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.
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