Sleep apnea is a common but often undiagnosed sleep disorder characterized by repeated interruptions in breathing during sleep. These interruptions, known as apneas, last from seconds to minutes and can occur several times an hour. Obstructive sleep apnea (OSA), the most common type, occurs when the muscles in the neck relax too much, blocking the airway.
Symptoms include loud snoring, excessive daytime sleepiness, and restless sleep, which can greatly affect quality of life. Approximately 6 million Americans have been diagnosed with sleep apnea, but it is estimated that up to 80% of adults with OSA remain undiagnosed.1 This means that nearly 30 million Americans suffer from sleep apnea, and most of them don’t realize it.2
This high prevalence highlights the importance of awareness and screening. Especially because OSA is not only devastating but is also linked to a number of serious health conditions. Although men are generally more likely to be diagnosed with OSA than women, research suggests that women may suffer more severe consequences from this disorder, especially when it comes to cognitive health.3
The link between sleep apnea and dementia
Results of a comprehensive, 10-year longitudinal study published in SLEEP Advances highlight the association between known or suspected OSA and the risk of developing dementia, particularly in older women.
The study analyzed data from the Health and Retirement Study (HRS), which included 18,815 participants aged 50 and older who did not have dementia at the start of the study. By following these individuals over 10 years, researchers aimed to uncover how OSA affects the likelihood of developing dementia.
The results are revealing. Both women and men with known or suspected OSA had a higher cumulative incidence of dementia compared with women without OSA. Specifically, by age 80, women with OSA had a 4.7% higher risk of developing dementia, while men had a 2.5% higher risk.4 The association remained significant after adjusting for factors such as race, education, and marital status, highlighting that OSA is an independent risk factor for dementia.
Why older women are especially at risk
The study found that women with OSA were at a disproportionately higher risk of developing dementia. Several factors contribute to gender-specific vulnerability. Women with untreated OSA often experience more severe symptoms, including poor sleep quality, increased fatigue, anxiety, and depression.5 These downstream effects have a more pronounced impact on cognitive function over time.
Women are also more likely to suffer from cardiovascular complications associated with OSA, including high blood pressure and heart disease, which are risk factors for dementia. The intersection of OSA and other health conditions worsens cognitive decline in women, making them more vulnerable to dementia compared to men.
A significant challenge in addressing OSA-related dementia risk is the high rate of undiagnosed cases. This study used a modified version of the STOP-Bang questionnaire, a validated screening tool, to identify both diagnosed and suspected cases of OSA.
By capturing these undiagnosed cases, the study provides more accurate estimates of the true prevalence of OSA and its impact on cognitive health. This is important because undiagnosed OSA remains untreated, resulting in persistent disability and accelerated cognitive decline. Therefore, early identification and treatment of OSA may play a pivotal role in reducing dementia risk, especially in older women who are already at higher risk.
The relationship between OSA and dementia is complex, involving multiple biological and physiological mechanisms. Chronic disruption of breathing during sleep causes intermittent hypoxia (low oxygen levels) and fragmented sleep, both of which cause significant stress on the brain.
This stress can contribute to the buildup of amyloid beta and tau proteins, which are hallmarks of Alzheimer’s disease, the most common form of dementia. Additionally, OSA is associated with systemic inflammation that impairs cognitive function and promotes neurodegeneration.
Sleep Consolidation — A Key Element of Cognitive Function
In addition to the well-known risks associated with OSA, research highlights the role of sleep enrichment in maintaining cognitive health as we age. Sleep consolidation refers to uninterrupted, continuous sleep that allows the brain to cycle effectively through the various stages of sleep, including the deep recovery stages.
A study of 5,946 middle-aged to older adults published in JAMA Network Open found that better sleep maintenance efficiency (essentially fewer awakenings during the night) and reduced wake time after sleep onset were associated with superior overall cognitive function. It was revealed that they were related.6
Imagine your sleep as a symphony where each instrument represents a different stage of sleep. When sleep is integrated, these “instruments” play harmoniously without disruptive pauses.
This smooth progression through the sleep stages involves processes such as memory consolidation, where the brain organizes and stores information collected throughout the day. When this flow is disrupted, our ability to recall memories, solve problems, and maintain attention—key components of our cognitive health—is impaired.
Simply put, improving sleep continuity is critical to preserving cognitive function, and addressing sleep apnea, which leads to fragmented sleep, is part of that equation. According to the study, “poor sleep consolidation and prevalent OSA were associated with poorer overall cognitive performance within 5 years.”7 Adds support for the importance of addressing OSA to prevent cognitive decline.
