People with sleep apnea are more likely to suffer brain injury and disrupted memory and thinking, new research by the University of California, Los Angeles reveals.

Sleep apnea is caused by a blockage of the airways, usually when the tissue in the rear of the throat collapses and closes during sleep. Actually, the Greek word “apnea” literally means “without.” That’s why people with sleep apnea experience poor nights sleep.

According to the National Institutes of Health, sleep apnea is very common, affecting more than 12 million Americans. Risk factors include being male, overweight and over the age of 40, but sleep apnea can strike anyone at any age, even children. Worrisome is the fact that around 80 percent of men and 93 percent of women with sleep apnea are unaware they have this condition, despite the fact that it can have significant consequences.

Untreated sleep apnea can cause high blood pressure and other cardiovascular disease, weight gain, impotency and headaches.

Now, researchers at UCLA discovered that sleep apnea also causes tissue loss on brain regions that help store memory.

For the study, they used MRI to scan the brains of 43 sleep apnea patients, focusing on brain structures called mamillary bodies, located on the underside of the brain. They are called so because they resemble small breasts. The study found that the mamillary bodies of these patients were almost 20 percent smaller than those in 66 people without sleep apnea used as controls.

The findings are the more important as mamillary bodies are known to also shrink in patients who have other forms of memory loss related to alcoholism or Alzheimer’s disease.

The researchers don’t have a clear answer on what causes this shrink in sleep apnea patients, but they suspect that it is related to repeated drops in oxygen the brains suffer during an apnea episode causing cells to die. The same process is also linked to heart disease and stroke.

Lead researcher Ronald Harper, a distinguished professor of neurobiology at the David Geffen School of Medicine at UCLA concludes: “The reduced size of the mamillary bodies suggests that they’ve suffered a harmful event resulting in sizable cell loss. The fact that patients' memory problems continue despite treatment for their sleep disorder implies a long-lasting brain injury.”

The findings of the study will be published in the June 27 issue of Neuroscience Letters.