Older Adults Can Sense Mental Decline in the Moment, UC Davis Smartwatch Study Finds

Four times a day, for one week, a smartwatch on the wrist of an older adult buzzed with the same request: rate how mentally sharp you feel right now, and how your mood is. Once the answer was logged, the watch moved straight to brief tests of attention and processing speed. That routine is the core of a UC Davis study published in Neuropsychology, a journal of the American Psychological Association.

The study gave smartwatches to 62 participants, all of whom had performed within normal ranges on standard cognitive tests. The question was whether their in-the-moment sense of their own thinking matched how they actually did. It largely did. When a person rated their sharpness below their own personal average, their performance on the objective tasks also tended to be lower. Researchers accounted for age, mood and time of day. Both perceived sharpness and measured performance tended to decline later in the day.

The design is unusual because it captures cognition as it happens, rather than depending on memory or a single office visit. Brandon Gavett, the study's first author, said measuring change in a person's cognitive functioning is really hard. Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis, said there are many open questions about how best to measure cognitive complaints.

The usual approach has drawbacks. When patients report cognitive trouble, doctors rely on their recollection of those episodes, and screening often happens when the person may be feeling better. Researchers and clinicians also commonly ask people to assess how their thinking has been over the past year, and Farias said such assessments are vulnerable to recall bias. Asking repeatedly about the present moment could sidestep some of that.

There is also a long-standing skepticism that people can judge their own cognition at all. Mood is a complication: earlier research has linked subjective cognitive concerns to depression, which can itself make people feel their memory is worse. Farias said one of the study's most encouraging findings was that the link between perceived sharpness and objective performance did not appear to be explained by mood. That, she said, was one of the aspects that surprised her most.

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

The appeal is measurement outside the clinic. A standard assessment captures performance at one point in time, often in a quiet, controlled room, while a wearable could in theory gather many observations as someone cooks dinner or runs errands. The tradeoffs are practical. 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.

The researchers are careful about what the results do not show. A week of smartwatch data cannot tell anyone whether they are developing dementia, Gavett said. Scientists still need to learn whether patterns gathered over months or years can predict later cognitive impairment, which would require following people for that long. Farias called that one of the biggest questions now facing the team.

The next step is to keep testing approaches like this one in clinical trials, then expand to larger populations and determine how reliably they can detect meaningful change. The goal, Gavett said, is moving in the right direction to get people help for dementia as early as possible.