According to the World Health Organization, dementia affects 57 million people and is the seventh leading cause of death globally.
A group of researchers recently reported that simple brain-training exercises can reduce the risk of dementia by 25%.
There are countless brain-training games and apps that claim to combat cognitive decline, although there is little long-term, high-quality research to prove their effectiveness.
This new study is a randomized controlled trial – considered the gold standard in medical research – that began recruiting participants in the late 1990s.
Over 2,800 people aged 65 and older were randomly assigned to one of three different types of brain training—speed, memory, or reasoning—or a control group.
First, participants underwent a one-hour training session, twice a week, for five weeks. One and three years later, they underwent four additional training sessions. In total, they received less than 24 hours of training.
In follow-up studies over 5, 10, and most recently 20 years, speed training consistently "provided superior benefits," said study co-author Professor Marilyn Albert of Johns Hopkins University in the US.
After two decades, the study's follow-up records show that participants who engaged in speed training and enhancement sessions had a 25% reduced risk of developing dementia.
The other two types of training showed no statistically significant difference.
"For the first time, this is a gold standard study that helps us better understand what we can do to reduce the risk of dementia," Professor Albert said.
However, Rachel Richardson, a researcher at the Cochrane Collaboration (a non-profit organization that collects and evaluates medical information) who was not involved in the study, cautioned that "while statistically significant, the results may not be as impressive as a 25% reduction."
This is partly due to the margin of error "ranging from a 41% decrease to just 5%," she said.
She also added that the study excluded people with vision or hearing problems, meaning it may not be entirely representative.
Baptiste Leurent, a medical statistics expert at University College London, UK, said the study has "significant limitations".
"Although a small-group analysis yielded statistically significant results, this single finding is generally not considered strong enough evidence to demonstrate the effectiveness of an intervention," he said.
"Further research is needed to determine whether cognitive training can reduce the risk of dementia."
"Connections in the brain"
The speed training exercise involves clicking on cars and traffic signs that appear in different areas of the computer screen.
Professor Albert said researchers don't know why this particular exercise seems to be more effective.
"We believe this training has had some impact on the connectivity within the brain," she said.
Professor Albert said that discovering the precise mechanisms behind why speed training is effective could help researchers develop a new, more effective exercise in the future.
According to her, this result only applies to this specific exercise and cannot show anything significant for other brain-training games. However, she also emphasized that the 25% figure is "extremely important."
If the incidence of dementia could be reduced by 25%, or the number of people suffering from it could be reduced by 25%, each country could save hundreds of billions of dollars in healthcare costs.