment.

What was done

A group of 2,117 individuals with a family history of Alzheimer's disease, aged 70 or more, took either 200 milligrams of celecoxib twice a day, 200 milligrams of naproxen twice a day, or placebo twice a day. The trial lasted from March 2001 and December 2004 - and was then halted when information on the heart risk of celecoxib came to light. The individuals took tests relating to their cognitive function each year,

What was found

No improvement of cognitive functioning was found in the groups taking NSAIDs. Indeed, those on naproxen even did slightly worse than those in the other two groups.

What this study means

The findings conflict with some earlier research that suggest NSAIDs have a protective role to play against Alzheimer's disease. But they agree with other studies that showed no effect. The researchers say that the ADAPT findings might relate only to naproxen and celecoxib. Other NSAIDS, such as ibuprofen, might be protective. It may also be that NSAIDs need to be started earlier than they were in the ADAPT study. These participants may have had a sub-clinical form of dementia and it could have been too late to stop it progressing. Earlier, and more long-term, preventive treatment with NSAIDs may have more impact. Until we know more, neither naproxen nor celecoxib should be used for prevention of Alzheimer's disease, the researchers say.