Older Adults Can Sense Their Own Mental Decline, Smartwatch Study Finds

Four times a day, for one week, a smartwatch on the wrist of an older adult buzzed with a simple request: how sharp do you feel right now? After the answer came a short test on the same watch, measuring how fast the person could process information and how well they could pay attention. That routine, repeated across 62 participants, is the heart of a new study from UC Davis.

The participants all scored within normal ranges on standard cognitive tests. The watches also asked them to rate their mood at each prompt. Researchers then accounted for age, mood and time of day. What emerged was a pattern: when a person rated their mental sharpness below their own personal 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 study was published in Neuropsychology, a journal of the American Psychological Association. Its approach is unusual because it captures thinking as it happens in daily life, rather than depending on someone's memory of how things have been or on a single test in a doctor's office. "Measuring change in a person's cognitive functioning is really hard," said Brandon Gavett, the study's first author.

The usual process has built-in weaknesses. When patients raise concerns about their thinking, doctors rely on recollections of past episodes, and they often screen patients at a time when they may be feeling better. Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis, said traditional assessments typically ask people to look back over the previous year, a method vulnerable to recall bias. Asking repeatedly about the present moment could sidestep some of that. "There's a lot of questions about how best to measure these complaints," she said.

There has also been long-standing doubt that people can judge their own cognition accurately, and mood is a large part of the reason. Depression can color how people assess their memory and abilities, and earlier research has tied subjective cognitive concerns to depression. Farias said one of the study's most encouraging findings was that the link between perceived sharpness and measured 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 work. 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," she said. Snyder added that the study joins a growing body of research on whether everyday technology could detect subtle cognitive changes, with other researchers using wearables to study changes in speech and patterns of activity.

The appeal is that measurement can leave the clinic. A conventional assessment captures performance at one moment, often in a quiet, controlled room. A wearable could in theory gather many observations while a person cooks dinner or runs errands. The approach has costs, though. Gavett noted that some older adults may not want to wear the devices or be prompted continuously, and that users must tolerate interruptions and remember to charge them.

The limits on what the findings mean are plain. A week of smartwatch data will not tell anyone whether they are developing dementia, Gavett said. Scientists still need to learn whether patterns gathered over months or years can predict later impairment. "Researchers may need to follow people for months or even years," he said, to see whether changes in these measures say anything meaningful about the risk of larger decline. Farias called that one of the biggest open questions.

The researchers' next step is to keep testing such approaches in clinical trials, then expand to larger populations and work out 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.