Smartwatch Study Finds Older Adults Can Sense Their Own Mental Decline in Real Time

Four times a day, for a week, a smartwatch on the wrist of an older adult buzzed with the same request: how sharp do you feel right now, and what is your mood? Once the answer was logged, the watch followed with a short test of processing speed and attention. That routine, repeated across 62 participants, is the core of a new University of California, Davis study that suggests older adults may be better judges of their own moment-to-moment mental sharpness than scientists once assumed.

The participants all performed within normal ranges on standard cognitive tests. The researchers compared each person against their own baseline. When someone rated their mental sharpness below their personal average, their score on the objective watch tasks also tended to be lower. Both the perceived sharpness and the measured performance tended to slip later in the day. The team accounted for age, mood and time of day. The work was published in Neuropsychology, a journal of the American Psychological Association.

What sets the study apart is where it measures. A traditional assessment captures one point in time, often in a quiet, controlled office. When patients raise concerns about their thinking, doctors typically depend on the patient's memory of past episodes, and may screen them on a day they feel fine. Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis, said researchers and doctors usually ask people to look back over the past year, and those answers are 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. Brandon Gavett, the study's first author, put the larger challenge plainly: "Measuring change in a person's cognitive functioning is really hard."

The finding that surprised Farias most concerned mood. Skepticism that people can judge their own cognition has a long history, partly because depression can color how people evaluate their memory, and earlier research has tied subjective cognitive concerns to depression. Yet in this study 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," Farias said.

Heather Snyder, senior vice president of medical and scientific relations at the Alzheimer's Association, was not involved in the research. She called the results 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 belongs to a growing body of work testing whether everyday technology can pick up subtle cognitive changes, with other researchers using wearables to look at speech and patterns of activity. In theory, a device could gather many observations while a person cooks dinner or runs errands, rather than a single snapshot in a clinic.

The approach has practical drawbacks. 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.

He was also direct about what the results cannot do. A week of smartwatch data will not tell anyone whether they are developing dementia. 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 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 next step, the researchers say, is continued testing in clinical trials, followed by larger populations, to establish how reliably such methods detect meaningful change. "Moving in the right direction to get people help for dementia as early as possible is the goal," Gavett said.