New Study Links Severe Sleep Apnea During REM to Decline in Verbal Memory

Around 936 million adults globally live with obstructive sleep apnea (OSA) — a condition where a person has interruptions, or pauses, in breathing when sleeping, causing disrupted sleep. Past studies have linked OSA to a heightened risk for several neurological conditions, including cognitive decline, dementia, Parkinson’s disease, and Alzheimer’s disease. 

Now, researchers from the University of California, Irvine have found that sleep apnea severity during the rapid eye movement (REM) stage of sleep negatively impacts verbal memory, especially in older adults at a high risk for Alzheimer’s disease. 

The study was recently published in the journal Alzheimer’s Research & Therapy. Verbal memory is the ability to remember words in the appropriate context and is particularly vulnerable to Alzheimer’s disease and is one of the earliest forms of memory to be impacted by Alzheimer’s disease biomarkers. Researchers studied this form of memory because of its vulnerability to decline with aging and Alzheimer’s disease. Researchers 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 which is a diagnostic tool for sleep disorders. 

Researchers 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. 

If a person is starving their brain of oxygen during a brain state with higher metabolic demand, they may be more likely to get brain damage. Researchers think this is possibly the case and are examining this in their next studies. After reviewing this study some doctors said that this research provides more understanding of the consequences of untreated sleep apnea and any measure of poor sleep for that matter on human health and specifically the adverse effects on cognitive well-being. 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.