Elsevier

Sleep Medicine

Volume 72, August 2020, Pages 50-58
Sleep Medicine

Review Article
Obstructive sleep apnea, depression and cognitive impairment

https://doi.org/10.1016/j.sleep.2020.03.017Get rights and content

Highlights

  • Narrative review examines the relationship between OSAS, depressive and cognitive symptoms and effect of OSAS treatment on psychiatric symptoms.

  • Depressive anxious and OSA symptoms significantly overlap.

  • Attention working memory, episodic memory and executive functions are decreased in OSA.

Abstract

Objective

Obstructive sleep apnea (OSA) is a severe disorder with a high prevalence. Psychiatric comorbidities, especially depressive symptoms and cognitive dysfunction, are often described in OSA patients. This narrative review aims to examine: (1) the relationship between obstructive sleep apnea syndrome (OSAS) and depressive and cognitive symptoms, and (2) the effect of OSAS treatment on psychiatric symptoms.

Method

Articles that were published between January 1990 and August 2018 were searched and extracted via PubMed, and Web of Science databases. Authors analyzed the papers and its references using the following keywords: obstructive sleep apnea, depression, cognitive dysfunction, anxiety disorders, and continuous positive airway pressure (CPAP). A total of 632 articles were nominated. After the selection according to the inclusion and exclusion criteria, 172 articles were chosen. After complete inspection of the full texts, finally, 58 papers were selected. Secondary papers from the reference lists of the primarily designated papers were also searched, assessed for suitability, and added to the first list of the papers (n = 67). In total, 125 papers were included in this review.

Results

There is a significant overlap in depressive, anxious and OSA symptoms. Studies also show that attention, working memory, episodic memory, and executive functions are decreased in OSA. Conversely, most of verbal functions remain intact and variable results are found in psychomotor speed. Several studies implicated that in some fields of cognitive functions (eg, attention) deficit caused by untreated OSA can be irreversible and shows only partial recovery after a period of treatment with CPAP.

Conclusions

Untreated OSA impacts affective disorders, and often leads to decline of cognitive functions or even leads to permanent brain damage. Further studies are needed to analyze the connection between OSA and affective disorders, anxiety disorders and its effect on cognitive functions more thoroughly, especially in the context of CPAP treatment.

Introduction

Obstructive sleep apnea (OSA) has been classified as a sleep breathing disorder which contributes to oxidative stress. OSA occurs in at least 10% of the population, and leads to higher morbidity and mortality; nevertheless, associations between OSA severity and psychological or psychiatric problems remain unclear. OSA is characterized by repeated cessation or significant restrictions of airflow (apnea and hypopnea) present in sleep accompanied by oxygen desaturation and arousals [1]. Currently, it is the most common sleep disorder of breathing [1,2]. Craniofacial disharmony is a central risk aspect for the OSA [3]. The fatty accumulation in the pharynx may have a role in some very obese individuals [3]. The most OSA is linked to a narrow high-arched hard palate and mid-face hypoplasia with retro-positioning of the maxilla and chin (bringing the soft palate and tongue closer to the back of the throat [4]). The structural disproportions among the skeletal craniofacial and soft tissue structures disturb pharyngeal airway morphology in OSA patients. The proportions of the nasopharynx, pharyngeal length, and the cross-sectional area at the hard palate level, were linked with the severity of OSA [5].

Although (hetero) anamnestic information may be collected to determine the diagnosis of OSA, apnea hypopnea index (AHI) polysomnography (PSG) is a gold standard for proper diagnosis. AHI refers to the number of apnea or hypopnea episodes recorded per hour of sleep. An AHI of 5–14 indicates mild, 15–30 moderate and ≥30 severe OSA. Hypopnea and apnea interrupt deep sleep and rapid eye movements (REM) phase and cause sleep pattern fragmentation [6]. After awakening, patients do not feel relaxed and remain tired during the day. Night time symptoms include snoring, breathing breaks, feeling sick, excessive salivation, excessive sweating, gastroesophageal reflux, urination during the night, dry mouth and headache [7,8]. Day time symptoms include excessive sleepiness, loss of energy, irritability [9], withdrawal from social activities, difficulty in concentrating [10], cognitive dysfunction [11,12], anxiety or depressive mood problems [13], and psychomotor changes [9,14]. These symptoms show a marked similarity to the symptoms of major depressive disorder [15,16]. Up to 63% of patients with OSA have depressive symptoms [13,16,17]. Therefore, many sleep laboratories regularly evaluate the depressive symptoms of their patients using screening questionnaires [8]. The similarity in the phenotypic expression of OSA and depressive disorders may lead to misdiagnosing sleep apnea for depressive disorder and misuse of antidepressant therapy [18,19]. Diagnostics is performed in sleep laboratories. The most effective treatment is considered to be positive airway pressure (PAP) treatment – the most common mode of therapy is continuous positive airway pressure (CPAP) derived via different types of masks [[20], [21], [22]]. Surgical treatment might be efficient in some cases, especially in mild to moderate OSA in non-obese patients [5].

