As we age, it is normal to experience some cognitive decline. Our memories become less sharp, and new information is not so easily assimilated and put to use. This normal decline is not the same thing as dementia, a condition that affects an estimated five million people in the U.S. While we can take good steps to stay mentally active, there are some surprising causes of dementia. Sleep apnea and dementia are actually linked in an increasing number of studies. Here’s what you need to know.
Does sleep apnea cause brain damage?
For the estimated 25 million people in the U.S. who suffer from sleep apnea, a poor night’s sleep accompanied by lack of focus and mental fogginess the next day is a regular occurrence. Sleep apnea takes three forms:
- Obstructive sleep apnea: The tissues of the throat relax during sleep, blocking the airway
- Central sleep apnea: This is a malfunction of the central nervous system whereby it essentially forgets to tell the sleeper to breathe during the night
- Complex sleep apnea: Complex sleep apnea is a rare and dangerous combination of the other two types of sleep apnea
All three forms of sleep apnea not only cause daily challenges, but come with significant long-term health risks that include stroke and cardiovascular disease.
The long-term effects of sleep apnea may also lead to permanent changes to the brain. Over time, sleep apnea seems to change both the brain’s structure and function, causing brain damage. Emerging studies indicate that this occurs in two specific ways.
1. Obstructive sleep apnea promotes the build-up of beta-amyloid
Beta-amyloid is a key marker of Alzheimer’s disease. Researchers already know that the more of this protein there is, the faster the cognitive decline.
A study in 2017 found more beta-amyloid in the brain in patients with obstructive sleep apnea. The glymphatic system, responsible for cleaning away beta-amyloid during sleep to prevent its build-up, just does not have enough quality sleep time or oxygen to function correctly in a patient with sleep apnea.
2. Lack of oxygen thins the brain’s temporal lobes
Another study in 2018 found that patients with sleep apnea experienced a thinning of the right and left temporal lobes, areas that are significantly changed by Alzheimer’s disease. This reduces the brain’s ability to learn and retain new information. There was also an increased thickness in other areas of the brain, potentially caused by inflammation prompted by low oxygen levels.
These changes to the brain appear to be permanent and irreversible.
What are the long term effects of untreated sleep apnea?
The long-term health risks of undiagnosed and untreated sleep apnea are well-documented and include:
Less well-known but receiving increased research focus is the connection between sleep apnea and dementia, including Alzheimer’s.
Sleep apnea and dementia
Dementia is a condition of cognitive impairment and loss of cognitive function that does not necessarily come with physical changes to the brain. There are a variety of brain patterns and changes that can come with dementia, including potential vascular impairment. Nevertheless, sleep apnea can affect daily cognitive function and progress over time.
In some cases, sleep apnea symptoms also mimic dementia symptoms: trouble with memory, focus, and concentration. Many doctors are now recommending polysomnography – sleep testing – for elderly patients who are concerned about dementia or cognitive decline. The sleep apnea diagnosis can be missed, especially among those patients who live alone.
Dementia differs from other types of cognitive impairment in that some cases can be treated and successfully reversed.
Sleep apnea and Alzheimer’s
Sleep apnea and Alzheimer’s disease have a strong connection, with sleep apnea ultimately both increasing the risk of Alzheimer’s and speeding up its progression.
Alzheimer’s disease is the most common form of dementia. This disease is significantly impacted by the presence of sleep apnea. The oxygen deprivation of sleep apnea indicates a risk of Alzheimer’s that is three times higher in sleep apnea patients than those who experience regular sleep.
Sleep apnea has also been related to an earlier onset of mild cognitive decline. A study in 2015 looked at patients between the ages of 55 and 90 and found that those with sleep disordered breathing had an average onset of a decade earlier than tho