Are sleep apnea and cognitive impairment connected?

sleep apnea

When you are reviewing a patient’s chart, do you take note of respiratory dysfunction such as obstructive sleep apnea syndrome and chronic obstructive pulmonary disease? Hopefully you do in relation to dysphagia. But what about in relation to cognitive impairment? I believe it is within our scope of practice to understand why our patients are experiencing cognitive impairment. This puts us in a position to provide more holistic treatment and recommendations.

Obstructive sleep apnea syndrome (OSAS) is a diagnosis you should look for in charts and question whether those who have not been diagnosed with sleep apnea should be referred to a specialist. We should do this much in the same way we would refer to a neurologist when we question whether a person has a brain tumor causing cognitive impairment. It is not within our scope of practice to diagnose these conditions. However, we would provide our patients with great benefit if we consider why cognitive impairment is occurring. After all, with some conditions medical treatment can reverse the cognitive impairment or stop progression.

Neurocognitive impairment in obstructive sleep apnea

I frequently read the CHEST journal, which is a publication for chest medicine specialists (respirologists, critical care physicians, sleep specialists, cardiothoracic surgeons and allied healthcare professionals). I found this publication when looking for information about aspiration pneumonia. They have many articles available for FREE. In 2012 CHEST published Neurocognitive impairment in obstructive sleep apnea. We often think about hypoxia impacting cognitive function, but what about obstructive sleep apnea, whether it be untreated, undiagnosed, or noncompliant treatment?

While the prevalence of cognitive impairment in patients with obstructive sleep apnea is unknown, one observational study revealed 25% of patients with OSAS had some level of cognitive impairment. Other studies has showed OSAS results in abnormalities in two areas: psychomotor function and cognitive impairment. Studies indicate people with OSAS typically have the following pattern of cognitive impairment:

  • Attention or “vigilance” deficits
  • Memory impairment
  • Executive dysfunction
  • Global intelligence is a relative strength

OSAS has also been associated with mild cognitive impairment. Some studies have reported sleep disruptive breathing (SDB), a less severe form of obstructive sleep apnea, may also increase risk of cognitive impairment.

Brain imaging for cognitive impairment with sleep apnea

Several studies have conducted brain imaging for patients with sleep apnea. Neuroimaging included structural MRI, functional MRI, and magnetic resonance spectroscopy. In conducting neuroimaging studies researchers are trying to determine if and where sleep apnea negatively impacts the brain. Some studies reported no differences in white matter, periventicular hyperintensities, or gray matter in people with sleep apnea compared to normal subjects. However, there have been several studies that have found significant differences between the OSAS and normal subjects.

These studies have suggested OSAS correlates with decreased gray matter in the hippocampus, anterior cingulate, cerebellum, and the frontal, parietal, and temporal lobes. Other studies have revealed “decreased brain activation in the cingulate, frontal, and parietal regions during the performance of sustained attention tasks as compared with control subjects.” One study revealed gray matter loss can be reversed when the subject was compliant with sleep apnea treatment. (The current gold standard for treatment is a CPAP or continuous positive airway pressure.) After treatment significant gains were found in cognitive performance as well as a reversal in gray matter loss in the left hippocampus, left posterior parietal cortex, and right superior frontal gyrus. Could early detection and treatment of sleep apnea prevent long term cognitive impairment?

Consistent throughout the studies that found a difference between people with sleep apnea and normal controls was decreased hippocampal volume. Remember the hippocampus? It is very important for memory consolidation. A study looking at guinea pigs with sleep apnea revealed recurrent apnea resulted in excitotoxicity of hippocampal neurons, which results in apoptosis or cell death. We also think of the hippocampus being one of the first areas of the brain to be impacted by Alzheimer’s disease.

What do this mean for us?

More research in this area is needed. There are still many questions to research, but I see the information presented in this article as something to tuck away for later use. As I continue to be referred patients without a diagnosis that explains WHY they are experiencing cognitive impairment, I will consider sleep apnea as a cause and refer to specialists as appropriate.

The Sleep Foundation provides a list of the following symptoms for sleep apnea. “Chronic snoring is a strong indicator of sleep apnea and should be evaluated by a health professional. Since people with sleep apnea tend to be sleep deprived, they may suffer from sleeplessness and a wide range of other symptoms such as difficulty concentrating, depression, irritability, sexual dysfunction, learning and memory difficulties, and falling asleep while at work, on the phone, or driving.”

About a month ago I had a conversation with a gentleman on a plane about his father. His father had CHF and sleep apnea. He was noncompliant with his CPAP use; however, he used nocturnal supplemental oxygen. The son’s complaint was the father was forgetting more and falling asleep while driving. I urged him to have his father see a doctor to check his oxygen saturation during the day (also lived at high elevation) and discuss this problem in relation to the sleep apnea.

