Treating people who suffer from obstructive sleep apnea by administering continuous positive airway pressure can lower a person's risk of heart attack and stroke, a small study suggests.

Obstructive sleep apnea, or OSA, is a condition in which a person's airway is partially or completely blocked during sleep, leading to a lack of oxygen and frequent waking. According to the study, it occurs in nine per cent of middle-aged women and 24 per cent of men.

A CT scan of a brain following a stroke. Obstructive sleep apnea is associated with an increased risk of death from heart disease or stroke.
(CBC)

The condition is associated with an increased risk of death from heart disease or stroke.

"The majority of patients with OSA share several risk factors for atherosclerosis [the hardening of the arteries leading to heart disease], including obesity, hypertension, hypercholesterolemia, insulin resistance, and hyperglycemia," said T. Douglas Bradley and Dai Yumino, both of the Sleep Research Laboratory at the Toronto Rehabilitation Institute at the Centre for Sleep Medicine and Circadian Biology at the University of Toronto, in an editorial in the same issue of the journal.

The study, conducted by Brazilian researchers, is published in the October American Journal of Respiratory and Critical Care Medicine, the journal's first issue.

It involved 24 men with severe obstructive sleep apnea. In the study, participants' heart health was assessed over four months for indicators of atherosclerosis, arterial plaque levels, arterial stiffness, signs of inflammation, and catecholamine, a marker for physical stress.

After four months of continuous positive airway pressure therapy — which involves the pumping of air, usually through a person's nose or nose and mouth via a mask to keep the airway open — arterial plaque thickness declined by nine per cent. 

Researchers call the decrease "remarkable" given the fact that in a recent large-scale study, patients undergoing cholesterol-lowering pravastatin therapy saw their arterial plaque thickness decline by twelve percent after a full year.

Arterial stiffness also decreased, by 10.4 per cent.

"Our results demonstrate that four months of effective treatment with continuous positive airway pressure significantly improves validated markers of atherosclerosis in normosensitive middle-aged men with severe OSA," the report states.

The researchers caution that the lower levels of atherosclerosis in patients could be affected by the attitudes of study participants. They say this difference may be due to possible better overall adherence to all prescribed treatments in patients who accept the continuous positive airway pressure therapy than in those who do not, as opposed to any direct benefit that the therapy may offer.