A recent study suggests people who suffer from sleep apnea, a serious sleep condition where breathing starts and stops, are much more likely to develop dementia or Alzheimer’s disease.

In the study, older individuals whose sleep apnea was left untreated began to experience mental loss at an average age of 77, compared to those without breathing problems who saw decline in cognitive function at age 90.

The study did not establish cause and effect, but if sleep issues do lead to a decline in memory, it could be due to oxygen deprivation or fragmented sleep, according to the lead author of the study.

“I agree with the comments of the investigators who note there appears to be a potential link between sleep and dementia, but we can’t prove cause and effect,” said Dr. Charles Sherrill Jr. , an internist at Novant Health Sleep Center in Huntersville, North Carolina. “As I tell my patients, it’s not necessarily a lack of oxygen for one night that can affect you, but it could be the cumulative effect of a lack of oxygen nightly over years that could cause harm to the brain.”

An estimated 22 million people nationwide have sleep apnea, which could cause one to stop breathing at night and deprive the body of oxygen, according to the American Sleep Apnea Association.

Left untreated, it can lead to high blood pressure , heart disease, moodiness, memory problems and obesity – not to mention other effects of not getting a good night’s rest, such as lack of productivity and car accidents due to drowsiness.

“The most dangerous consequence of sleep apnea relates to the heart,” Sherrill said. “The intermittent, repetitive drop in oxygen levels in the blood over time can lead to heart problems and, as the present study suggests, brain injury. When patients arouse out of sleep, it creates a surge in blood pressure that is like being grabbed by the throat.”

Dementia is a general term when someone’s mental ability declines to the point where it interferes with day-to-day activities. Alzheimer’s, a common cause of dementia in older people, is an “irreversible, progressive brain disease that slowly destroys memory and thinking skills,” according to the National Institute on Aging. Symptoms of Alzheimer’s would typically appear in a person’s mid-60s, and the disease often makes it difficult to carry out simple tasks. An estimated 5 million Americans over age 65 have the disease.

The team of researchers at NYU Langone Medical Center conducted the study by evaluating the medical histories of individuals previously enrolled in an Alzheimer’s study. The participants indicated whether they had a diagnosis of sleep apnea and if they used continuous positive airway pressure therapy, or a breathing machine, while sleeping. The researchers focused on almost 2,500 people aged 55 to 90 and reevaluated them every six months.

There are three types of sleep apnea. The most common type is obstructive sleep apnea where the muscles in the back of the throat collapse, blocking the airway and affecting breathing.

One of the major symptoms is heavy snoring. It’s important to note snoring in combination with gasping, choking, snorting or pauses in breathing at night. Other symptoms include marked sleepiness throughout the day, fatigue, morning headaches, memory problems, depression, frequently waking up during the night to use the bathroom, and dry mouth or sore throat when you wake up in the morning.

Are you losing sleep at night? Read more about sleep apnea and how it’s diagnosed.