Review ArticleA review of neurocognitive function and obstructive sleep apnea with or without daytime sleepiness
Introduction
Obstructive sleep apnea (OSA) is a common sleep-related breathing disorder characterized by repetitive obstruction of the upper airway, intermittent hypoxemia, and arousal from sleep with resulting sleep fragmentation [1]. Excessive daytime sleepiness (EDS) is a significant public health problem, with an estimated prevalence as high as 18% in the general population [2]. Depression, obesity, old age, and insufficient sleep are the risk factors for EDS [3]. EDS is a common complaint in patients with OSA, with daytime dysfunction, reduced quality of life, and psychological and cognitive deficits [4], [5]. The main neurocognitive impairments with OSA typically lie in three domains: (1) attention and vigilance, (2) learning and memory, and (3) executive function [6].
Sleep fragmentation or the subsequent daytime sleepiness are among the most important etiologies related to the decline of neurocognitive function (NCF) in OSA patients. Continuous positive airway pressure (CPAP) is the most efficacious and widely used medical treatment of OSA, since it improves daytime sleepiness and neurocognitive dysfunction. However, EDS is not universally present in all patients with OSA [7], and we therefore explore the following questions. What are the differences in domains of neurocognitive impairments between OSA patients with or without EDS? Is there a similar effect of therapy on cognitive dysfunction in these two groups of patients? The objective of this review is to search the literature as related to EDS, OSA, and NCF, and to summarize NCF in OSA patients with and without EDS.
Section snippets
Methods
Two authors (JZ and MC) independently searched the international literature through May 27, 2015 for articles evaluating NCF in patients with OSA, with and without EDS. Databases searched included PubMED/Medline, The Cochrane Library, and Scopus. The inclusion criteria: studies evaluating OSA patients with and without EDS (with either objective or subjective testing), who also underwent NCF testing. An example of a search performed in PubMED/Medline is: {[(sleepiness) OR (hypersomn*)] AND
Results
A total of 65 studies were included in this review. The four main study themes for this review included: (1) 16 studies describing the relationship between OSA and daytime sleepiness (see Table 1), (2) 16 studies describing the relationship between NCF and OSA with or without daytime sleepiness (see Table 2), (3) 20 studies describing the effects of CPAP treatment on sleepiness in OSA patients (see Table 3), and (4) 13 studies describing the effects of CPAP treatment on NCF in OSA patients (see
Discussion
EDS is a common symptom which can contribute to neurocognitive impairments in OSA patients. EDS is a potentially dangerous daytime symptom, which can result in the increased risk of traffic accidents and may impose a substantial burden on quality of life. Patients with OSA present with varying degrees of sleepiness and this is often one of the first symptoms that leads them to seek medical evaluation for the problem. However, in clinical practice, some patients may have no significant EDS even
Conclusions
EDS can contribute to neurocognitive deficits as well as hypoxemia in patients with OSA. A more extensive and complex neurocognitive dysfunction has been demonstrated in OSA patients with EDS; therefore, daytime sleepiness has been hypothesized to relate to the domain and extent of cognitive impairments. CPAP therapy can significantly improve the subjective daytime sleepiness and can partly reverse neurocognitive deficits in OSA patients with EDS, but fails to improve cognitive dysfunction in
Conflicts of interest
The authors declare no conflicts of interest.
The ICMJE Uniform Disclosure Form for Potential Conflicts of Interest associated with this article can be viewed by clicking on the following link: http://dx.doi.org/10.1016/j.sleep.2016.02.008.
Acknowledgements
This work was supported by the National Natural Science Foundation of China (No: 81501144, 81530002 and 81328010) and the National Basic Research Program of China (No: 2015CB856406).
References (118)
- et al.
Pathogenesis of obstructive sleep apnoea/hypopnoea syndrome
Lancet
(1994) - et al.
Cognition and daytime functioning in sleep-related breathing disorders
Prog Brain Res
(2011) - et al.
Determinants of daytime sleepiness in obstructive sleep apnea
Chest
(1988) - et al.
Predictors of objective level of daytime sleepiness in patients with sleep-related breathing disorders
Chest
(1989) - et al.
Comparing MSLT and ESS in the measurement of excessive daytime sleepiness in obstructive sleep apnoea syndrome
J Psychosom Res
(2005) - et al.
Daytime sleepiness and polysomnography in obstructive sleep apnea patients
Sleep Med
(2008) - et al.
[Clinical and cardiovascular characteristics of patients with obstructive sleep apnoeas without excessive daytime sleepiness]
Arch Bronconeumol
(2010) - et al.
Obstructive sleep apnea-hypopnea and neurocognitive functioning in the Sleep Heart Health Study
Sleep Med
(2006) - et al.
