Sleep Apnea May Increase Risk of Dementia and Memory Loss

Couple sleeping in bed in the morning
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Got a loud snorer with sleep apnea next to you in bed? If so, he or she may be at risk for more than just your irritation from waking you up again. Several research studies have concluded that those with sleep apnea may have an increased risk of memory problems, such as mild cognitive impairmentAlzheimer's disease, and unspecified dementia. Don't despair, however. There may also be a fairly easy way to minimize the risk.

About Sleep Apnea

Sleep apnea is a condition where you stop breathing when you sleep. According to Verywell's sleep disorders expert, Dr. Brandon Peters, you might hold your breath for 10 seconds, begin breathing again, and then repeat this more than 100 times a night. You might snore, gasp for breath, or cough frequently as your body works to compensate for sleep apnea. As you can imagine, this disturbs your sleep repeatedly.

Approximately one in four adults between the ages of 30 and 70 has sleep apnea. Sleep apnea has already been connected to high blood pressure, heart disease, stroke, type 2 diabetes, and depression.

Review the symptoms of obstructive sleep apnea and consult your physician if you're concerned you may be experiencing sleep apnea.

Sleep Apnea and Dementia Risk

Several researchers have studied sleep apnea to learn if, and how, it may be connected to brain functioning, memory, and risk of dementia.

In one scientific review, researchers looked at several of the prior studies that had been conducted on sleep apnea and dementia and found a strong connection between the two factors. Specifically, people who had Alzheimer's disease were five times more likely than those without Alzheimer's to also have sleep apnea.

Additionally, they found that approximately half of the studies' participants who had been diagnosed with dementia had experienced sleep apnea at some time after their diagnosis.

A different study published in the journal Neurology and conducted at the New York University School of Medicine outlines research conducted with more than 2000 participants. After reviewing the sleeping patterns and cognitive functioning of these participants, the researchers reached the following conclusions:

  • Persons with sleep apnea developed mild cognitive impairment about 10 years earlier in life than those without sleep apnea. (Mild cognitive impairment increases your risk of dementia, but some people with MCI remain quite stable in their functioning.)  
  • Sleep apnea was correlated with the presence of Alzheimer's at a younger age—age 83 compared to age 88 in those without sleep apnea.
  • Here's the good news: In the study, people who were treating their sleep apnea by using CPAP machines gained about 10 years of cognitive functioning. They developed mild cognitive impairment (MCI) at about age 82, while those who did not treat their sleep apnea developed MCI at approximately age 72.

A third study found that sleep apnea was correlated with a decrease in hippocampal volume and increases in white matter lesions in the brain—changes that often occur with cognitive problems such as Alzheimer's disease.

Another study determined that people with sleep apnea who had seemingly normal cognitive functioning actually demonstrated decreased delayed recall and a decline in executive functioning when tested with the Trail Making Test. (The Trail Making Test is one of many cognitive screening tests.) Executive functioning deals with the ability to organize and plan multiple tasks, as well as monitor our own behavior.

Researchers in a fifth study that reviewed over 400 female participants found that women with sleep apnea had a higher likelihood of cognitive problems, including dementia.

One other study identified deficits in attention, executive functioning, visual-spatial ability and delayed memory in participants with sleep apnea, but also found that CPAP treatment improved those symptoms.

What Are CPAP Machines?

CPAP machines treat sleep apnea by using a mask to place pressurized air in your mouth to keep your airway open. Multiple studies found that CPAP treatment may be able to help address the decline in thinking and memory connected with sleep apnea. Many people report an improvement in their sleeping and functioning after using a CPAP machine. 

Next Steps

While these studies don't prove that sleep apnea causes dementia, they do show a fairly strong correlation. In light of this, as well as the other health risks that sleep apnea has been tied to, identification and treatment by a physician is strongly recommended. Addressing your sleep apnea could be a fairly simple way to improve your current and future health, both for your body and your brain.

Sources:

Ducca EL, Gumb T, Pirraglia E, et al. Sleep-disordered breathing advances cognitive decline in the elderly. Neurology. April 2015:10–1566. 

Emamian F, Khazaie H, Tahmasian M, et al. The association between obstructive sleep Apnea and Alzheimer’s disease: A Meta-Analysis perspective. 2016;8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4828426/. 

Ju G, Yoon I, Lee S, Kim T, Choe J, Kim K. Effects of sleep apnea syndrome on delayed memory and executive function in elderly adults. Journal of the American Geriatrics Society. 2012;60(6):1099–103. https://www.ncbi.nlm.nih.gov/pubmed/22646710.

Kinugawa K, Nguyen-Michel V, Mariani J. [Obstructive sleep apnea syndrome: A cause of cognitive disorders in the elderly?]. La Revue de medecine interne. 2014;35(10):664–9. https://www.ncbi.nlm.nih.gov/pubmed/24630586.

Rising prevalence of sleep apnea in U.S. Threatens public health - American academy of sleep medicine (AASM). http://www.aasmnet.org/articles.aspx?id=5043

Yaffe K, Laffan AM, Harrison SL, et al. Sleep-disordered breathing, Hypoxia, and risk of mild cognitive impairment and dementia in older women. JAMA. http://jamanetwork.com/journals/jama/fullarticle/1104205​

Zhonghua Yi Xue Za Zhi. 2014 Dec 2;94(44):3483-7. [Association between inflammation and cognitive function and effects of continuous positive airway pressure treatment in obstructive sleep apnea hypopnea syndrome].

Zhonghua Yi Xue Za Zhi. 2014 Mar 18;94(10):724-8. [Correlation between cognitive function and hippocampal atrophy and cerebral white matter lesions in patients with obstructive sleep apnea hypopnea syndrome].

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