NEW YORK (Reuters Health) – A recent prospective study disproves earlier observations that non-steroidal anti-inflammatory drugs (NSAIDS) prevent Alzheimer dementia (AD). At best, NSAIDS may delay its onset, according to the report in the April 22nd online issue of Neurology.

“The NSAIDs-AD relationship has been evaluated in more than 30 observational studies. Most have confirmed the original observations” of a prophylactic effect of NSAIDS, the authors write, “although some well-designed studies have found different results.”

In the prospective Adult Changes in Thought (ACT) study, Dr. John C.S. Breitner, of the University of Washington School of Medicine in Seattle, and colleagues analyzed NSAID use and development of dementia or AD in 2,736 members of a large local health care plan who were dementia-free at enrollment.

Strengths of the study included “an electronic pharmacy dispensing database with prescription information available since 1977 and a large sample that enabled unusually detailed analyses,” the researchers note. Screening and exams for dementia started in 1994, with biennial follow-ups continuing for as long as 12 years.

Using pharmacy records, the investigators identified 351 subjects (12.8%) with a history of heavy NSAID use at enrollment and an additional 107 who became heavy users during follow-up. Incident dementia developed in 476 subjects, including 356 with AD. The median age at onset of either dementia or AD was roughly 83 years.

“Contrary to the hypothesis that NSAIDs protect against AD, pharmacy-defined heavy NSAID users showed increased incidence of dementia and AD, with adjusted hazard ratios of 1.66 and 1.57,” the researchers report. Patient-reported NSAID use did not affect the results, they add.

The authors believe their findings are “a truer representation of the association of NSAIDs and dementia risk” than results from earlier studies, not only because they used a community-based sample but also because of their regular assessments for dementia and AD, access to “rigorous exposure classification based on pharmacy dispensing records” dating back 17 or more years before enrollment, inclusion of self-reported exposure data as well as pharmacy reports, and large numbers of incident dementia or AD cases “affording good statistical power.”

They explain that the observational results found elsewhere may reflect delayed onset of AD in NSAID users. “Conceivably, such delay could result in increased AD incidence in late old age.” Indeed Dr. Breitner pointed out in a press release from the publishers of the journal that “our participants were older.”

If NSAIDS do delay the onset of AD, he added, “It would follow that studies looking at younger people who use NSAIDs would show fewer cases of Alzheimer’s, while in groups of older people there might be more cases, including those that would have occurred earlier if they had not been delayed.”

Nonetheless, Dr. Breitner concluded, “We must not ignore the fundamental finding, which is an increase in the risk of dementia in the NSAID users. We need further research to understand that result more clearly.”

Reference:
Neurology 2009.