Effects of obstructive sleep apnea on cognitive function: a comparison between younger and older OSAS patients
Sleep Med
(2008) - et al.
Hypoxemia vs sleep fragmentation as cause of excessive daytime sleepiness in obstructive sleep apnea
Chest
(1991)
Daytime sleepiness after long-term continuous positive airway pressure (CPAP) treatment in obstructive sleep apnea syndrome
J Neurol Sci
Use of the Epworth Sleepiness Scale to demonstrate response to treatment with nasal continuous positive airways pressure in patients with obstructive sleep apnoea
Respir Med
Long-term effects nasal continuous positive airway pressure on daytime sleepiness, mood and traffic accidents in patients with obstructive sleep apnoea
Respir Med
CPAP improves endothelial function in minimally symptomatic OSA patients: results from a subset study of the MOSAIC trial
Chest
Neuropsychological investigations and event-related potentials in obstructive sleep apnea syndrome before and during CPAP-therapy
J Neurol Sci
Cognitive dysfunction in patients with obstructive sleep apnea (OSA): partial reversibility after continuous positive airway pressure (CPAP)
Brain Res Bull
Maintenance of wakefulness test in obstructive sleep apnea syndrome
Chest
Excessive daytime sleepiness in sleep apnea: it is not just apnea hypopnea index
Sleep Med
Cognitive impairment in patients with obstructive sleep apnea and associated hypoxemia
Chest
Sleep-related breathing disorders and continuous positive airway pressure-related changes in cognition
Sleep Medicine Clinics
Adult obstructive sleep apnea: pathophysiology and diagnosis
Chest
Sleep fragmentation reduces hippocampal CA1 pyramidal cell excitability and response to adenosine
Neurosci Lett
Prevalence and risk factors of subjective sleepiness in the general adult population
Sleep
Excessive daytime sleepiness in sleep disorders
J Thorac Dis
Multiple naps and the evaluation of daytime sleepiness in patients with upper airway sleep apnea
Sleep
Neuropsychological dysfunction in sleep apnea
Sleep
The occurrence of sleep-disordered breathing among middle-aged adults
N Engl J Med
Obstructive sleep apnea: factors important for severe daytime sleepiness]
Medicina (Kaunas)
Sleepiness in patients with moderate to severe sleep-disordered breathing
Sleep
Inflammatory proteins in patients with obstructive sleep apnea with and without daytime sleepiness
Sleep Breath
Daytime sleepiness and polysomnographic variables in sleep apnoea patients
Eur Respir J
Severe obstructive sleep apnea: sleepy versus nonsleepy patients
Laryngoscope
Sleepiness in patients with obstructive sleep apnoea – daytime course and impact of nocturnal respiratory events
Neuro Endocrinol Lett
Correlation between hippocampal volume and excessive daytime sleepiness in obstructive sleep apnea syndrome
Eur Rev Med Pharmacol Sci
Nocturnal hypoxemia biomarker predicts sleepiness in patients with severe obstructive sleep apnea
Sleep Breath
Subjective sleepiness and daytime functioning in bariatric patients with obstructive sleep apnea
Sleep Breath
Factors associated with excessive daytime sleepiness in patients with severe obstructive sleep apnea
Sleep Breath
Clinical and polysomnographic differences between OSAH patients with/without excessive daytime sleepiness
Sleep Breath
Obstructive sleep apnea syndrome: pathogenesis of neuropsychological deficits
J Clin Exp Neuropsychol
Sleep apnea and vigilance performance in a community-dwelling older sample
Sleep
Deficits of cognitive executive functions in patients with sleep apnea syndrome
Sleep
Sleep-disordered breathing and neuropsychological deficits. A population-based study
Am J Respir Crit Care Med
Measures of cognitive function in persons with varying degrees of sleep-disordered breathing: the Sleep Heart Health Study
J Sleep Res
Procedural skill learning in obstructive sleep apnea syndrome
Sleep
Comparison of cognitive performance among different age groups in patients with obstructive sleep apnea
Sleep Breath
Pattern & correlates of neurocognitive dysfunction in Asian Indian adults with severe obstructive sleep apnoea
Indian J Med Res
Obstructive sleep apnea syndrome is associated with deficits in verbal but not visual memory
Am J Respir Crit Care Med
The association between obstructive sleep apnea and neurocognitive performance – the Apnea Positive Pressure Long-term Efficacy Study (APPLES)
Sleep
Neuropsychological function in mild sleep-disordered breathing
Sleep
Executive functions in persons with sleep apnea
Sleep Breath
Cited by (0)
Disclaimer: The views herein are the private views of the authors and do not reflect the official views of the Department of the Army or the Department of Defense.