Along with the projected increase in the number of elderly people over the next few decades, we can also expect an increase in the ailments that bedevil them — and few are as concerning as Alzheimer's Disease and other forms of dementia. According to the US Census, in 2014 about 15 percent of the US population was 65 years old or older. That percentage is expected to reach about 24 percent by 2060 and as the population grows so will the number of people in that age group.
Several types of actions that people can take to prevent or delay dementia have been touted, primarily as a result of epidemiological studies. These include regular exercise, prescription medications, cognitive training (e.g. word games, memory training), and OTC vitamins and supplements. But how effective are such aids? A group of researchers from the University of Minnesota and Brown University examined the scientific literature related to these supposed beneficial factors. They performed meta-analyses of data related to each and published them in separate reports in the Annals of Internal Medicine.
With respect to each type:
Physical exercise: Sixteen trials were included, with various types of exercise interventions compared to inactive controls. Participants had no signs of dementia at the initiation of the studies, and follow-up lasted from 6 months to 1 year. The evidence was "insufficient to draw conclusions about the effectiveness of aerobic training, resistance training or tai chi for improving cognition." There was weak evidence that an intervention that included several modalities could delay cognitive impairment.
Prescription medications: There were 51 trials of a large variety of drugs included in the study. Effects of the treatments on cognitive functioning were compared to placebo controls or standard care. Included trials examined diabetes medications, non-steroidal anti-inflammatory drugs, hormones (e.g. estrogen and estrogen-progesterone), lipid-lowering drugs, and dementia medications. None prevented cognitive impairment.
Cognitive Training: In all, eleven trials of at least 6 months duration were included. Five of them had participants with mild cognitive impairment (MCI) at the beginning of the study, while those in the other 6 trials did not. In the group with no MCI, training improved cognitive ability—but just in the modality trained, i.e. memory training improved memory only. Training didn’t improve performance in the group with MCI. There was no robust evidence that training prevented the onset or delayed the progression of dementia.
OTC Supplements: There were 38 trials in this study; they examined possible effects of a variety of supplements on the prevention or progression of dementia, compared to controls. Supplements examined included omega-3 fatty acids, vitamin C, vitamin B12 plus folate, beta-carotene, soy, ginkgo biloba and combination supplements. Improvements in performance on some memory tests were found with daily folate-B12, but there were no other supplements that provided a statistically or clinically significant result.
Thus the results of these systemic reviews are disappointing with respect to the prevention or delay of age-associated dementia. It’s certainly possible that beginning treatments earlier or continuing them longer than was done in these studies could produce more positive results. But certainly none of the examined treatments turned out to be any sort of a “magic bullet” for Alzheimer’s Disease or other dementia.