By Kathleen Doheny
Men with undiagnosed, severe obstructive sleep apnea (OSA) had more than double the risk of depression compared to those without sleep apnea, said study researcher Carol Lang, a research fellow in the department of medicine at the University of Adelaide in Australia.
Lang said she can't explain why these conditions seem to be linked. "Many of the symptoms of OSA and depression overlap, such as tiredness, fatigue, daytime sleepiness, low vitality and poor concentration," she said. The two conditions also share some common risk factors, such as advancing age.
While the nature of the study prevents "our drawing any conclusion to cause and effect," Lang said, she added that the relationship between apnea and depression was strong.
Lang was scheduled to present the findings at the American Thoracic Society meeting on Monday in Denver. Studies presented at medical meetings are considered preliminary until published in a peer-reviewed journal.
Lang evaluated nearly 860 men for the study. Their ages ranged from 35 to 83, and the average age was 60. During the five-year study period, the men were evaluated twice for depression. They underwent sleep lab studies to see if they had obstructive sleep apnea.
People with sleep apnea experience periods when their breathing becomes very shallow due to partial blockage of the airway, Lang said. They may even stop breathing for 10 seconds or longer. Sometimes it happens over a hundred times a night, she said.
In the new study, the researchers defined severe apnea in the conventional way, using a score known as the apnea hypopnea index (AHI) that measures how often someone has shallow breathing or pauses in breathing per hour. Those with an AHI score of 30 or greater were classified as having severe sleep apnea.
Lang said it's not clear if the study's findings would also apply to women as they weren't included in the current research. But she said women have more depression than men, and that women with obstructive sleep apnea have been shown to have more severe depression symptoms. She and her team are planning a study on sleep apnea and depression in women.
About 18 million Americans have obstructive sleep apnea, according to the National Sleep Foundation. Treatment for the disorder generally involves wearing a mask that provides continuous positive airway pressure (CPAP) to keep airways open during sleep. However, the study authors noted that in a previous study, CPAP didn't seem to help ease symptoms of depression in people with sleep apnea.
Lang's study findings echo some earlier research, said Dr. Alan Manevitz, a clinical psychiatrist at Lenox Hill Hospital in New York City. He cited one study -- published in 2012 -- in which men and women with sleep apnea and symptoms of snorting or paused breathing at least five nights a week were three times more likely to show signs of major depression compared to those who didn't have apnea symptoms.
The new findings, he said, are "just confirming what other studies have done." According to Manevitz, "the interplay between sleep and mood has always been present. Depression may cause sleep problems and sleep problems may cause or contribute to depression."
The take-home point is clear, he said. "Whichever diagnosis you may have, you should get screened for the other diagnosis," Manevitz said.
For people with sleep apnea, simply being aware of the link between the sleep problem and depression can help, Lang said. Talk to your doctor if you have concerns, she said.
He said he also tells patients to avoid alcohol and sleeping pills, as both make the airway more likely to collapse.
Sleeping on your side can help reduce apnea, too, Manevitz said. If you need to, he suggested putting a tennis ball in the back of your night shirt to keep you on your side.