A simple, targeted brain-training exercise may significantly reduce the risk of developing dementia, according to a long-running scientific study. Researchers found that older adults who regularly practised a specific speed-based cognitive exercise had a 25 per cent lower risk of dementia over 20 years. While the findings are promising, experts stress that more research is needed before drawing firm conclusions.
The research, considered a gold-standard randomized controlled trial, began in the late 1990s and followed more than 2,800 adults aged 65 and older. Participants were randomly assigned to one of three cognitive training types—speed, memory, or reasoning—or to a control group with no training.
The total training time was modest. Participants completed hour-long sessions twice a week for five weeks, followed by short booster sessions one and three years later. In total, the training was less than 24 hours over several years.
During follow-ups after five, 10, and 20 years, one form of training consistently stood out: speed-based cognitive exercises. According to a study co-author at Johns Hopkins University, participants who completed speed training and booster sessions were significantly less likely to develop dementia, based on Medicare health records.
The other two types of training, focused on memory and reasoning, did not show statistically meaningful benefits.
“This is the first time a study of this quality has given us a real sense of what might reduce dementia risk,” said one of the researchers involved.
The speed exercise involved a computer-based task where users clicked on objects—such as cars or road signs—that appeared quickly in different areas of a screen. The goal was to improve reaction time and visual processing speed.
Researchers are not certain why this approach worked better than others, but they believe it may influence brain connectivity and strengthen neural pathways linked to attention and processing.
Despite the encouraging headline figure, independent experts urge restraint in interpreting the results. Researchers from the Cochrane Collaboration noted that the statistical range of benefit varied widely, from as much as a 41 percent reduction to as little as five percent.
Others noted that the study excluded individuals with poor vision or hearing, so the findings may not apply to all older adults. A medical statistics expert from University College London emphasized that one significant subgroup result alone is not enough to prove effectiveness.
In short, while the findings are intriguing, they are not yet conclusive.
Researchers stress that the results apply only to this specific speed-training exercise and should not be generalized to the many commercial brain-training apps currently on the market. There is still no strong evidence that most brain games can prevent cognitive decline.
However, if future research confirms these findings, the impact could be substantial. Dementia currently affects 57 million people worldwide and is the seventh leading cause of death, according to the World Health Organization. Even a modest reduction in risk could translate into enormous social and economic benefits.
The study was published in Alzheimer’s & Dementia: Translational Research & Clinical Research, and researchers agree that more trials are needed to understand why speed training works and whether improved versions could be developed.
For now, the findings offer cautious optimism: certain forms of mental exercise may help protect brain health, but they are not a cure or a substitute for broader dementia prevention strategies such as physical activity, social engagement, and cardiovascular health management.
