People can sense mental decline, says new research powered by smartwatches

A UC Davis study published in the American Psychological Association journal Neuropsychology found that older adults' real-time self-ratings of mental sharpness correlate with their objective cognitive performance, suggesting people can sense moment-to-moment cognitive decline. The study, which used smartwatches with 62 participants over one week, found that when participants rated their mental sharpness below their own average, their performance on cognitive tasks also tended to be lower, and this relationship was not explained by mood. The findings could help develop earlier detection of cognitive changes, including those preceding dementia.

Getting your Trinity Audio //trinityaudio.ai player ready...Older adults may be better judges of their moment-to-moment mental sharpness than scientists once assumed, according to a UC Davis study — which relied on familiar technology: the smartwatch. The study found that when an individual rated their mental sharpness below their own average, their performance on the objective cognitive tasks also tended to be lower. Published in the American Psychological Association journal Neuropsychology , the findings could eventually help researchers develop new ways to identify cognitive changes https://www.mercurynews.com/2025/07/28/you-can-slow-cognitive-decline-as-you-age-large-study-finds-heres-how/ earlier, potentially including those that precede dementia https://www.mercurynews.com/2026/05/05/alzheimers-deaths-increase-as-population-ages-lifespans-increase/ . It is unusual because it captures cognition during daily life rather than relying on a person’s memory or a single office test using the ubiquitous mobile technology. “Measuring change in a person’s cognitive functioning is really hard,” said Brandon Gavett, the study’s first author. The real-time approach is innovative. When patients report cognitive issues, doctors rely on their memory of those events and screen them when they may be feeling better. “There’s a lot of questions about how best to measure these complaints,” said Sarah Tomaszewski Farias, a study author and professor of neurology at UC Davis. The study gave smartwatches to 62 participants who performed within normal ranges on standard cognitive tests. Four times a day for one week, the participants received a reminder on the watches to rate their mental sharpness and mood. After participants logged their perceptions, they completed brief tests on the watches measuring processing speed and attention. Researchers accounted for factors including age, mood and time of day. Both perceived mental sharpness and cognitive performance tended to decline later in the day. The findings, Gavett said, offer a new way to incorporate people’s own perceptions of whether their cognition is better or worse than normal. Traditionally, researchers and doctors ask someone to retrospectively assess how their cognition has been over the past year, Farias said. Those assessments can be affected by recall bias. Asking people repeatedly how they feel in the moment could get around some of those limitations. Historically, there has also been skepticism that people can judge their own cognition. Mood, for example, is a complication. Depression can influence how people evaluate their memory and cognitive abilities. But Farias said one of the study’s most encouraging findings was that the relationship between participants’ perceived mental sharpness and their objective 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. That’s because previous research has found an association between subjective cognitive concerns and depression https://www.mercurynews.com/2026/07/09/older-adults-fear-becoming-a-burden-more-than-death-survey-finds/ , she said, and depression itself can make people feel that their memory is worse. Heather Snyder, senior vice president of medical and scientific relations at the Alzheimer’s Association, who was not involved in the study, called the findings an interesting step toward understanding whether people’s perceptions could provide researchers with additional information about cognitive health. “Our perceptions are sometimes the first indicator,” Snyder said. Snyder said the study joins a growing body of research exploring whether everyday technology like smartwatches could help scientists detect subtle cognitive changes. Researchers are using wearables to study changes in speech and people’s patterns of activity, as well, she said. The appeal of mobile technology is that it allows measurements outside of a clinic. A traditional cognitive assessment captures how someone performs at a particular point in time, often in a quiet and controlled environment. A wearable device could theoretically collect many observations as a person cooks dinner, runs errands or goes about the rest of their day. But a smartwatch that buzzes several times a day comes with its own limitations. “Some older adults may not want to wear the devices or be continuously prompted,” Gavett said. He added that users have to tolerate interruptions and remember to charge them. People should know, however, that a week of smartwatch data isn’t going to tell someone whether they are developing dementia, he said. Scientists still need to determine whether patterns collected over months or years can predict future cognitive 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 said that is now one of the biggest questions facing the researchers. The researchers say the next step will be to continue testing approaches like this in clinical trials before expanding to larger populations and determining how reliably they can detect meaningful cognitive changes. “Moving in the right direction to get people help for dementia as early as possible is the goal,” Gavett said.