Older adults can accurately judge how mentally sharp they are during everyday activities, according to a new study from UC Davis Health. Using smartwatch-based assessments, researchers found that participants' own ratings of their cognitive sharpness closely matched their actual performance on objective cognitive tests.
The findings suggest that real-time self-assessments could become a valuable tool for identifying subtle cognitive changes and potentially detecting early signs of cognitive decline or Alzheimer's disease sooner than conventional clinic-based evaluations. "Our goal is to understand how people perceive their cognition, or ability to think, and how that compares with how they actually perform using objective test measures," said senior author Sarah Tomaszewski Farias, professor in the Department of Neurology at UC Davis Health, director of the UC Davis California Alzheimer's Center of Excellence and clinical core leader of the UC Davis Alzheimer's Disease Research Center. "We found that people's moment-to-moment impressions of their cognitive abilities were closely aligned with their actual performance. This could help lead to earlier detection of cognitive decline and Alzheimer's risk than standard cognitive testing," she added.
Smartwatch captures cognition in daily life
The study included 162 older adults with an average age of approximately 72 years. Although all participants had concerns about memory or cognitive changes, they had previously performed within the normal range on standard cognitive assessments. For one week, participants received prompts on an Apple Watch four times each day. They were asked to rate their current mental sharpness as well as their mood, including feelings of stress, fatigue and depression. They also completed brief cognitive tasks on the smartwatch that measured attention and processing speed.
Unlike traditional assessments, which often rely on patients recalling symptoms over weeks or months, this approach measured cognition while participants went about their normal daily routines. This methodology, known as ecological momentary assessment, allowed researchers to capture cognition in real-world settings rather than controlled clinical environments.
"When the participants were performing cognitive tests and rating their mental sharpness, it was happening throughout their day, whether they were doing chores at home or out shopping," Tomaszewski Farias explained. "We were capturing their cognition in real time, rather than having them come into a clinic where it's very quiet and in a very artificial, contrived environment."
Mood had little influence
The researchers compared participants' subjective ratings of mental sharpness with their objective cognitive performance throughout the week. They also examined whether emotional factors influenced people's ability to judge their own cognitive functioning. The analysis showed a clear relationship between perceived and measured cognition. Whenever participants rated their mental sharpness as lower than their own average, they also performed worse on the cognitive tests. This association remained significant regardless of age, mood or other contextual factors.
Because subjective cognitive complaints are often linked to depression, the researchers expected mood to influence self-assessments. Instead, they found that mood had little effect on the relationship between perceived and actual cognitive performance. "It was exciting to find that mood didn't play a big role in the relationship between how they felt, how sharp they felt and how they performed on the cognitive test," Tomaszewski Farias said. "This suggests that measuring subjective cognition in the moment may be more sensitive to objective cognitive performance, and less affected by depression than when measured in the clinic or laboratory."
Supporting earlier intervention
The study also identified a daily pattern in cognitive performance. Participants generally performed better earlier in the day, supporting current clinical advice that cognitively demanding activities are often best scheduled during the morning. According to the researchers, real-time subjective assessments could give clinicians a more accurate picture of how patients function outside the clinic, where daily circumstances and routines influence cognition. Rather than relying solely on periodic clinical testing or retrospective questionnaires, wearable technology may provide continuous insight into subtle cognitive changes as they occur.
If validated in larger and longer-term studies, this approach could help clinicians identify individuals at increased risk of cognitive decline earlier and provide more personalised support for people who notice changes in their thinking during everyday life.
Using smartphones
Recently, researchers from the German Centre for Neurodegenerative Diseases (DZNE) have shown that smartphone- and tablet-based memory tests can detect subtle cognitive decline earlier than traditional neuropsychological assessments. The study followed 202 adults aged 52 to 85, including 50 with mild cognitive impairment (MCI), who completed memory tests at home every two weeks using the neotivTrials app. Frequent digital assessments enabled researchers to identify cognitive decline within a few months, compared with the much longer timeframe required by conventional testing.
The app's results closely matched clinical data collected over an average of eight years, demonstrating the reliability of digital cognitive biomarkers. According to the researchers, this approach could accelerate dementia drug development by providing faster insights into disease progression and may eventually support routine clinical care through convenient, home-based monitoring.
