Sleep-disordered breathing.
Sleep-disordered breathing (SDB) is a broad term used to describe the presence of abnormal respiratory events that occur during sleep. Sleep apnea, one of the SDB disorders, is a common condition that causes you to stop breathing for short intervals while you sleep. When left untreated, it can have significant health effects over the long term. The clinical diagnosis of sleep apnea syndrome is made when apneas (complete cessations of breathing) and hypopneas (partial cessations of breathing) are present in conjunction with excessive daytime somnolence. The etiology of apneas and hypopneas is frequently anatomical and involves a narrowing or collapse of the pharyngeal upper airway when an individual is lying in a supine position during sleep. Apneas and hypopneas may occur occasionally or up to several hundred times a night and are associated with intermittent hypoxemia (e.g. significant drops in blood oxygenation). In addition, each breathing event causes involuntary and usually unconscious arousals in order to resume respiration, ultimately leading to sleep fragmentation. Sleep disorders – they’re common in older adults. There is ample evidence to date that SDB and age have been shown to be independent risk factors for cognitive dysfunction and dementia. The prevalence rates of OSA (obstructive sleep apnea) and SDB has been reported to be up to 62% among the elderly. What is the reason for a disproportionately higher rate? Competing mechanistic causes include age-related changes in pharyngeal and upper airway muscle size and function, increased sleep fragmentation, instability in ventilator control, and differential effects of hormones on upper airway function.1 SDB and the Brain. Our brains require a tremendous amount of energy and in order to meet this demand the flow of blood must be precisely choreographed to ensure that oxygen is adequately delivered where and when it is needed. A recently published study, “Association of Sleep-Disordered Breathing with Alzheimer’s Disease Biomarkers in Community-Dwelling Older Adults”2 examined the relationship and identified several important results, The SDB-associated brain changes in older adults who are cognitively unimpaired include greater amyloid deposition and neuronal activity in Alzheimer’s disease-sensitive brain regions, notably the posterior cingulate cortex and precuneus, which is involved in a variety of complex functions including memory, recollection, cue reactivity and perception. These results support the need to screen and treat for SDB, especially in asymptomatic older populations, to reduce the risk of Alzheimer’s disease. As a respiratory disorder, we know that SDB is characterized by recurrent upper airway collapse during sleep, associated with intermittent hypoxia and sleep fragmentation that affects 30 to 80% of older adults who are cognitively unimpaired, depending on the SDB definition criteria. Let’s look at the mechanisms in how SDB affects the brain: ▪ Increase in amyloid. ▪ Reduction or increase in gray matter in frontal, temporal and parietal. ▪ Decreased vascular supply whereby chronic intermittent hypoxemia causes a vasculopathy that ultimately is expressed as cognitive impairment and functional decline in the older adult. ▪ Genetics: Those with the APOE4 allele (widely considered the vulnerability factor) may be more at risk to the effects of SDB. In this particular study, researchers noted: 1. Participants with SDB presented greater amyloid burden in the left precuneus, posterior cingulate, calcarine, and cuneus regions and that the greater amyloid burden was robustly associated with the severity of hypoxia. This is consistent with animal studies, showing that hypoxia promotes the cleavage of the amyloid precursor protein by the β-secretase and γ-secretase, leading to increased β-amyloid levels. 2. Greater gray matter (GM) volume, metabolism, and perfusion in parietooccipital regions, including the precuneus and posterior cingulate cortex. The authors note too that in other studies, decreased cortical volume (or gray matter) has been found, but state that this may be attributable to methodological differences and the severity of the SDM (e.g. because most studies have been performed on smaller samples of young and middle-aged participants with severe SDB (AHI >30 events per hour) Note too, the apnea-hypopnea index (AHI) value is the sum of apnea and hypopnea events per hour of sleep. In this study, the level of SDM was mixed with moderate (AHI greater than 15 events/hour) and severe. The greater GM volume is probably due to high neuronal activity, metabolism and perfusion as the brain is trying desperately to maintain oxygenation during the hypoxia occurring in sleep. 3. High neuronal activity goes hand in hand with increased production of amyloid. 4. In this study, these changes noted on imaging were not associated with self-reported cognitive decline or problems. So what does all this mean and what are the implications? This study exemplifies once again the tremendous risk related to sleep-disordered breathing. Older adults with SDB may exhibit silent brain changes, including increased amyloid deposition, which may propagate with time and explain why they are more at risk of developing Alzheimer’s clinical syndrome – which leads us to believe that every patient exhibiting cognitive impairment should have a thorough evaluation of their sleep. How is sleep apnea or other sleep disorders diagnosed? Healthy people typically have oxygen saturation between 96-99%. During the night, your goal is to maintain oxygen levels around 95-98%, ideally as close to your daytime levels as possible. If you live at a higher altitude, this will drop accordingly. Obstructive sleep apnea (OSA) is diagnosed with repeated episodes of desaturation, where blood oxygen levels drop to <90%. In severe cases this can happen repeatedly throughout the night (greater than 30 per hour) with oxygen saturation <80%. Central sleep apnea (CSA) is not from a mechanical obstruction of the airway, but occurs when the brain doesn't send proper signals to the muscles that control breathing. Mixed sleep apnea (MSA) is a combination of CSA and OSA. Upper airway resistance syndrome (UARS) is another possible cause of airway obstruction although notably these patients are typically not overweight. If your doctor suspects sleep apnea, they may recommend a sleep monitoring test. Also called a sleep study or polysomnography (PSG), it involves spending the night at a lab, clinic, or hospital. Your breathing and other vital signs will be monitored while