Obstructive sleep apnea occurs when the throat muscles relax during sleep, blocking the airway. That leads to repeatedly waking up to breathe. Sleep apnea leads to lower levels of oxygen while a person sleeps. That can damage small blood vessels in the brain. That damage is significant enough to be seen by an MRI. It causes structural changes in the area of the brain responsible for memory formation.
Co-corresponding author Michael Yassa, a professor at UC Irvine, said, “We may have found a missing piece of the puzzle. Low oxygen during REM sleep seems to harm tiny blood vessels in the brain, and that damage shows up in areas we rely on for memory. This might help explain why even mild sleep apnea can impact brain health long before memory problems show up.”
The study used 37 people, 24 of whom had obstructive sleep apnea. Their average age was 73, and they did not have cognitive problems. The research included overnight sleep and brain imaging.
The study showed that lower levels of oxygen, not the number of times a person stopped breathing and their sleep was interrupted, impacted the brain the most. People are often diagnosed with “mild” sleep apnea if it isn’t bad enough to wake them up. However, the continued oxygen deprivation — even if it isn’t enough to startle someone awake — can cause serious harm. The two factors that most clearly predicted vascular damage were how low oxygen levels dropped at their lowest and the total time spent below 90 percent blood oxygen.
The damage to the blood vessels was also linked to negative changes in an area of the brain affected early in Alzheimer’s. People with these changes had poorer memory retention overnight. While more research is needed, this study suggests that untreated sleep apnea could raise the risk of Alzheimer’s.
Many people don’t know they have sleep apnea. It becomes more common as we age. There are warning signs you can discuss with your doctor. A partner may know if you ever stop breathing in your sleep. Loud snoring can be a symptom. If you wake up tired despite getting enough sleep, you should talk to a doctor. CPAP machines are a standard treatment that can help you get a better night’s sleep and may protect your brain health.
