India, May 26 -- Sleep problems in older women may be more closely connected to Alzheimer's disease risk than previously understood.
A new study from researchers at the University of California San Diego has found that older women with a stronger genetic predisposition to Alzheimer's disease showed worse memory performance and greater buildup of abnormal tau protein in the brain when they also reported poor sleep quality (1).
The study was published in the Journal of Prevention of Alzheimer's Disease and was led by Kitty Lui and Dr Sarah Banks from the University of California San Diego School of Medicine.
Why Are Scientists Increasingly Worried About Sleep and Alzheimer's Disease?
For years, sleep problems were often viewed mainly as symptoms of aging. But scientists are now discovering that sleep may play a much bigger role in how the brain ages and how neurodegenerative diseases develop.
During deep sleep, the brain helps clear away toxic proteins and metabolic waste products that accumulate during waking hours. Scientists believe poor sleep may interfere with this cleaning process, allowing harmful proteins to build up gradually over time.
One of the most important proteins linked to Alzheimer's disease is tau.
Tau is a normal protein found inside brain cells. The new UC San Diego study focused specifically on tau buildup because researchers increasingly believe tau changes may begin many years before obvious dementia symptoms appear.
Scientists say sleep disturbances and Alzheimer's disease may create a dangerous cycle:
Poor sleep may promote abnormal protein buildup.
Protein buildup may damage brain regions that regulate sleep.
Worsening sleep may then further accelerate brain changes.
What Did the New Study Actually Find?
The new research examined 69 women aged 65 years and older who were participating in the ongoing Women Inflammation Tau Study (WITS) at the University of California San Diego.
The women completed questionnaires about their sleep quality. Researchers then evaluated their memory performance and performed advanced brain scans to measure tau protein accumulation.
To estimate genetic vulnerability to Alzheimer's disease, scientists used a tool called the Polygenic Hazard Score (PHS).
Women who had higher genetic risk for Alzheimer's disease and also reported poorer sleep showed the following:
Worse visual memory performance, and
Greater tau accumulation in important brain regions linked to early Alzheimer's disease.
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However, women with lower genetic risk did not show the same strong relationship between sleep complaints and brain changes.
Interestingly, the effect appeared specific to visual memory, which involves remembering shapes, locations, or visual patterns. The researchers did not observe the same association with verbal memory tasks.