What causes Obstructive Sleep Apnea (OSA)?

From the Guidelines

Obstructive sleep apnea (OSA) is caused by a combination of factors, including anatomical characteristics, functional traits, age, sex, body mass index (BMI), and lifestyle, with the most recent estimates suggesting that approximately 1 billion adults worldwide are affected 1. The causes of OSA can be broken down into several key categories, including:

• Genetics: playing a role in the development of OSA, although the exact mechanisms are not fully understood 1
• Anatomical characteristics: such as a narrow upper airway, abnormalities in craniofacial structure, and other physical features that can increase the risk of airway obstruction 1
• Functional traits: including airway collapsibility, upper airway muscle responsiveness, arousability, and breathing instability, which can all contribute to the development of OSA 1
• Age and sex: with OSA being more common in older adults and males, although the exact reasons for this are not fully understood 1
• Body mass index (BMI): with excess weight being a major risk factor for OSA, as it can increase the amount of fat around the neck and narrow the airway 1
• Lifestyle: including factors such as smoking, alcohol consumption, and physical inactivity, which can all increase the risk of developing OSA 1 It is essential to address these modifiable risk factors to improve OSA symptoms and reduce the risk of associated morbidity and mortality. Some of the key takeaways from the study include:
• The importance of identifying and addressing anatomical and functional traits that contribute to OSA 1
• The need to consider lifestyle factors, such as smoking and alcohol consumption, when assessing and managing OSA 1
• The potential benefits of weight loss and other lifestyle modifications in improving OSA symptoms and reducing the risk of associated health problems 1

From the Research

Causes of OSA

• Obstructive sleep apnea (OSA) is a disease that results from loss of upper airway muscle tone leading to upper airway collapse during sleep in anatomically susceptible persons 2
• The major risk factors for the disorder include obesity, male gender, and age 3
• OSA develops in the presence of both elevated mechanical loads on the upper airway and defects in compensatory neuromuscular responses 3
• Chronic intermittent hypoxia, sleep fragmentation, and inflammatory activation are the main pathophysiological mechanisms of OSA 4

Risk Factors

• Obesity is a major risk factor for OSA, and the public health burden from OSA and its sequalae are expected to increase with escalating rates of obesity 2
• Male gender and age are also significant risk factors for the development of OSA 3
• OSA is highly prevalent in obese patients and may contribute to cardiometabolic risk by exerting detrimental effects on adipose tissue metabolism and potentiating the adipose tissue dysfunction typically found in obesity 4

Pathophysiology

• The balance of anatomically imposed mechanical loads and compensatory neuromuscular responses are important in maintaining upper airway patency during sleep 3
• Upper airway collapse during sleep is the main characteristic of OSA, leading to recurrent periods of hypoventilation, hypoxia, and arousals from sleep 2
• The neural control of the striated muscles that control the pharyngeal passages, especially regulation of hypoglossal motoneuron activity throughout the sleep/wake cycle, plays a crucial role in the development of OSA 2