Features September 2012 Issue

Take Charge of Manageable Stroke Risk Factors, Such as Poor Sleep

New studies show an association between stroke and risk factors such as low vitamin D levels and insufficient sleep.

Among the many risk factors for stroke, some, such as age and family history, are well beyond our control. Others, such as atrial fibrillation and hypertension, can pose a great challenge to keep under control. But some risk factors, such as weight, smoking, exercise and sleep apnea are manageable with some effort and the understanding that improvements you make in these areas can directly lower your odds of having a stroke.

Two recent studies also identify two possible risk factors that may be within your power to manage and further protect yourself against stroke.

The first is an observational study, published online May 24 in the journal Stroke, and it found that low vitamin D levels are associated with a higher risk of stroke. But there remains some question whether it’s actually the levels of vitamin D in the body that affect stroke risk. “There is accumulating evidence correlating vitamin D levels to other markers of risk or other risk factors of cardiovascular events,” says Cleveland Clinic cerebrovascular specialist Ken Uchino, MD. “However, as with many investigations of risk factors, there are still questions.”

More about Vitamin D
Vitamin D has been the subject of numerous studies recently examining the nutrient’s role in heart and brain health. It is still unclear, however, just what low vitamin D levels mean for long-term cardiovascular and cerebrovascular health. One study from earlier this year notes that too much vitamin D can be just as unhealthy for the brain as too little.

As for the study published in Stroke, Dr. Uchino suggests that low vitamin D levels might be a marker of stroke risk, rather than a mediator of risk.

“For example, vitamin D is affected by kidney disease, which affects blood pressure,” he explains. “It’s notable that in this study, the vitamin D association was strongest with so-called lacunar infarction, which is thought to arise primarily with changes in blood vessels due to high blood pressure.” Lacunar infarction is a type of stroke that affects the arteries deep in the brain.

Dr. Uchino also suggests that vitamin D levels may simply reflect the lifestyle of the individual, and that a person who consumes a healthy diet rich in vitamin D sources, such as salmon, tuna, and foods fortified with vitamin D, might also engage in other healthy behaviors.

Sleep and Stroke
A healthy lifestyle with attention to stroke prevention should also include getting sufficient sleep. In a study presented at the SLEEP 2012 conference in June, researchers found that habitually sleeping less than six hours a night significantly increases the risk of stroke in middle-aged and older adults who are of normal weight and low risk for obstructive sleep apnea (OSA).

Adults with OSA are automatically at a higher risk for stroke.

Dr. Uchino says that, like the vitamin D study, this sleep study cannot answer exactly why short sleep raises the risk of stroke. Exploring the causes of insufficient sleep may lead to more helpful answers. “It is again possible that sleep reflects other unmeasured problems, and that trying to sleep longer than six hours may not reduce the risk of stroke,” he says. “Depression is a common cause for sleep disturbance and poor health behavior.”

The Bottom Line
Dr. Uchino recommends a frank discussion with your physician about how you can better manage your controllable risk factors. And if you are experiencing problems such as side effects from your blood pressure medication, talk with your doctor about alternative drugs, different doses or changing the timing of your dose, rather than just stopping the medication altogether.

“Taking care of heart issues pretty much takes care of stroke risk factors, too,” Dr. Uchino says. “These include cholesterol, blood sugar, smoking, physical activity, sleep apnea, etc. Atrial fibrillation, though, stands out as something different than the above risk factors. Atrial fibrillation is an important cause of stroke, but does not cause heart attack. Also, blood pressure has a much greater influence on stroke than heart attack.”