Central OC Times

A study led by the University of California, Irvine (UC Irvine) has discovered a link between the frequency of sleep apnea events during the rapid-eye-movement (REM) stage and the severity of verbal memory impairment in older adults at risk for Alzheimer’s disease. The findings, recently published online in Alzheimer’s Research & Therapy, have opened doors to personalized interventions.

Verbal memory refers to the cognitive ability to retain and recall information presented through spoken words or written text. This faculty is particularly vulnerable to Alzheimer's disease. The research found a specific correlation between the severity of sleep apnea – a condition characterized by pauses in breathing during sleep – and diminished cognition. Higher ratios during REM compared to non-REM stages were associated with worse memory performance.

“Our findings identified the specific features of sleep apnea that are associated with memory, which is important because clinically, events occurring during REM sleep are often overlooked or minimized,” said co-corresponding author Bryce Mander, UC Irvine associate professor of psychiatry & human behavior. He added that current evaluation standards may lead to misdiagnosis and undertreatment as they do not focus on sleep-stage-specific apnea severity.

Ruth Benca, professor and chair of psychiatry and behavioral medicine at Wake Forest University School of Medicine, who was also a co-corresponding author, noted that women are more likely than men to have a greater proportion of their apneic events in REM sleep. This could potentially contribute to their higher risk for Alzheimer’s disease.

The study involved 81 middle-aged and older adults from the Wisconsin Alzheimer’s Disease Research Center with heightened risk factors for Alzheimer's disease. Of these participants, 62 percent were female. They underwent polysomnography – a comprehensive test that records various physiological functions during sleep – and verbal memory assessments. Results showed apnea events during REM to be a critical factor contributing to verbal memory decline, especially among individuals with a genetic predisposition to Alzheimer’s and those with a parental history of the disease.

“Our findings highlight the intricate relationship among sleep apnea, memory function and Alzheimer’s risk,” Mander said. “Identifying and addressing REM-specific events are crucial for developing proactive, personalized approaches to assessment and treatment that are tailored to individual sleep patterns.”

The research team also included lead author Kitty K. Lui, a graduate student in the San Diego State University/University of California, San Diego joint doctoral program in clinical psychology, as well as faculty and graduate students from UC Irvine, UC San Diego, the Wisconsin Alzheimer’s Disease Research Center and the University of Kentucky.

This work was supported by several grants from the National Institute on Aging, the National Institutes of Health’s Ruth L. Kirschstein National Research Service Award, and the National Center for Advancing Translational Sciences’ Clinical and Translational Science Awards Program.