The prevalence of OSA in adults (39–59 years) is estimated to be between 2% and 14%, but in individuals with age over 60 years it is as high as 20% [2,23,24]. A critical epidemiological analysis of limited home polysomnography in the United States showed that the prevalence of OSA, defined by AHI > 15, was approximately 18% in the general population [25]. OSA significantly reduces the quality of life (QoL) [22,24]. It is also a risk factor for other health problems such as increased prevalence of cardiovascular diseases, hypertension, sudden death, and psychiatric conditions like depression, irritability, memory and cognitive impairment [[24], [25], [26], [27], [28]]. Many studies have confirmed that obesity, age, sex, snoring, pharyngeal anatomy abnormalities, and cephalometric characteristics may be risk factors for OSA [5,29,30].

In the literature, OSA is discussed as possible comorbidity of affective and cognitive disorders [[31], [32], [33]]. When unrecognized, OSA may worsen the symptoms of psychiatric disorders and prevent achieving of remission [32]. OSA is often considered and diagnosed late, even when snoring and apneas are noticed by medical staff. Studies combining untreated OSA with range of psychiatric disorders have emerged [34,35]. Recently, several studies connected untreated obstructive sleep apnea with a range of psychiatric disorders [[36], [37], [38], [39]]. This confirms that comorbid OSA may worsen symptoms of affective disorders. OSA shares many symptoms with depression (concentration disturbances, energy loss, and increased fatigue) and leads to the deepening of depressive symptomatology and the development of cognitive deficits [32,[38], [39], [40], [41]]. Untreated comorbid OSA leads to poor adherence to drug therapy, and in contrary, treatment of OSA improves the symptoms of depression [40,[42], [43], [44]].

Due to the contraindication of hypnotics and benzodiazepines in OSA, initial depressive treatment periods with polypharmacy may lead to a rapid worsening of OSA symptoms [45]. However, this contraindication can be minimized by using CPAP therapy during the period of sleep in severe depressive disorders.

The aim of the narrative review is to examine: (1) the relationship between OSAS and depressive and cognitive symptoms, and (2) the effect of OSAS treatment on psychiatric symptoms.

Section snippets

Method

Articles were acquired via PubMed and Web of Science published in the years between January 1990 and August 2018 were extracted. This article is narrative review, which describes and discusses the state of the knowledge of a topic of the OSA relation to psychiatric and cognitive problems from the contextual point of view. It consists of the critical examination of the literature published in PubMed, and Web of Science. Authors made a series of literature searches using the following keywords or

Depression in patients with OSA

Psychiatric comorbidities, especially depressive symptoms or depressive disorders, are often described in OSA patients [26,47]. Concerning emotional well-being, the disturbed sleep pattern negatively affects the stress system and thus increases the susceptibility of OSA individuals to depression [[47], [48], [49]]. The study of Kang et al. [50], revealed damages at insular cortex with correlation to symptoms of depression and anxiety (Hamilton depression scale and Hamilton anxiety scale) in OSA

Discussion

Our review article points out that patients with OSA can also suffer from additional problems, particularly higher depression and anxiety scores and diminished cognitive functions. It is essential to differentiate whether the depression score is connected to the OSA itself, or whether it rather is a manifestation of a comorbid depression disorder. Numerous findings concerning the psychiatric problems in OSA patients have been reported, however, their importance needs to be explored further, as

Conclusion

OSA is a severe illness that has a high prevalence in the adult population and will most likely continue to increase in the future due to the trend of increasing the average weight. In our conditions, sleep apnea is usually diagnosed too late, and despite repeated observations of typical night-time symptoms in inpatient care, clinicians rarely consider it. Untreated OSA worsens many cardiovascular diseases, prevents their compensation, impacts affective disorders, and often leads to worsening

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