Sleep apnea and lack of deep sleep linked to worse brain health

People who have sleep apnea and spend less time in deep sleep may be more likely to have brain biomarkers that have been linked to an increased risk of stroke, Alzheimer’s disease and cognitive decline, according to new research published online issue of Neurology.

The study looked at sleep factors and biomarkers of the health of the brain’s white matter. One of the biomarkers, white matter hyperintensities, are tiny lesions visible on brain scans. White matter hyperintensities become more common with age or with uncontrolled high blood pressure. The other biomarker measures the integrity of the axons, which form the nerve fibers that connect nerve cells.

The study involved 140 people with obstructive sleep apnea with an average age of 73 who had a brain scan and also an overnight study in a sleep lab. A total of 34% had mild, 32% had moderate and 34% had severe sleep apnea.

The sleep study examined how long people spent in slow-wave sleep, which is also called non-REM stage 3, or deep sleep, and is considered one of the best markers of sleep quality. The researchers found that for every 10-point decrease in the percentage of slow-wave sleep, there was an increase in the amount of white matter hyperintensities similar to the effect of being 2.3 years older. The same decrease was also associated with reduced axonal integrity similar to the effect of being three years older.

People with severe sleep apnea had a higher volume of white matter hyperintensities than those with mild or moderate sleep apnea. They also had reduced axonal integrity in the brain.

Reference:

Diego Z. Carvalho et al,AMERICAN ACADEMY OF NEUROLOGY,JOURNAL Neurology