Cognitive ‘speed training’ can reduce the risk of a dementia diagnosis by 25%, according to a groundbreaking randomized controlled trial. This study is the first of its kind to assess the effectiveness of an intervention for dementia.

“Skepticism surrounded brain training interventions for years, but this study provides clear evidence of their benefits,” says Marilyn Albert from the Johns Hopkins University School of Medicine.

The brain training sector has faced controversy, especially after companies overstated claims about cognitive decline prevention. In 2014, around 70 scientists signed an open letter stating no conclusive evidence existed that brain training leads to significant real-world changes or enhances brain health, echoing sentiments later supported by another letter signed by over 100 scientists.

Now, a comprehensive 20-year study with 2,832 participants aged 65 and older indicates that specific cognitive exercises may yield tangible benefits.

Participants were divided into three intervention groups and a control group. One group underwent speed training with a computer task called “Double Decision,” where cars and road signs briefly appeared, challenging participants to recall details after they disappeared. This adaptive task increases in complexity as users improve.

The other two groups focused on memory and reasoning training aimed at enhancing cognitive skills.

Each group completed two sessions per week for five weeks, with about half receiving booster sessions and additional training at one-year and three-year intervals.

After twenty years, evaluations of U.S. Medicare claims revealed that participants who completed speed training with booster sessions had a 25% lower risk of an Alzheimer’s diagnosis or related dementias than those in the control group. Other groups without boosters showed negligible changes in risk, which Albert describes as “truly amazing.”

“The study’s rigorous methodology is commendable,” notes Torkel Klingberg from Karolinska Institutet, Stockholm. “The impressive 20-year follow-up and the significant reduction in dementia risk are crucial findings.”

However, Walter Boot from Weill Cornell Medical College cautions that measuring numerous outcomes over two decades can lead to coincidental findings. “While the results may suggest significance, they should be interpreted cautiously,” he adds.

The mechanism behind the effectiveness of speed training is still being explored. One theory suggests it relies on implicit learning, which can entail long-lasting changes without conscious effort, according to Albert.

Etienne de Villers Sidani from McGill University explains that brief, intense experiences can lead to significant, enduring changes in the brain—much like how a traumatic event can instill lasting fears.

This training may enhance the brain’s cognitive reserve, a potential buffer against cognitive decline. Albert notes that enhanced brain connectivity could improve attention division, facilitating daily activities and fostering physical activity and social engagement—key factors for sustained brain health.

The authors propose that results from the booster sessions suggest a dose-dependent effect of speed training. Bobby Stoyanowski from the Ontario Institute of Technology emphasizes the need for future research into optimal training levels: “What is the right amount of training to maximize benefits?”

In summary, Andrew Budson from Boston University advises against isolating oneself to play speed training games endlessly. Instead, engaging in activities that promote implicit learning—like learning new skills or sports—may provide long-term cognitive benefits while being enjoyable.