Do SLPs treat sleep apnea?

Most of the time, the answer to this question is no. However, Cyndee Bowen of Bowen Speech in Clearwater, Florida discovered a protocol for strengthening exercises to treat sleep apnea. When reviewing this protocol she found that it utilized knowledge that SLPs have and use in their treatment of dysphagia, motor speech, and voice. She has treated several patients using the protocol and found great results. Improvements include weight loss, reduced snoring, lower blood pressure, and lower cholesterol. Sleep studies have supported patient report of better sleep.

While a CPAP machine is considered the gold standard for treatment, compliance is a concern. (And the article I reviewed today gives us good cause to urge compliance with sleep apnea treatment.) This protocol shows some promise for people that cannot or choose not to utilize a CPAP machine in their treatment of sleep apnea. You can read more about the treatment in a case study on her blog.

Rachel Wynn
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Rachel Wynn

Speech-Language Pathologist at Gray Matter Therapy
Rachel is a speech-language pathologist and creator of Gray Matter Therapy. She started making noise as a patient-centered care advocate in 2013. She believes great care happens when patients are informed and engaged.
Rachel Wynn
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  • Geoff Ellerton

    I had severe sleep APNEA. I’m 58yo. In February, I had a test: stopped breathing 33 times/hour. 94% oxygen level to the brain. My doctor told me to lose my gut (hence the fat around my neck). I have lost 32kg (from 110 to 78kg) over 5 months. My wife says that I’ve stopped snoring and when I wake up, I feel as though I had a sleep. Not refreshed, but not wasted. Previously I’d wake up and felt as though I’d been asleep for one minute – just exhausted all the time. Yawning at work. Falling asleep at home watching a good movie. Micro sleeps behind the wheel. Unable to get excited about anything, even watching my boys play sport. Flat emotionally. Difficulty organising things, making and sticking to plans. Making poor decisions. Worst of all I had very poor concentration, especially at work, trying to read, edit and write reports – I’d last 5 minutes and find myself doing a different task. It had a huge impact on my work performance. It has been 2 months since I lost the weight. Slowly my ability to concentrate and stick to the reports is increasing. Is this normal? How long does it take to be running at top gear again? My boss doesn’t say it, but he thinks that I’m not interested and just bludging, and gave me a poor performance review.

    • Rachel Wynn

      I am so glad that lifestyle changes have improved your sleep apnea. Since there are many things that contribute to cognitive dysfunction, this is a great question to ask your doctor. Your doctor will be able to give you a more accurate response based on your body. All of the body’s systems are connected. Your doctor will also be able to test for other things that may result in poor concentration, sleepiness, and feeling emotionally flat, such as thyroid dysfunction and vitamin and mineral deficiencies.

  • Kim Shannon

    I have recently been diagnosed with mild OSA. After reading the comment left by Geoff I also suffer with the same symptoms. I thought I was getting Dementia, which really alarmed me. My cognitive abilities are impaired. I suffered in silence because I didn’t want anyone to know how I was feeling. At work was extremely taxing, I would have to make lists to remind me what I had to do during the day. I felt tired, yawned, couldn’t concentrate and took me longer to complete tasks. By the end of the day I am exhausted. During my sleep test my blood oxygen levels dropped to 84% and wake up feeling I haven’t slept. My work is quite demanding. I am an office administrator and need to be focused. I was doing a Degree at Uni and had to pull out because of these symptoms. I just hope the breathing machine will help with these symptoms. I also suffer with a lung disease, which doesn’t help.

  • Gaylene

    I LOVE this article. My daughter shared it with me. She is at Penn State finishing her Master’s in SLP. I also experienced negative thoughts for years that subsided after I had been on my CPAP and O2 at the right settings for a significant period oftime! I read, (somewhere?) That others have experienced the same! I am trying to be an advocate and educating as I can about the affects of sleep apnea! Thank you for your work!

  • How About No

    As a sleep apnea patient with 100 (!) AHI at the time of my diagnosis, I strongly agree with the argument that OSA, especially very severe cases, can markedly impair executive function, reaction time, and the ability to stay focus on tasks and details.

    With CPAP, I have tons of energy, I don’t stutter, I can explain my self clearly, I can hold conversations, I can think on my feet, and I can work proficiently in my second language.

    Without it, I can barely stay awake and have to rely on global intelligence and memory to tread water.

    It may have taken nearly 32 years, but with treatment, I am much stronger cognitively at 34 than I was at 18!