Fitness for your eyes and brain: A new approach to reducing dementia risk

For decades, older adults have been encouraged to keep their minds active through crossword puzzles, Sudoku, reading and memory exercises, based on the idea that mental stimulation helps protect the aging brain. New findings from the long-running ACTIVE study, however, suggest that the type of cognitive training may matter more than simply keeping the brain busy. The study followed 2,802 adults aged 65 and older who were assigned to memory training, reasoning training, speed-of-processing training or a control group. Researchers found that speed-of-processing training produced the most notable long-term results.

Earlier findings showed about a 29% lower risk of dementia after 10 years among participants who received this training compared with controls, while a 20-year follow-up found roughly a 25% lower rate of Alzheimer’s disease and related dementias among those who received speed training with booster sessions. The findings do not prove that a particular computer game can prevent Alzheimer’s disease, but they raise important questions about how targeted cognitive exercise may influence brain health.

Unlike traditional memory exercises, speed-of-processing training challenges people to identify information quickly while managing competing visual signals. One example, the Double Decision exercise, requires participants to identify a central object while simultaneously detecting another object in their peripheral vision. The difficulty increases as performance improves, creating a form of progressive cognitive overload similar to increasing resistance during physical exercise. This is particularly relevant to vision because the eyes and brain operate as a connected system rather than as separate organs.

The retina is neural tissue, while the optic nerve forms a direct pathway carrying visual information into the brain. Seeing clearly, therefore, does not necessarily mean that the brain is processing visual information efficiently. An older adult may maintain good visual acuity while becoming slower at detecting peripheral objects, shifting attention or responding to unexpected information. These abilities are especially important in everyday activities such as driving, where the brain must constantly process information from both the center and edges of the visual field.

Researchers and clinicians are increasingly interested in whether maintaining vision and cognitive processing together could contribute to healthier aging. Vision impairment has also been associated with increased dementia risk, although the relationship is complex and does not establish that poor vision directly causes Alzheimer’s disease. Reduced vision can lead to less physical activity, social isolation, reduced reading and fewer opportunities to interact with unfamiliar environments, potentially reducing cognitive stimulation.

The ACTIVE findings add another possibility: cognitive resilience may depend partly on how efficiently the brain processes the information it receives. The study’s use of adaptive training and booster sessions also suggests that cognitive fitness may require continued maintenance rather than a short period of mental exercise followed by years without practice. Still, dementia is influenced by numerous factors, including genetics, cardiovascular health, sleep, physical activity, hearing and social engagement. Cognitive training should therefore not be viewed as a guaranteed prevention strategy.

Instead, the research points toward a broader understanding of healthy aging—one that considers perception, attention and processing speed alongside memory. The emerging idea of “neurovisual fitness” could eventually encourage doctors to look beyond how clearly patients see and examine how efficiently their brains interpret and respond to visual information. The larger message is simple: keeping the brain active may not be enough; the kind of activity, the level of challenge and the need for continued practice may all matter.

As researchers continue to investigate the connection between vision, cognition and dementia, the eye could become more than a window into the brain—it could become an important part of understanding how the brain stays resilient with age.