Many factors play a role in how fast the brain ages, including sleep quality, how fragmented sleep is, and how deep sleep is, UCSF researchers say.
Edwin Tan/Getty Images
People whose brains age faster than they do — as measured by an analysis of brain waves during sleep — are more likely to develop dementia later in life, according to a new study by UCSF researchers.
The study, published Thursday in JAMA Network Open, found that the greater the gap in someone’s “brain age” compared to their actual age, the more likely they were to develop dementia. The smaller the gap, the less likely they were to develop dementia.
Article continues below this ad
A 65-year-old with a brain age of 68, for instance, has a three-year gap.
“We found that gap is predictive of future risk of dementia,” said senior author Yue Leng, an associate professor of psychiatry at UCSF who studies the link between sleep and neurodegeneration.
For every 10-year increase in this gap, or “brain age index,” dementia risk rose by 39%, the study found.
San Francisco Chronicle Logo
Make us a Preferred Source to get more of our news when you search.
Add Preferred Source
Researchers determined study participants’ brain age index by using a machine-learning model to analyze sleep electroencephalography (EEG), which measures the brain’s electrical activity during sleep.
Article continues below this ad
The study analyzed data from about 7,100 U.S. adults aged 54 to 94 who enrolled in five different sleep studies. They did not have dementia at the start of the studies, and were followed for 3.5 to 17 years, depending on the design of the study they were in.
Many factors play a role in how fast the brain ages, including sleep quality, how fragmented sleep is, and how deep sleep is, Leng said.
“Those will contribute to brain age, and therefore the brain age gap,” Leng said.
Body mass index (BMI), cardiovascular risk factors and exercise may also affect sleep and brain aging.
Sleep researchers in general are still trying to figure out exactly how sleep impacts dementia risk. Many studies have shown that signs of poor sleep — such as sleep apnea, sleep fragmentation, increased daytime sleepiness and daytime napping — are linked to future risk of dementia. But it’s not yet clear whether the sleep problems themselves are causing the higher risk, or if the sleep problems are more of a marker.
Article continues below this ad
Some studies also suggest that sleep appears to help clear the buildup of Alzheimer’s-related proteins in the brain.
“There’s lots of evidence out there that shows sleep is not only about sleep itself, but also relates to your dementia risk,” Leng said.
Leng collaborated with Haoqi Sun, an assistant professor of neurology at Beth Israel Deaconess Medical Center in Boston, on the study. Sun helped develop the machine-learning model.
The takeaway for people, Leng said, is to pay attention to your sleep, which can be a window into your brain health. Note any sleep problems you may have, such as snoring or sleep apnea — which is under-diagnosed — and consider seeking medical care for them, she said.
Article continues below this ad
“Try to get good sleep, starting from treating sleep disorders you noticed,” she said. “Pay more attention to your sleep because it is important for your brain in general.”