New York University School of Medicine, Rutgers School of Public Health
In this study, published in the journal Neurology, researchers at New York University School of Medicine and Rutgers School of Public Health found that sleep apnea can lead to mild cognitive impairment (MCI) nearly 10 years earlier than in those who don’t suffer from breathing problems during sleep. And those with sleep apnea were diagnosed with Alzheimer’s an average of five years earlier than those without sleep issues.
Sleep apnea is common in older adults, affecting more than half of all men and a quarter of all women. But many go undiagnosed until they are in a car accident because they are sleepy, they develop high blood pressure or they have a stroke.
People with sleep apnea have periods during the night when their throats close up and they briefly stop breathing. It is caused by a blockage of the airway, usually when the soft tissue in the back of the throat collapses during sleep and briefly closes the throat until the person partially awakens, gasping for air. Other symptoms are loud snoring, choking and snorting while sleeping. Breathing pauses can last from a few seconds to minutes and can happen as many as 300 to 400 times a night, but the person often doesn’t wake up enough to even be aware it is happening. Instead, they wake up in the morning feeling tired.
The team reviewed the medical histories of 2,470 people aged 55 to 90 who had participated in an earlier study designed to look for markers of Alzheimer’s disease. They found that sleep apnea was associated with a much quicker decline in cognitive function. But they also found that people who got treatment declined at the same speed as people who didn’t have apnea at all. Treatments can include machines that help people breathe better as they sleep (called CPAP devices), dental appliances (for mild cases) and weight loss.
Sleep apnea leads to drops in oxygen levels, which can affect various organs in the body differently and can damage parts of the brain. Dr. Andrew Varga, an Adjunct Instructor in Medicine at New York University and co-author of the study, noted that certain neurons in the hippocampus, where much of Alzheimer’s is thought to start, are very sensitive to drops in oxygen, and sleep apnea may stress out those neurons. Also, as mentioned earlier, the disrupted sleep may prevent the brain from cleaning out the amyloids that can turn into plaques.