Editor—In their study of the effect of non-steroidal anti-inflammatory drugs (NSAIDs) Etminan et al did not consider possible confounding factors for what is currently only an observed reduction in risk.1
What if having osteoarthritis is negatively associated with developing Alzheimer's disease? Presumably some form of osteoarthritis is the likely reason why older people are receiving NSAIDs. Both conditions have genetic and environmental components that may well be mutually exclusive.
That NSAIDs offer some protection against the development of Alzheimer's disease cannot yet be stated with confidence. As Davey Smith and Ebrahim pointed out in an editorial, an association does not show causation, and doctors have been caught out giving poorly based and premature advice (and treatment) before.2
A recently published randomised controlled trial did not show any benefit from either naproxen or rofecoxib in preventing the progression of early Alzheimer's disease.3 We may be no further forward in being able to prevent or treat this condition.
Competing interests: None declared.
References
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- 2.Davey Smith G, Ebrahim S. Data dredging, bias, or confounding. BMJ 2002;325: 1437-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Aisen PS, Schafer KA, Grundman M, Pfeiffer E, Sano M, Davis KL, et al. Effects of rofecoxib or naproxen vs placebo on Alzheimer disease progression: a randomized controlled trial. JAMA 2003;289: 2819-26. [DOI] [PubMed] [Google Scholar]