Does Sleep Apnea Cause Dementia?
Does lack of rest fundamentally damage the brain?
Posted Aug 17, 2011
Fear of Losing One's Mind
Lots of us are scared of dementia -- really scared. You spend your life doing "all the right things" -- you floss twice a day, run five miles daily till your knees give out, eat kale and force yourself to meditate, and you still see a future where your kids visit and hide their faces when you can't remember their names. Most people will do most anything to avoid that fate.
Now there's something else to be frightened of -- sleep apnea -- stopping breathing during sleep. A recent study took a community survey study of osteoporotic fractures and grafted on a study of sleep disordered breathing. They found that certain elements associated with sleep apnea -- which generally affects the majority of people over 65 -- increased the risk of dementia over five years. But before you reach for the air splinting CPAP device that was recently declared the gold standard for sleep apnea, take a breath. You need to see what this study by Yaffe, Redline, Ancoli-Israel and other leaders in the field really says -- and then use to learn what you can do to prevent dementia in your own life.
These Folks Were Old
The study was performed on 298 mostly white women of average age 82, followed up five years after an at-home sleep study. Think about it -- that's older than the average survival age of American women. It's been known for a long time that sleep apnea in younger ages can increase mortality, but more recent studies argue that you need sleep apnea plus daytime sleepiness to increase mortality in the elderly. It seems there's a survival effect -- the older you are, the less the impact of apneas on shutting off your life. And there was some evidence for just this in this study's results.
They Didn't Get Enough Oxygen
In looking at the group who got dementia, you needed more than 15 apneas or hypopneas per hour and hypoxia -- markedly lower oxygen levels during the apneas -- or 15 or more apneas plus hypoxia for more than 7 percent of the time you were asleep.
The researchers controlled for variables like diabetes, hypertension and depression that predispose to dementia. If you had lots of apneas without hypoxia -- no increase in dementia. If you slept poorly with many interruptions, which normally interferes with memory -- no increase in dementia. If you slept ineffectively, waking up and staying up -- no increase in dementia. It seems that if you can get into your 80s in relatively good health, you may be pretty good at adjusting to poor sleep -- as long as you don't get hypoxic.
Why Was Low Oxygen So Important?
Low oxygen is bad for you -- if the level gets too low, you die. But intermittent hypoxia kills brain cells -- and other kinds of cells too. Lots of apneas and hypopneas is a terrific way to set up intermittent hypoxia.
So What Can I Do To Avoid Dementia?
Plenty. Alzheimer's is the most common form of dementia, and the Alzheimer's Association International Conference just came out with estimates of the proportion of Alzheimer's disease cases attributable to the following risk factors:
In the U.S.:
Take a look at that list. Even given present limited knowledge of what causes Alzheimer's, the majority of risk is controllable -- and vascular dementia, also common, may be more controllable still.
Now let's add in hypoxic sleep apnea as a risk factor for dementia. Many of the risk factors turn out to be the same -- weight gain, physical inactivity, hypertension, diabetes. So combating sleep apnea will also combat dementia.
What You Can Do
Much of these risk factors involve three basic things in life: food, activity and rest. So let's go through the list:
Physical inactivity: you don't have to move much to get a big bang for your buck. Even 10 or 20 minutes of ambling and strolling will make a difference, with Ralph Paffenbarger and many others showing lifetime increase with just 60 minutes of physical activity a day, total.
Depression: Bedeviling more and more Americans, there is considerable evidence that walking -- especially in the morning, with morning sun light -- can work well at treating depression.
Smoking: Many more treatments, like chantix and cognitive behavioral techniques, are available than in the past. And since many smoke for a reason, replacing smoking with other behaviors -- like walking -- is an excellent way to cut stress and decrease the need for tobacco.
Mid-life hypertension, obesity and diabetes -- lack of sleep can worsen all of them -- and walking and eating whole foods -- like plants -- can decrease their risk.
There are other ways to lower your dementia risk. Life space is a measure of how much people get out. A recent study from Rush Medical School in Chicago showed great decreases in Alzheimer's risk for elderly who just got out of the house -- traveling from where they lived. Controlling for heart disease and even social support did not change that result.
So there's lots you can do to prevent Alzheimer's disease, other dementias, sleep apnea and many of the scourges of aging. The simplest may be the most effective -- just get out and walk. And if you can, do it with a friend, gaining social support -- in the morning, when you reset clocks and have the mood enhancement of early light.
And even if your risk of apnea is low, morning walks should improve your sleep at night. Simple things can really work.
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