PARIS: A simple brain-training exercise could reduce people’s risk of developing dementia by 25 per cent, a study said on Monday, but with outside researchers expressing caution in interpreting the results.

There are vast amounts of brain-training games and apps which claim to fight off cognitive decline, although there has been little high-quality, long-term research proving their effectiveness.

The new study is a randomised controlled trial — considered the gold standard for medical research — which first began enrolling participants in the late 1990s. More than 2,800 people aged 65 or older were randomly assigned one of three different types of brain training — speed, memory, or reasoning — or were part of a control group.

First, the participants did an hour-long training session twice a week for five weeks. One and three years later, they did four booster sessions. In total, there were fewer than 24 hours of training.

During follow-ups after five, 10 and most recently 20 years, the speed training was always “disproportionately beneficial”, study co-author Marilyn Albert of Johns Hopkins University in the United States said.

After two decades, Medicare records showed that the people who did the speed-training and booster sessions had a 25-pc reduced risk of getting dementia, according to the study. The other two types of training did not make a statistically significant difference.

“For the first time, this is a gold-standard study that’s given us an idea of what we can do to reduce risk for developing dementia,” Albert said.

However Rachel Richardson, a researcher at the Cochrane Collaboration not involved in the study, cautioned that “while statistically significant, the result may not be as impressive” as a 25-pc reduction.

This is partly because the margins of error “range from a reduction of 41pc to one of only five percent”, she told the Science Media Centre.

She added that the study excluded people with conditions such as poor vision or hearing, which meant it may not be fully representative. Baptiste Leurent, an expert in medical statistics at University College London, said the study had “important limitations”.

“Although one subgroup analysis produced a significant result, this single finding is not generally regarded as strong enough evidence to demonstrate the intervention’s effectiveness,” he said. “Further research is still needed to determine whether cognitive training can reduce the risk of dementia.”

‘Connectivity in the brain’

The speed training exercise involves clicking on cars and road signs that pop up in different areas of a computer screen. Albert said the researchers did not know why this particular exercise appeared to be more effective.

“We assume that this training affected something about connectivity in the brain,” she said. Discovering the exact mechanism for why speed training worked could help researchers develop a new, more effective exercise in the future, Albert said.

The results only applied to this specific exercise and cannot indicate anything meaningful about other brain-training games, she added.

But the finding was “extraordinarily important”, Albert emphasised, pointing out that reducing dementia among 25pc of the US population could save $100 billion in patient care.

Dementia affects 57 million people and is the seventh leading cause of death globally, according to the World Health Organisation. The study was published in the journal Alzheimer’s and Dementia: Translational Research & Clinical Research.

Published in Dawn, February 10th, 2026