Key points
Obstructive sleep apnea (OSA) is the world’s most common sleep-related breathing disorder.
Individuals with OSA are at an increased risk of anxiety, depression, and cognitive impairment.
Among men in their 50s, OSA is associated with a 6-fold increase in risk of cognitive impairment.
Clinicians should always inquire into patients’ sleep health to determine if OSA is contributing to symptoms.
Clinical diagnostic work is very similar to detective work. During the initial evaluation of the patient, we gather evidence from signs and symptoms, inquire into potential connections that may not be obvious to the untrained eye, and then use our medical knowledge to form a hypothesis and recommend treatments.
It is rare that patients’ signs and symptoms perfectly match the textbook definition of a disorder. More likely, they will fixate on a few symptoms but fail to mention others because they don’t think they are relevant. Knowing how to ask the right questions ensures these clues don’t go unmentioned.
For clinical psychiatrists, a key part of every interview should center on the subject of sleep. While hypersomnia tends to be associated with major depressive episodes, insomnia is associated with far too many disorders to name, and most clinicians recognize that it is a good indication that the patient may be experiencing psychological distress.
However, one type of sleep disorder that regularly escapes clinicians’ observation is obstructive sleep apnea. Recent research has shown that OSA is an independent risk factor for depression, anxiety, and more importantly cognitive decline/dementia, which is why it is vital that clinicians always ask their patients if they have been diagnosed with OSA or if they have some of the symptoms associated with the disorder.
Obstructive Sleep Apnea at a Glance
Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder in the world. It is estimated that 39 million adults in the United States have OSA and that the global figure is as high as 936 million. Risk factors for OSA include obesity, older age, male sex, a history of alcohol or tobacco use, a family history of OSA, and structural abnormalities in the throat or neck.
OSA occurs when the throat muscles relax during sleep, leading to an interruption in the flow of air through the nose or mouth. The cessation in airflow is jarring enough to rouse a person from sleep so that they can reopen their airway, but the arousal is so brief that it does not get stored in memory. Patients with mild OSA tend to experience between five and ten apneic episodes per hour of sleep. In extreme cases, patients may experience over 30 episodes per hour.
As far too many spouses know, the main symptoms of OSA are loud snoring with intervals where breathing ostensibly stops for a few seconds before resuming. In some cases, it can sound like the individual is choking. Patients with OSA tend to experience daytime sleepiness, fatigue, morning headaches, morning confusion, and decreased libido. Patients with OSA are also at an increased risk of medical problems, such as cardiac arrhythmias, hypertension, and metabolic syndrome.
Evidence of Correlation
The simple explanation for the association between psychiatric disorders and OSA is that our brain needs sleep to function properly. While most people need between seven and nine hours each night for optimal health, no one is going to develop a psychiatric disorder by sacrificing a few hours of sleep every once in a while. However, when one’s sleep is regularly disrupted due to OSA, there is a cumulative effect.
A cross-sectional study from 2003 involving almost 19,000 participants revealed that patients with major depressive disorder are five times more likely to have OSA. Meanwhile, a 2023 study involving just under 10,000 individuals found that patients with OSA are 1.36-fold more likely to experience depression and that the severity of OSA positively correlates with depressive symptoms. A systematic review and meta-analysis published in 2020 showed a notably high presence of both depressive and anxiety symptoms among individuals with OSA—35 percent and 32 percent, respectively.
A similar correlation is evident with respect to mild cognitive impairment and dementia. Older patients with OSA appear to be at a higher risk of both, with one study finding a 1.7-fold increase in risk among all participants. The risk was more pronounced among men with OSA in their 50s and women with OSA aged 70 years or older. The risk of impairment was found to be 6-fold greater and 3.2-fold greater, respectively.
Potential Mechanisms
Broadly speaking, research has indicated that these disorders can be traced back to two mechanisms: sleep fragmentation and intermittent hypoxia. Sleep fragmentation leads to increases in sympathetic nervous system activity, oxidative stress, and neuroinflammation. Sleep fragmentation also leads to decreases in vasomotor reactivity.
Intermittent hypoxia occurs when patients with OSA are momentarily (but repeatedly) starved of oxygen over the course of the night. This can accelerate cerebral small vessel disease, leading to hypoperfusion (i.e., a lack of nutrients to an organ; in this case the brain), white matter integrity anomalies, gray matter loss, increased permeability of the blood-brain barrier, and neuroinflammation.
These interrelated processes compound one another, resulting in neuronal damage, neurodegenerative processes, vascular depression, and cognitive impairment.
Treating OSA
The first line of treatment in obese patients with mild symptoms or only recently developed OSA should be lifestyle interventions with a combination of dietary changes and increases in physical activity, which should make them less prone to apneic episodes. In cases where an intervention is more urgent, continuous positive airway pressure (CPAP) can open breathing passages and prevent apneic episodes. If a specific abnormality of the upper airway is found, surgical intervention can take place.
Special consideration should be given to older patients, as they are already at a greater risk of cognitive impairment and dementia—especially given the fact that obesity rates among seniors have nearly doubled within a generation. Screening for and treating OSA—as well as other sleep disturbances—can help stem neurodegeneration and decline.
The important takeaway is that OSA can cause significant complications but that it is treatable. As clinicians, we need to take a more proactive approach to treating OSA in high-risk populations because it has the potential to balloon into a major public health problem.
However, one problem is that proper sleep studies are rarely covered by insurance, making it difficult to formally diagnose OSA and obtain CPAP machines with the help of insurance. To provide symptom relief to patients who possibly have OSA, clinicians can encourage lifestyle modifications like those noted above. These changes carry no risk and involve no expensive devices, but still reduce the severity of OSA and improve patient quality of life.
Note: This article originally appeared on Psychology Today.
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