OSA symptoms often go untreated in older adults
When taking stock of risk factors for stroke, sleep might not be one of the first things to enter your mind. But abnormal sleepmore specifically, a disorder called sleep apneais associated with high blood pressure and abnormal heart rhythms (arrhythmias) that can raise your risk of stroke.
The National Heart, Lung, and Blood Institute estimates that more than 12 million American adults have sleep apnea, and most aren't diagnosed or treated. The condition becomes more common as you get olderat least one in 10 people older than 65 has sleep apnea. Are you at risk? You might be if you are overweight or obese or if you snore loudly. High blood pressure, decreased airway size and a family history of apnea also are risk factors.
Types of sleep apnea
Sleep apnea most often occurs when the muscles that normally keep the throat open and allow air to enter the lungs temporarily relax or collapsea condition called obstructive sleep apnea. When this happens, little or no air enters the lungs, interrupting breathing for 10 seconds or longer. Less often, sleep apnea results from a disruption in the brain center that controls breathing. This is called central sleep apnea.
If you have either type of sleep apnea, the breathing interruptions that occur throughout the night (hundreds of times in some people) lower oxygen levels in your blood. Quality of sleep is affected as well. Each breathing interruption causes you to drift back and forth between deep sleep and light sleep. As a result, you won't feel rested or refreshed in the morning.
Central sleep apnea may be particularly troublesome for adults over 70. A 2011 study found that the risk of ischemic stroke increased with the severity of central sleep apnea in people in this age group. The researchers also found that central sleep apnea could be a marker of silent brain ischemia (insufficient blood flow), which in itself could account for the breathing disturbances. The study results, published in the journal Acta Neurologica Scandinavica, found that in these older adults, central sleep apnea, versus the obstructive type, was related to a higher risk of ischemic stroke.
Do you have sleep apnea?
Most people affected by sleep apnea don't know they have the condition, because the symptoms are often subtle. Symptoms of obstructive sleep apnea and central sleep apnea can be similar. They include:
- sleepiness throughout day
- morning headaches
- memory or learning problems
- irritability and mood swings
- inability to concentrate
- dry throat upon waking
- frequent nighttime urination
Most often, however, a bed partner recognizes the condition first, because of such hard-to-miss symptoms as loud snoring, choking and gasping during sleep or stopped breathing. If you (or your sleep partner) suspect sleep apnea, speak to your doctor. He or she will perform a medical history and a physical examination (focusing on your mouth, nose and throat to identify any abnormalities that may decrease airway size). Don't forget to bring along your sleep partner; he or she can provide valuable information to your doctor about your symptoms.
If the medical history and physical exam suggest sleep apnea, your doctor might recommend a sleep study to confirm the diagnosis. The study is performed overnight in a sleep laboratory, usually at a hospital or sleep disorders clinic.
While you are sleeping in the laboratory, a device called a polysomnogram (PSG) painlessly records your brain activity, eye movement, muscle activity, breathing, heart rate, amount of air that moves into your lungs, and oxygen concentration in your blood. In some cases, doctors may suggest using a portable sleep monitor at home.
A diagnosis is made based largely on two factors: cessation of airflow (apnea) and
reduced airflow (hypopnea), indicated by a decrease in oxygen levels in the blood. The average number of apnea-hypopnea episodes per hour is known as the apnea-hypopnea index (AHI). In adults, a diagnosis of sleep apnea is made when an AHI of five or greater is combined with daytime sleepiness. In general, the higher the AHI, the more severe the apnea.