The relationships between obstructive sleep apnea and psychiatric disorders: a narrative review

Abstract Introduction: Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder. Its prevalence tends to increase worldwide. Untreated sleep apnea is associated with a higher risk of metabolic diseases, cardiovascular diseases, stroke, road accidents, and death, but also it is suggested that it increases the risk of mental disorders. Method: The literature review was based on a search of articles on Medline, Pubmed, and Google Scholar from 2003 to 2021 using the keywords: obstructive sleep apnea; mental disorders; cognitive functions; affective disorders; depression; bipolar disorder; schizophrenia; psychotic disorders. The analysis included original studies, meta-analysis, and review articles. Discussion: The result obtained from researches published so far does not allow for drawing unequivocal conclusions. There is a lot of bias present in study protocols and inclusion/exclusion criteria. Nonetheless, it seems that some disorders have a better proven correlation with OSA. Cognitive impairment, depression, and anxiety disorders are linked to OSA not only in terms of the overlapping of symptoms but also of a causal relationship. Psychotic disorders and bipolar disorders connections with OSA are confirmed, but they are not yet well understood. All correlations are found to be possibly bidirectional. Conclusion: 1. Multiple lines of evidence increasingly point towards a bidirectional connection between OSA and mental disorders, and the cause and effect relationship between these two groups of disorders requires further research. 2. Due to reports of an increased risk of OSA with antipsychotic drugs, caution should be exercised when initiating therapy with this type of drug in patients with known risk factors for it. 3. Screening for OSA in psychiatric patients should be introduced as OSA can increase cognitive impairment, affective, and psychotic symptoms.