A landmark 20-year study involving more than 2,000 adults aged 65 and older has found that a specific type of brain training could reduce dementia risk by up to 25 percent.

With projections showing that nearly two million people could be living with dementia by 2050, the findings offer a promising new approach to prevention.

According to Professor Marilyn Albert, a neurobiologist at the and lead author of the study, the research represents a major scientific milestone.

She described it as “the first gold-standard evidence showing that targeted brain training may help reduce dementia risk.”

Dementia, defined by the World Health Organization (WHO)as a syndrome that affects memory, thinking, and daily functioning, remains one of the most pressing global health challenges, particularly among aging populations.

Speed-Based Brain Training Shows the Strongest Results

Participants in the study were randomly assigned to one of three cognitive training groups or a control group. Each intervention involved hour-long training sessions twice a week for five weeks.

One group completed a speed-of-processing exercise called “Double Decision,” a computer-based task designed to improve attention and visual processing speed.

Participants briefly viewed a car and a road sign before they disappeared and were asked to recall their positions.

As participants improved, the task became progressively more difficult, adding distractors and increasing complexity to stimulate broader brain engagement.

The other groups focused on:

• Memory training, which strengthened verbal recall

• Reasoning training, which enhanced problem-solving skills

Crucially, about half of the participants later received booster sessions—additional training sessions conducted one year and three years later.

After two decades, researchers discovered a striking result: participants who completed speed training along with booster sessions had a 25 percent lower risk of developing dementia compared to the control group.

Notably, participants who did speed training without booster sessions did not experience the same protective benefit.

Professor Albert described the results as “astonishing,” suggesting that repeated cognitive stimulation over time may strengthen neural pathways and improve the brain’s resilience against decline.

Despite the promising findings, researchers emphasized that the study has limitations.

Nearly half of the control group developed dementia, which aligns with real-world rates but raises questions about participant selection and generalizability.

Dr. Baptiste Leurent, professor of medical statistics at University College London (UCL), expressed caution, noting that the strongest result came from a subgroup analysis rather than the primary randomized comparison. He described the evidence as“encouraging but not definitive.”

Similarly, Dr. Susan Kohlhaas of welcomed the long-term research but emphasized that the study does not conclusively prove brain training can prevent dementia, as diagnoses were based on health records rather than direct clinical assessments.

Experts agree that brain training should complement, not replace, proven dementia prevention strategies, including:

• Regular physical activity

• Managing cardiovascular health

• Maintaining social engagement

• Supporting lifelong learning

Dementia Remains a Growing Global Health Crisis

Dementia is an umbrella term for progressive neurological disorders that impair memory, thinking, and behavior. The most common form is Alzheimer’s disease, according to the World Health Organization (WHO).

Globally, dementia rates are rising rapidly due to aging populations. In the UK alone, over 900,000 people currently live with dementia, a number projected to reach 1.4 million by 2040.

In the United States, approximately 5.5 million people are affected, and cases are expected to increase significantly in coming decades.

While there is currently no cure for dementia, new treatments can slow progression, especially when the condition is detected early.

The findings from this 20-year study offer hope that targeted cognitive training—particularly speed-based brain exercises repeated over time—may become an important tool in reducing dementia risk.

However, researchers emphasize that further studies are needed to confirm the findings and determine how best to apply brain training in real-world prevention strategies.