A Simple Brain Exercise Could Cut Your Dementia Risk in Half—20 Years Later

A modest five-to-six-week cognitive training program focused on processing speed, combined with booster sessions years later, was linked to a 25% lower risk of dementia diagnosis over the next 20 years. The finding comes from the longest-running study of its kind and suggests that a relatively simple, non-pharmaceutical intervention could have lasting protective effects on brain health as we age.

What Type of Brain Training Actually Works?

Researchers from the University of Pennsylvania, Johns Hopkins Medicine, and other institutions analyzed data from 2,021 older adults who participated in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study, which began in 1998–1999. The study tested three different types of cognitive training to see which, if any, could reduce the risk of Alzheimer's disease and related dementias (ADRD) over time.

The three training approaches tested were:

• Speed of Processing Training: Participants learned to quickly locate visual information on a computer screen and handle increasingly complex tasks in shorter time periods, adapting to their individual performance level.
• Memory Training: Focused on teaching strategies to improve recall and retention of information.
• Reasoning Training: Designed to help participants solve problems and understand relationships between concepts.

Each training arm involved up to 10 sessions of 60-to-75-minute training spread over five to six weeks. The critical difference came next: half of the participants who completed at least eight sessions were randomly assigned to receive booster training sessions at 11 and 35 months after the initial training ended.

Which Training Showed Real Results After 20 Years?

When researchers reviewed Medicare claims data spanning from 1999 to 2019, the results were striking—but only for one type of training. Among participants in the speed-training group who received booster sessions, 40% were diagnosed with dementia over the 20-year follow-up period, compared to 49% in the control group who received no training. This represented a 25% reduction in dementia incidence.

The hazard ratio for speed-trained participants with boosters was 0.75, meaning they had about a 25% lower risk of developing diagnosed Alzheimer's disease and related dementias. However, speed-trained participants who did not receive booster sessions showed no significant protection, with a hazard ratio of 1.01—essentially the same risk as the control group.

Surprisingly, neither memory training nor reasoning training showed a statistically significant effect on dementia risk, even with booster sessions. This finding was unexpected and raises important questions about why speed training stood out.

Why Does Speed Training Work When Other Brain Exercises Don't?

Researchers believe the answer lies in how the brain learns and adapts. Speed training was adaptive, meaning it automatically adjusted the difficulty level based on each person's performance that day. People who were faster at the start moved to faster challenges quickly, while those who needed more time started at slower levels. In contrast, memory and reasoning training used the same strategies for everyone in the group.

Another key difference involves the type of learning. Speed training relies on implicit learning—the kind of unconscious, automatic learning that builds habits and skills, similar to learning to ride a bike. Memory and reasoning training, by contrast, rely on explicit learning—consciously learning facts and strategies. Scientists already know that implicit and explicit learning work very differently in the brain, and this distinction may explain why speed training had lasting protective effects decades later.

"Seeing that boosted speed training was linked to lower dementia risk two decades later is remarkable because it suggests that a fairly modest nonpharmacological intervention can have long-term effects," said Marilyn Albert, Ph.D., director of the Alzheimer's Disease Research Center at Johns Hopkins Medicine. "Even small delays in the onset of dementia may have a large impact on public health and help reduce rising health care costs."

What Do These Findings Mean for Dementia Prevention?

The study involved 2,021 participants (72% of the original 2,802 enrolled), with an average age of 74 at the start of follow-up. About three-fourths of participants were women, 70% were white, and during the 20-year period, approximately three-fourths of participants died at an average age of 84. Despite this high mortality rate, researchers were able to track dementia diagnoses through Medicare records.

Dementia affects an estimated 42% of adults older than age 55 at some point in their lives and costs the United States more than $600 billion annually. Alzheimer's disease accounts for 60% to 80% of dementia cases, while vascular dementia accounts for 5% to 10%, with other types including Lewy body and frontotemporal dementia.

The booster sessions appear to be crucial. Participants who completed the initial speed training but skipped the booster sessions showed no significant dementia protection. This suggests that maintaining cognitive engagement over time—not just a single intervention—may be what drives long-term brain health benefits.

Researchers note that speed training may work synergistically with other lifestyle interventions that strengthen neural connections, though more research is needed to understand these interactions. Other activities associated with reduced cognitive decline risk include supporting cardiovascular health through monitoring blood pressure, blood sugar, cholesterol, and body weight, as well as engaging in regular physical activity.

"Our findings provide support for the development and refinement of cognitive training interventions for older adults, particularly those that target visual processing and divided attention abilities," explains George Rebok, a lifespan developmental psychologist and professor emeritus of mental health at the Johns Hopkins Bloomberg School of Public Health. "It is possible that adding this cognitive training to lifestyle change interventions may delay dementia onset, but that remains to be studied."

While these results are encouraging, researchers emphasize that additional studies are needed to understand the underlying mechanisms and to determine why reasoning and memory interventions didn't show the same long-term associations. The ACTIVE study remains the largest investigation in the United States of different types of cognitive training in older adults, making this 20-year follow-up particularly valuable for understanding how brain health interventions can have lasting effects.