While the report is disheartening, it is important to be clear about what it says. In reviewing the past studies that suggested certain options might help prevent or delay Alzheimer's or cognitive decline, it found that the supporting evidence did not meet its rigorous standards. Only in a relatively few instances did it find that the evidence showed a particular treatment would not work. Instead, it said only that the evidence for a purported link between the treatment and a reduction in the risk of dementia did not meet the rigorous standards set by the NIH "jury."
Here are some specifics to keep in mind:
- Factors such as eating a largely fruit-and-vegetable-and-whole-gain diet, physical exercise, and spending time with friends and family were found to be associated with a possible reduction in cognitive decline but with a low level of supporting evidence. These activities are likely good for the brain, but the jury didn't find enough evidence to say so definitively.
- Of the social factors, loss of a spouse showed real evidence of having an adverse impact.
- Of the dietary and nutritional studies, the jury found that the best supporting evidence was provided by the studies showing a link between fish consumption and reduced risk for cognitive decline.
- The study that came closest to clearing the "high degree of evidence" bar was a large trial of cognitive training (memory, reasoning and speed) that showed "modest benefits" on cognitive functioning and "a small, statistically significant effect on reducing age-related cognitive decline at a five-year follow-up.
- Some treatments were found not just to be based on weak evidence but to have failed the evidence test. The jury noted a recent large-scale test of ginkgo biloba, for example, that found it had no reduction in the incidence of Alzheimer's.
- As for prescribed medications, the jury found that "no known medication can be reliably said to delay the onset of Alzheimer's." And it noted that some studies, albeit somewhat flawed, showed a possible increased risk of Alzheimer's from taking the nonsteroidal anti-inflamatory drugs rofecoxib, naproxen and celecoxib. The jury also found that no preventive impact on cognitive decline had been found for statins, low-dose aspirin, or celecoxib, and that naxproxen was found to possibly increase cognitive decline.