Smartwatch Study Finds Older Adults Can Sense Their Own Mental Decline in Daily Life

Four times a day for a week, a smartwatch on the wrist of an older adult buzzed with the same request: rate how mentally sharp you feel, and how your mood is. Once the answers were logged, the watch offered a short test of processing speed and attention. That routine, repeated across 62 participants, is the backbone of a University of California, Davis study that suggests older adults may be better judges of their own moment-to-moment thinking than scientists once assumed.

All 62 participants performed within normal ranges on standard cognitive tests when they started. The researchers accounted for age, mood and time of day. What they found was that when a person rated their sharpness below their own average, their results on the objective tasks also tended to be lower. Both the ratings and the performance tended to slip later in the day. The work was published in Neuropsychology, a journal of the American Psychological Association.

The design is unusual because it captures cognition as people live it, rather than relying on memory or a single office visit. Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis, described the problem with the usual approach. Doctors and researchers typically ask someone to look back over the past year and assess how their thinking has been, and those assessments are vulnerable to recall bias. When patients do report cognitive trouble, clinicians depend on the patient's recollection and often screen them when they may be feeling better. Asking repeatedly about the present moment could sidestep some of those limits. "Measuring change in a person's cognitive functioning is really hard," said Brandon Gavett, the study's first author.

There is also a long-standing skepticism about whether people can judge their own cognition at all, and mood is a central complication. Previous research has found an association between subjective cognitive concerns and depression, and depression can itself make people feel their memory is worse. So Farias said the most encouraging result was that the link between perceived sharpness and actual performance did not appear to be explained by mood. "That's one of the aspects of the study that surprised me the most," she said.

Heather Snyder, senior vice president of medical and scientific relations at the Alzheimer's Association, was not involved in the research. She called it an interesting step toward learning whether people's perceptions could give researchers additional information about cognitive health. "Our perceptions are sometimes the first indicator," Snyder said. She noted the study joins a growing body of work testing whether everyday technology can pick up subtle cognitive change, including wearables that track changes in speech and in patterns of activity.

The appeal is that measurement can leave the clinic. A traditional assessment captures one point in time, often in a quiet, controlled room. A wearable could in theory gather many observations while someone cooks dinner, runs errands or goes about the day.

The limits are practical as well as scientific. Gavett said some older adults may not want to wear the devices or be continuously prompted, and users must tolerate interruptions and remember to charge them. He was also direct about what a week of data can and cannot do: it will not tell anyone whether they are developing dementia.

The open question is whether patterns gathered over months or years can predict later impairment. "Researchers may need to follow people for months or even years to determine whether changes in these measurements provide meaningful information about someone's risk of larger cognitive decline," Gavett said. Farias called that one of the biggest questions now facing the team. The researchers plan to keep testing such approaches in clinical trials before moving to larger populations and judging how reliably they detect meaningful change. "Moving in the right direction to get people help for dementia as early as possible is the goal," Gavett said.