Understanding the Biological Mechanisms Linking OSA and Dementia
The relationship between OSA and dementia reveals a complex web of biological mechanisms that underpin this association. One of the key mechanisms involves the intermittent hypoxia that is a hallmark of OSA. During apnea, oxygen levels drop, followed by periods of hypoxia and reoxygenation. This cyclical pattern creates oxidative stress and inflammation within the brain.8
Another pathway is the glymphatic system, which is responsible for removing metabolic waste from the brain. Fluctuations in intrathoracic pressure due to OSA disrupt the normal flow of cerebrospinal fluid, impairing lymphatic clearance of amyloid beta.
Sleep fragmentation also plays a role. Sustained sleep is essential for processes such as memory consolidation and synaptic remodeling. When sleep is fragmented, these processes are impaired, leading to deficits in memory, attention, and executive function.9 Over time, these chronic disorders contribute to the progressive decline in cognitive abilities observed in dementia.
Moreover, the chronic intermittent hypoxia and increased sympathetic activity associated with OSA lead to cardiovascular problems, creating a vicious cycle that puts both heart health and cognitive function at risk.
Neuroimaging studies have provided substantial evidence on the effects of OSA on brain structures. Patients with OSA often present with white matter lesions and gray matter atrophy in areas important for cognitive processing. These structural changes are associated with impairments in memory, executive function, and processing speed and link OSA to cognitive decline and dementia.10
Mouthguards, OMT and CPAP for the treatment of sleep apnea
Continuous positive airway pressure (CPAP) is considered the “gold standard” for the treatment of OSA.11 This treatment involves a small device that delivers a steady stream of air through a mask worn over the mouth, nose, or both. Continuous air pressure prevents airways from collapsing during sleep, maintains oxygen levels and improves sleep quality.
However, CPAP therapy also has its drawbacks. Some individuals may feel claustrophobic when wearing a mask, and common side effects include stuffy nose, dry mouth and eyes, and facial irritation from the pressure points of the mask. As an alternative, a mandibular advancement device (MAD), a type of mouthguard, provides an effective treatment with fewer side effects than CPAP.
MADs are custom-made by dentists in collaboration with sleep specialists. The device consists of two parts that fit over the upper and lower teeth and are connected by a mechanism that gradually moves the lower jaw forward. This repositioning moves the base of the tongue away from the airway, reducing the chance of a blockage.
The dentist will perform a thorough examination and take x-rays to determine the exact amount the lower jaw must be moved to keep the airway open. Adjustments are made gradually to avoid changing your bite or causing jaw discomfort.
Another treatment option is orofacial myofunctional therapy (OMT). OMT focuses on neuromuscular reeducation of oral and facial muscles through exercise and behavior modification techniques. These practices promote proper tongue placement, improve breathing, chewing and swallowing, and correct head and neck posture. OMT is particularly effective in treating mild to moderate sleep apnea and offers significant benefits.
Lifestyle Modifications to Relieve Sleep Apnea
Dysfunctioning breathing habits can interfere with your health and worsen conditions like sleep apnea. We recommend consulting with a respiratory behavior analyst to help you identify your breathing habits, what triggers them, and how to address them. This is an important step in managing sleep apnea.
In addition to proper breathing, certain lifestyle changes can significantly reduce sleep apnea symptoms, including snoring. Depending on the severity of your condition, these adjustments are often very effective.12
- Maintain a healthy weight — Obesity is a risk factor for sleep apnea. If you are overweight or obese, losing just 10% of your body weight can significantly improve your sleep apnea symptoms.
- Choose the right sleeping position — Sleeping on your back often worsens sleep apnea because the tongue and soft palate are tilted backward, blocking the airway. Instead, try sleeping on your side, stomach, or with your upper body elevated.13 To prevent your back from rolling while you sleep, try simple tricks like attaching a tennis ball to the back of your pajamas or using strategically placed pillows.
- Avoid alcohol and cigarettes — Both drinking and smoking make sleep apnea symptoms worse. Alcohol relaxes throat muscles, increasing the risk of airway obstruction, while smoking causes inflammation and fluid retention in the airways.
- Avoid benzodiazepines — These sedatives worsen sleep apnea by further relaxing the neck muscles, making airway obstruction more likely.
Embracing this knowledge can help you make informed decisions about your health, helping you enjoy a better quality of life while reducing your risk of cognitive decline. Don’t let sleep apnea quietly affect your cognitive problems. Get an evaluation and holistic treatment to protect your brain health for the future.
