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

Four times a day for a week, a smartwatch on the wrist of an older adult buzzed with the same request: how sharp does your mind feel right now? The participant logged an answer, along with a rating of mood, and then took a brief test on the watch itself, one measuring processing speed and another measuring attention. That small routine sits at the center of a UC Davis study suggesting that older adults may judge their moment-to-moment mental sharpness better than scientists once assumed.

The study gave smartwatches to 62 participants, all of whom had performed within normal ranges on standard cognitive tests. The pattern the researchers found was consistent: when a person rated their sharpness below their own average, their performance on the objective tasks also tended to be lower. The researchers accounted for age, mood and time of day. Both perceived sharpness and measured performance tended to decline later in the day. The findings were published in Neuropsychology, a journal of the American Psychological Association.

The method is unusual in how it captures cognition. Doctors typically hear about memory complaints after the fact, and they often screen patients at a moment when the patient may be feeling better. Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis, said there are many open questions about how best to measure such complaints. Brandon Gavett, the study's first author, put the problem plainly: measuring change in a person's cognitive functioning is really hard.

The traditional approach asks someone to look back over the past year and assess how their thinking has been, Farias said, and those judgments can be skewed by recall bias. Asking repeatedly about the present moment could sidestep some of that. Gavett said the work offers a new way to build people's own sense of whether their cognition is better or worse than normal into the research.

There is also a long-standing skepticism about whether people can judge their own minds at all, and mood is the main complication. Depression can color how people evaluate their memory and cognitive abilities, and earlier research has linked subjective cognitive concerns with depression. For that reason, Farias said, one of the most encouraging results was that the link between perceived sharpness and objective performance did not appear to be explained by mood. She called it one of the aspects of the study 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 described the findings as 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 changes, with wearables also being used to study speech and patterns of activity.

The draw of such devices is that they work 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 collect many observations as a person cooks dinner or runs errands. The tradeoffs are practical, though. 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 study also has firm limits. A week of smartwatch data cannot tell anyone whether they are developing dementia, Gavett said. Researchers may need to follow people for months or even years to learn whether changes in these measurements say anything meaningful about the risk of larger decline, and Farias called that one of the biggest questions now facing the team. The next step is further testing in clinical trials, followed by larger populations, to see how reliably the approach detects meaningful cognitive change.