A new study suggests that none of the current treatments believed to help prevent or delay dementia, actually make much of a difference.

After a careful review of published evidence, researchers conclude that there is as yet no intervention that will prevent dementia. The findings are published in Annals of Internal Medicine. Researchers studied available evidence for physical activity, prescribed medications, over-the-counter vitamins and supplements, and cognitive training interventions in patients who did not have dementia.

In their editorial accompanying the papers the authors state “of the papers cited in the 4 reviews, the vast majority did not meet strength-of-evidence standards, offered little evidence of effectiveness, or both.”

A small minority of study results suggested potential benefits of interventions: Group cognitive training improved performance only in the cognitive domain trained (e.g. memory training improved memory performance), but did not improve any other aspects of cognition. One of several studies that combined different types of interventions (physical activity, diet and cognitive training) improved cognitive test performance.

The failure of these interventions to show benefit on cognition may be because these interventions don’t improve cognition. However, at least in part it also could be because studies started the interventions too late in life, didn’t use them long enough, or because of shortcomings in many of the studies.

It is possible that practicing a healthy lifestyle earlier in life (regular physical activity, control of vascular risk factors, healthy diet, engaging in cognitively stimulating activities) may help to prevent or delay late life dementia, though this has not been proven or even directly tested. Nevertheless, such lifestyle changes are unlikely to worsen cognition and may have other, noncognitive benefits.