you sleep. An at-home sleep test is a simplified version of an in-lab test and requires no technician. Instead, your doctor will prescribe a portable breathing monitor kit that you’ll take home along with instructions for self-administering the test. Doctors use a scale called the Apnea Hypopnea Index (AHI) to diagnose sleep apnea. This scale includes a measurement of the number of apneas, or lapses in breath, per hour of sleep during the study. People who don’t have sleep apnea, or have a mild form of sleep apnea, usually experience less than five apneas per hour. In contrast, people with a severe form of sleep apnea may experience more than 30 sleep apnea episodes per hour. What Dr. Dale Bredesen Recommends. Dr. Bredesen is a renowned physician whose work in the field of Alzheimer’s has been widely employed in integrative medicine practices; note that I am also certified in the Bredesen Protocol®, about which you can learn more in our Medical Resources section. You can ask your own physician for a prescription to rent a continuous pulse oximeter or you can purchase a system to monitor your oxygen saturation at home. There are two products we like because of their medical grade accuracy. The first is the Innovo 50f Plus ($149.99), which is a snug fitting wristwatch that provides continuous monitoring of oxygen saturation and pulse rate with 24-hour data collection and analysis. You can use either bluetooth or a cable to download the collected data to your personal computer (PC) via Windows. You can also easily use this device during the day to monitor your oxygen levels. The only downsides are that it isn't compatible with Apple or Android devices and some people find it difficult to sleep with a tight-fitting watch. Another option is the BEDDR Sleep Tuner ($149), which is both Apple and Android compatible. BEDDR uses a small optical sensor that adheres to the middle of your forehead to measure blood oxygen levels and heart rate throughout the night. BEDDR provides a detailed report that you can see on your smartphone or tablet. The only downside to this device is that it's only practical for nighttime use. For an inexpensive option consider an inexpensive, small, portable and clip-on pulse oximeter called Innovo Deluxe ($27) which will easily allow you to monitor your oxygen saturation by clipping the device on the end of your finger, not unlike a clothespin, but much gentler. Another home monitoring device is the Sleep Stat and is a 3-D Hi-Resolution Technology Pulse Oximeter with advanced pattern detection. We have this available in our offices and it can be assigned for patients’ use at home ($150). A “CPT code” will be provided so that you can submit this as a claim to your insurance company. (We’ve included links to each of these products at the end of this article for further reference.) Lifestyle treatment options. There are some additional things you can do at home to potentially improve your sleep and sleep apnea: ▪ Losing weight may also help reduce airway obstruction. ▪ Try using a special sleep apnea pillow. Your doctor may have specific recommendations or ask one of our clinic team members for more information. ▪ Change your sleep position. Sleeping on your side or stomach may help keep your tongue from adding to airway obstruction. Otherwise if you tend to sleep on your back, ideally keep your head elevated. ▪ Practice breathing deeply with the goal being to switch to deep even breaths through your abdomen, called diaphragmatic breathing. Follow these steps to optimize your cardiovascular fitness – better blood flow to the body means better blood flow to the brain! 1. Inhale slowly and deeply through your nose, keeping shoulders relaxed. Try to make your abdomen expand with each breath while your chest only rises very little. It is very important to breathe through your nose 2. Exhale slowly through your mouth, keeping your jaw relaxed. You may hear a soft whooshing sound as you exhale. 3. Repeat this exercise for several minutes. Observe how relaxed you feel afterwards. Medical treatment options. There are a number of effective medical treatment options for sleep apnea, depending on the degree of severity that include: ▪ Continuous positive airway pressure (CPAP). The most common and effective device for treating sleep apnea is a machine called a CPAP. With this device, a small mask is used to increase the pressure in your airways. ▪ Oral appliances. A dental device that pushes your lower jaw forward can prevent your throat from closing while you breathe. These may be effective in mild to moderate cases of sleep apnea. ▪ Nasal device. Provent Sleep Apnea Therapy has been shown to be effective for some cases of mild to moderate sleep apnea. This small, bandage-like device is placed just inside the nostrils and creates pressure that helps keep your airways open. ▪ Oxygen delivery. In some cases, oxygen may be prescribed in combination with a CPAP device to increase blood oxygen levels. ▪ Surgery. When other treatments aren’t effective, surgery might be an option to alter the structure of your airways. Your physician can explain more about the wide range of surgical options to treat sleep apnea. We’ve often spoken about the value of restful sleep as part of a healthy lifestyle approach – and you can see just how important it is for your brain’s wellbeing too! So be sure to stay on top of any treatment for your sleep apnea or address chronic sleep issues with your doctor. As always, we’re here to help so let us know if you have questions or need to schedule an appointment. In health and hope, Dr. Suzanne Gazda 1 Zimmerman, M. E., & Aloia, M. S. (2012). Sleep-disordered breathing and cognition in older adults. Current neurology and neuroscience reports, 12(5), 537–546. https://doi.org/10.1007/s11910-012-0298-z 2 André C, Rehel S, Kuhn E, et al. Association of Sleep-Disordered Breathing With Alzheimer Disease Biomarkers in Community-Dwelling Older Adults: A Secondary Analysis of a Randomized Clinical Trial. JAMA Neurol. 2020;77(6):716–724. doi:10.1001/jamaneurol.2020.0311 For more information about devices or products mentioned in this article: Innovo https://innovo-medical.com/ BEDDR Sleep https://www.beddrsleep.com/ Sleep Stat https://www.marketing.patientsafetyinc.com Provent https://www.proventtherapy.com/ Which Type of Sleep Apnea Test Is Right for You? https://www.healthline.com/health/sleep-apnea-test#at-home-sleep-tes
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AuthorDr. Suzanne Gazda, Integrative Neurology Archives
February 2024
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