The current JAMA has two articles on Alzheimer's disease that evaluate simple interventions, in hopes of maintaining age-appropriate cognitive functioning among two groups of older Americans. One study evaluated the efficacy of increasing seniors' physical activity to inhibit mental decline; the other evaluated omega-3 fatty acid plus vitamin supplementation for that same goal. Unfortunately, neither intervention showed any significant benefit.
In the first study, 1635 participants (ages 70-89) who undertook a 24-month physical activity program showed no difference in scores on two well-respected scales of intellectual/cognitive functioning. That's as compared with a control group that underwent only health education, reported Kaycee Sink, MD, of Wake Forest University in Winston-Salem, N.C., and colleagues from eight medical centers which participated in the LIFE (Lifestyle Interventions and Independence for Elders) study. Over the two-year course, 13 percent (98 patients) of the exercise group vs. 12 percent (91) in the control group developed incident Mild Cognitive Impairment (MCI) or dementia. Meaning, there was no real difference.
In the second study, which took five years with biannual checkups, 3,501 subjects (mean age 72) took either long-chain polyunsaturated (omega-3) fatty acids (LCPUFAs), or lutein plus zeaxanthin, or a placebo.
As reported by the AREDS2 (Age-Related Eye Disease Study-2) co-authors (led by Emily Chew, MD, of the National Eye Institute in Bethesda, Md.), "among older persons with age-related macular degeneration (AMD), oral supplementation with LCPUFAs or lutein/zeaxanthin had no statistically significant effect on cognitive function."
An editorial in the same journal, co-authored by Sudeep Gill, MD, and Dallas Seitz, MD, PhD, of Queen's University in Kingston, Ontario, Canada, pointed out that the findings from either of these studies should not be taken as a sign to ignore lifestyle factors when promoting health in older adults:
"Optimizing physical activity should be encouraged at every age--not just when symptoms of cognitive decline appear. Promoting a heart-healthy diet such as the Mediterranean diet is more apt to prevent cognitive decline or the onset of dementia than simply prescribing nutritional supplements later in life," the doctors wrote.
"Although these well-designed randomized controlled trials failed to demonstrate significant cognitive benefits, these results should not lead to nihilism involving lifestyle factors in older adults. There is clear evidence that physical activity and healthy diet contribute to improvements in a wide variety of health outcomes. However, it's likely the biggest gains in reducing the overall burden of dementia will be achieved through policy and public health initiatives promoting primary prevention of cognitive decline rather than efforts directed toward individuals who have already developed significant cognitive deficits."
To that, I would add that research on earlier diagnosis, years before clinical symptoms manifest, is currently underway in many labs and clinical trials. Pharmaceutical researchers are plugging away at this seemingly inexorable plague, and it is certain that such efforts will one day bear fruit, as it has for other "impossible" conditions (remember AIDS in the 1980s?). It's too bad simple interventions, as attempted by these two groups, failed to show promise.
