When an older adult tells a doctor their memory has worsened over the past six months, that report often does not align with their cognitive test scores. Researchers at UC Davis Health tried a different approach and got a different result.
Instead of asking people to summarize months of experience in a clinic, they gave 162 older adults Apple Watches and prompted them four times a day for a week to rate how sharp their thinking felt at that moment. Participants also completed brief tasks measuring processing speed and attention on the watch at those same moments.
The self-ratings matched the test performance. The findings, published in the journal Neuropsychology, suggest that the way a question is asked may matter as much as what is asked.
One detail shapes how far the result travels. Every participant had concerns about memory or cognitive changes, yet all scored within normal limits on standard cognitive tests before the study began. This was not a general sample of older adults.
Timing Changed the Answer
The method is called ecological momentary assessment, and the distinction from standard testing is timing rather than content.
Retrospective self-report asks a person to average an experience across weeks, filter it through mood, and compress it into a single answer. Momentary self-report asks only about now. Senior author Sarah Tomaszewski Farias, a neuropsychologist at UC Davis Health and director of the UC Davis California Alzheimer's Center of Excellence, said that clinic-based testing, when paired with retrospective questions, frequently yields results that do not correlate with how people describe their own memory problems.
Ratings in this study were collected while participants went about ordinary activities, such as doing chores at home or shopping, rather than sitting in a quiet exam room that the researchers described as an artificial environment.
When participants rated their sharpness below their personal average, their test scores were lower as well, independent of mood, age, and context. Mood did not weaken the link between perceived and measured cognition, which the researchers noted is meaningful because low mood is a known confounder that can make people underrate cognition they are performing adequately.
Thinking Was Sharper Earlier in the Day
A secondary finding may be the most immediately usable. Participants showed sharper thinking earlier in the day.
Tomaszewski Farias said clinicians often already advise patients to "do things that are more cognitively demanding earlier in the day," and said the study potentially supports such recommendations.
For an older adult managing medications, finances or complex paperwork, that is a scheduling suggestion rather than a treatment. Moving a demanding task to the morning costs nothing and risks nothing.
Families supporting a relative with early cognitive changes can apply the same logic to important conversations, medical appointments, and care decisions. Scheduling those in a person's stronger window is a small adjustment with a plausible payoff.
None of this constitutes a clinical recommendation, and time-of-day effects vary among individuals. The finding describes a group average across 162 people with an average age of about 72.
The Limits Deserve Equal Billing
This was an observational study measuring the relationship between two variables at the same time points. It did not test whether momentary assessment detects cognitive decline earlier than existing methods, nor did it follow participants long enough to determine who later developed dementia.
Researchers have suggested the approach could eventually support earlier detection of cognitive decline and Alzheimer's risk. That is a hypothesis this study motivates rather than a conclusion it establishes. Demonstrating earlier detection would require following participants over years and comparing outcomes against standard assessment, the kind of longitudinal work carried out at centers such as the UC Davis Alzheimer's Disease Research Center.
The sample of 162 participants is reasonable for this kind of intensive protocol but modest for generalizing. The published report does not establish how well findings apply across different racial, ethnic, educational, and socioeconomic groups, and cognitive testing has well-documented performance differences across those lines.
There is also no validated consumer product that does this. The smartwatch protocol here was a research tool with a specific testing schedule, not an app anyone can download. Commercial brain training and memory apps are not equivalent and are not what this study evaluated.
The work involved collaborators at Washington State University and the University of California, Merced, alongside the UC Davis team, and was funded by the National Institutes of Health. It was distributed through research news channels at the end of June. Independent replication is the usual next checkpoint for a methodological finding like this one.
The Practical Takeaway for Families Right Now
Anyone worried about their own memory or a relative's should still see a clinician. This study does not change diagnostic pathways, and self-assessment of any kind is not a substitute for evaluation.
What it does offer is a reason to take momentary reports seriously. If an older adult says their thinking feels foggy today, that report may carry more information than a general statement about the past several months. Noting when the fogginess happens, what was going on, and how often it recurs gives a clinician something more specific to work with than a summary impression.
Keeping a simple written log for a few weeks before an appointment is a reasonable step. Time of day, sleep the night before, medications taken, and what the person was trying to do all provide context that a single clinic visit cannot capture.
People with concerns about cognition can ask a primary care clinician for a referral to a neurologist, geriatrician, or neuropsychologist. Memory disorder centers affiliated with academic medical centers often accept referrals, and the Alzheimer's Association helpline can help families locate local evaluation resources.
Further research using this method with larger and more diverse groups would move the finding from an interesting measurement result to something that changes how cognition is assessed.
Key Questions Answered
What did the researchers do? They gave 162 older adults Apple Watches and prompted them four times a day for a week to rate how sharp their thinking felt. Participants also completed brief tests of processing speed and attention at those moments.
What did they find? Momentary self-ratings of mental sharpness closely matched objective cognitive test performance, unlike retrospective self-reports collected in clinic settings.
Who were the participants? Older adults with an average age of about 72 who had concerns about memory or cognitive changes but scored within normal limits on standard cognitive tests before the study.
Why would timing change the accuracy? Retrospective reports require averaging weeks of experience and can be shaped by mood. In this study, mood did not weaken the link between perceived sharpness and measured performance.
What was the finding about time of day? Participants showed sharper thinking earlier in the day, which the senior author said potentially supports existing clinical advice to schedule demanding tasks in the morning.
Does this detect Alzheimer's earlier? Not as demonstrated. Researchers have suggested it could support earlier detection, but this study did not follow participants over time or compare detection against standard methods.
Is there an app that does this? No. The protocol was a research tool with a specific testing schedule. Commercial brain training and memory apps were not evaluated in this study and are not equivalent.
