Don't count on pills or supplements to save you from cognitive decline as you grow older.
Researchers at St. Michael's Hospital in Toronto conducted a review of the existing medical literature and concluded that there is no consistent evidence that drugs, herbal products or vitamin supplements can keep memory loss at bay. However, they found that mental exercises might be of some benefit.
As part of their review, they searched medical databases for high-quality studies and settled on 32 randomized controlled trials involving about 25,000 participants. "We wanted to keep it as broad as possible," said the lead researcher, Dr. Raza Naqvi, a fellow in geriatric medicine at the University of Toronto.
He noted that the members of the team included any therapy that has been suggested as a possible means of halting or slowing dementia. They did not find much reason for optimism.
For instance, they looked at two prescription medications used to treat patients diagnosed with dementia: donepezil (brand name Aricept) and memantine (Namenda). A handful of trials have tested these medications on healthy seniors, in the hopes that they might stop cognitive decline before it starts. "Our conclusion was that there was no delay in the onset of any memory-loss symptoms and no benefit in memory scores," Naqvi said.
Herbal and vitamin supplements did not fare any better. Studies of ginkgo, vitamin B6, omega-3 fatty acids and DHEA (dehydroepiandrosterone) – all products thought to help brain function – were of no use in preventing dementia.
But possibly the most disturbing finding was that a few treatments actually seem to contribute to cognitive problems. "Some of the therapies that are proposed to help prevent memory decline sometimes turn out be more harmful than beneficial," Naqvi said.
He pointed to a U.S. study, lasting a decade, that explored the use of estrogen in healthy women. "Rather than helping memory, the estrogen products worsened memory over time, when compared to subjects given a placebo," he said.
Anti-inflammatory medications – naproxen and celecoxib – also seem to make patients slightly worse, Naqvi said. "They were studied in over 2,500 patients over a three-year period and actually showed a marginal decline in memory scores."
Some experts have speculated that regular exercise could help stall memory loss by improving blood circulation to the brain. But the review found that the evidence supporting this theory is weak.
The only hopeful news came from studies involving mental exercises. But even in this area the optimism is guarded. Most of the research has focused on either computerize training programs or one-on-one teaching sessions, which are time-consuming and not usually available to the general public.
Commonly used mental exercises – such as crossword and Sudoku puzzles – have not been well studied as a way of maintaining cognitive health.
"The best evidence we have is that you have to keep your mind active in any way that is stimulating and beneficial to you," Naqvi said. "So that could be doing Sudoku and crossword puzzles and anything along those lines. Now that's not evidence-based, but I think it is the best we can do at this time."
Naqvi also advises his patients to remain physically active even though there is not yet convincing evidence that exercise can halt or slow memory loss. Physical activity has so many other health benefits that it is worthwhile doing, regardless of its effect on the mind, he said.
"Perhaps the most important application of this review can be the rebuttal of claims of many natural health-food products and other pharmacological agents that purport benefits to cognition," the researchers wrote in their study, published on Monday in the Canadian Medical Association Journal.
"If you are using over-the-counter or herbal products for the reason that you think it will help prevent memory loss, there is no strong evidence to support that sort of use," Naqvi said.