March 30, 2012

Risk Of Depression Heightened By Sleep Disorder

A new study by researchers at the U.S. Centers for Disease Control and Prevention (CDC) found that people suffering from a common form of sleep disorder are also increasing their risk of depression, reports Health.com.

In the new research, men who are diagnosed with sleep apnea have been found to be more than twice as likely as other men to show signs of clinical depression. And researchers saw a bigger risk when looking at the link in women with sleep apnea: a fivefold risk increase of depression.

And this is only scratching the surface. CDC researchers believe that more than 80 percent of the people suffer some form of sleep apnea go undiagnosed, passing off symptoms as normal sleeping habits, which tend to include snorting or gasping for air during sleep. This group of people had a threefold risk of depression over those who had no trouble sleeping at night.

Carl Boethel, MD, a sleep specialist at Texas A&M Health Science Center College of Medicine, who was not involved in the research, said sleep apnea is way underdiagnosed. “Physicians in the sleep community and in the psychiatric community need to do a better job of screening and getting effective treatment,” he remarked.

Sleep apnea is a dangerous sleep disorder that, if gone untreated, can lead to other serious health problems such as diabetes, stroke, high blood pressure and congestive heart failure, as well as depression and anxiety. The causes of sleep apnea are attributed to oversized tonsils, airway structure, and excess fat around the windpipe, often due to overall obesity.

Because sleep apnea is often associated with obesity, the CDC scientists took into account body mass index in their analysis.

The study, appearing in the April issue of the journal SLEEP, is the first of its kind to look at a representative cross-section of the U.S. population. Data was taken from the National Health and Nutrition Examination Survey (NHANES), an annual survey conducted by the CDC.

Researchers found that 6 percent of men and 3 percent of women had received a sleep apnea diagnosis. They further found that 7 percent of men and 4 percent of women who had not received a diagnosis for sleep apnea had also reported breathing problems on at least 5 nights per week.

The team assessed depression using a standard questionnaire that asked participants how often in the past two weeks had they felt “little interest or pleasure in doing things” or had feelings of depression or hopelessness. The researchers found that five percent of men and eight percent of women had scores indicating “probable” depression.

Michael Weissberg, MD, co-director of the insomnia and sleep disorders clinic at the University of Colorado School of Medicine, in Denver, said one of the most complicating factors of the effects of sleep apnea and depression is the fact that it can be difficult to distinguish between them.

“There probably is an important connection between depression and sleep apnea, but it's hard to sort out who has what,” Weissberg told Health.com. “Sleep disruption, particularly insomnia, can be a risk factor for developing depression, and a lot of symptoms of people who have sleep apnea -- they feel lousy, they can't think straight -- are similar to symptoms people have in depression.”

The CDC said their study only offered an association and not cause and effect. They said they could not rule out the possibility that some other unknown factor may contribute to both sleep apnea and depression. However, they said it is plausible to think that sleep apnea could directly cause depression.

Lead author on the work, Anne Wheaton, PhD, an epidemiologist at the CDC, said previous research has shown a link between sleep apnea and mood swings. And the momentary drop in oxygen levels a person gets during an apnea could lead to changes in the brain by triggering stress or inflammation.

“Interrupted sleep may be associated with problems as far as what's going on in the brain,” Wheaton says. “You need that steady sleep.”

One factor the CDC researchers ruled out affecting depression risk was snoring not attributed to sleep apnea. More than a third of men and 1 in 5 women who reported snoring at least five nights per week were no more likely to be depressed than those who never snored.


On the Net: