For this study, researchers focused on verbal memory.

“Verbal memory is the ability to remember words in the appropriate context,” Bryce A. Mander, PhD, associate professor in the Department of Psychiatry and Human Behavior at the University of California, Irvine, and co-corresponding author of this study explained to Medical News Today.

“Remembering the names of streets at an intersection associated with a memory, or someone’s name, or how words are paired together are some examples of verbal memory.”

Mander and his team recruited 81 adults with an average age of about 62 and about 70% having a parental history of Alzheimer’s disease. The group was also 62% female participants.

All study participants participated in verbal memory assessments and polysomnography — a diagnostic tool for sleep disorders.

At the study’s conclusion, scientists found that sleep apnea events occurring during REM sleep negatively impact a person’s verbal memory, especially in participants with a genetic predisposition to or parental history of Alzheimer’s disease.

“We initially predicted events in non-rapid eye movement (NREM) sleep would be more predictive because there are specific brain waves that occur only during NREM sleep that support memory,” Mander said.

“However, we think these REM findings make sense because REM sleep also can support memory and it is a brain state that has a higher metabolic demand than NREM sleep and, in some memory-relevant brain areas, even higher than during wakefulness.”

“If you are starving your brain of oxygen during a brain state with higher metabolic demand, you may be more likely to get brain damage,” Mander added. “We think this is possibly the case and are examining this in our next studies.”

Mander said these findings underscore the impact that sleep apnea events can have when they occur during REM sleep.

“They have often been dismissed clinically, in favor of global sleep apnea metrics that have historically been poor at predicting cognitive and health outcomes,” he continued.

“These findings support the idea that looking at the brain state you experience sleep apnea in will offer a greater understanding of the cognitive consequences of sleep apnea.”

After reviewing this study, Adrian Pristas, MD, sleep medicine specialist and pulmonologist at Jersey Shore University Medical Center and corporate medical director of the Hackensack Meridian Centers For Sleep Medicine in New Jersey, told MNT that this research provides more understanding of the consequences of untreated sleep apnea — and any measure of poor sleep for that matter — on our health and specifically the adverse effects on cognitive well-being.

As more research is completed and shared, it is clear our brain suffers from OSA as well as short sleep,” Pristas continued.

“In general, the vast majority of adults with OSA are not identified and treated. There is a great opportunity for the medical community to positively change the trajectory for many of these patients.”

“The medical community, as well as the public, will need to accept the importance of all aspects of sleep health. This is an opportunity to make remarkable changes in population health. Specifically for those with Alzheimer’s disease, sleep testing must be part of the initial evaluation.”

— Adrian Pristas, MD, sleep medicine specialist, pulmonologist

MNT also spoke with Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA, about this study.

Segil said it was fascinating to read a study looking at certain types of problems sleeping to see if a breathing problem during the dreaming part of sleep or sleep apnea severity during REM sleep can cause problems with verbal memory.

“As the authors noted the underlying mechanism for their study’s observations remains unclear — it is also true why we dream and have REM sleep also remains unclear in 2024,” he continued.

“I was surprised to see gender and age alongside parental history and a genetic marker for dementia being evaluated as gender and age may not be accepted risk factors for dementia, while parental dementia history and ApoE4 status are accepted risk factors for dementia.”