A sleep disorder that interrupts breathing can raise women’s risk of dying from heart attacks and having other cardiovascular problems in much the same way as it does for men.
What’s more, obstructive sleep apnea is also linked with sudden hearing loss, particularly in men.
These are recent findings of two independent studies, the first one by researchers from Spain, and the second from a new study in Taiwan.
But treating severe apnea at night with a mask and breathing device called continuous positive airway pressure, or CPAP, can also help reduce the risk of heart attack deaths in women with apnea—just as it can in men, the Spanish researchers report.
The breathing of people who suffer from apnea is repeatedly interrupted during sleep. The airways close for short intervals during sleep, leading to repeated drops in blood oxygen levels and frequent short waking, along with snoring and daytime sleepiness.
The sleep disorder affects more men than women, but up to three percent of middle-aged women have it. Until now, not much research has focused on sleep apnea in women. Aside from CPAP, weight loss is the most effective treatment.
“Women with untreated severe obstructive sleep apnea have a three-and-a-half-fold increase in the risk of dying from cardiovascular disease compared to women without (it),” says researcher Dr. Francisco Campos-Rodriguez, Seville’s Valme University Hospital’s sleep-disordered breathing unit director. He led the Spanish researchers who published their work in the Annals of Internal Medicine Jan. 17 issue.
Meanwhile, Taiwanese researchers from several universities in that island pored over medical records in a large health insurance database and found that patients who’d suffered sudden deafness were more likely to have a previous diagnosis of sleep apnea than those without hearing loss.
The absolute difference was small: 1.7 percent of those with hearing loss had sleep apnea, compared to 1.2 percent without hearing trouble.
“Male patients with sudden hearing loss had a higher proportion of prior obstructive sleep apnea than men who didn’t have sudden hearing loss; no such association was found among female patients,” Dr. Jau-Jiuan Sheu of Taipei Medical University Hospital and his colleagues write in the Archives of Otolaryngology-Head & Neck Surgery.
“Further study will be needed to confirm our findings, explore the underlying pathomechanisms, and investigate the difference between sexes,” they note.
Dr. Seva Polotsky, a sleep apnea researcher from Johns Hopkins University School of Medicine in Baltimore, Maryland, agrees. For now, “There are more questions than answers, ” he says. The doctor wasn’t wasn’t involved in the new study,
“Obviously we don’t know from this paper whether treating apnea will reduce hearing loss,” or the chance of having hearing problems in the first place.
But “if there is sudden hearing loss, I would investigate the presence of apnea as well, given that it’s easy to diagnose and it’s easy to treat,” he tells Reuters Health.
Dr. Polotsky surmises that sleep apnea, because it increases the buildup of plaque in blood vessels, could affect vessels in the brain areas that control hearing, or vessels that feed the nerves responsible for hearing.
Most complications associated with sleep apnea, like high blood pressure and diabetes, are thought to result from frequent oxygen fluctuations during the night—and sudden hearing loss could fit into that category, he says.
On the Spanish study, Dr. Campos-Rodriguez says his team “provided the first evidence in the (medical) literature that severe OSA is associated with cardiovascular mortality in women, and that CPAP treatment is associated with a decrease in mortality risk.”
But more research will be needed to find out what could be behind this link, he cautions, because the study is observational. Researchers can’t say if it was the apnea that caused the increased rates of death or if it was the CPAP that reduced that risk.
In Spain, researchers identified 1,116 middle-aged women sent to sleep medicine clinics in Spain for suspected apnea.
Researchers determined who among the patients really had the sleep disorder; those not found to have the condition functioned as the control group. They then measured the severity of the apnea and divided the patients into “mild-to-moderate” or “severe” groups. Some in each group received CPAP treatment and some did not.
After observing the patients in all groups for 88 months or over seven years, researchers found that 41 patients—about four percent—had died of cardiovascular problems and three percent of other causes.
Of these 41 deaths from cardiovascular disease, 18 were in the group with severe and untreated apnea, while eight were from the group with severe but treated apnea.
Women who were treated with CPAP had lower cardiovascular disease death rates similar to those without apnea. In contrast, deaths from cardiovascular problems were more frequent in women who had apnea that wasn’t treated, especially when it was severe.
The Taiwanese researchers, meanwhile, examined the health records of one million Taiwanese and found almost 3,200 had been diagnosed with sudden deafness between 2000 and 2008. For each of those people, they picked out another five of the same age and sex without hearing loss to serve as a comparison, Reuters reports.
Out of those 19,000 people, 240 had been diagnosed with sleep apnea before the episode of sudden deafness occurred.
Researchers then factored in obesity, heart disease and other health and lifestyle issues and found that men with sudden deafness were 48 percent more likely to have a previous sleep apnea diagnosis than men without hearing loss. The association for women was less clear, researchers say.
The new findings don’t mean that sleep apnea causes sudden hearing loss. For one, researchers couldn’t account for people’s smoking and drinking—factors that may affect the risk of both conditions.
But the Taiwanese researchers theorize that inflammation and changes in blood vessels linked to sleep apnea could contribute to the risk for deafness. Tinnitus, the sensation of ringing in the ears, has been linked to circulatory disorders, for example, they note.
But the current study, Polotsky said, “doesn’t really establish that. It just shows us a new potential area to research.”
There are about 4,000 new cases of sudden deafness each year in the United States according to the National Institutes of Health. There are more than 100 possible causes of sudden deafness, and it’s rare for a specific cause to be precisely identified. Only 10 percent to 15 percent of patients with sudden deafness know what caused their hearing loss. Possible causes include the following: Infectious diseases, trauma and head injury, abnormal tissue growth, immunologic diseases such as Cogan’s syndrome, toxic causes, such as snake bites, ototoxic drugs (drugs that harm the ear), circulatory problems, neurologic causes such as multiple sclerosis, relation to disorders such as Ménière’s disease.
In general, the deafness only occurs in one ear, and most people regain their hearing over a period of weeks, sometimes aided by steroid treatment. Sometimes, though, the hearing loss becomes more serious.