Vitale et al. J Sleep Disord Manag 2016, 2:008 Volume 2 | Issue 1 Journal of Sleep Disorders and Management Review Article: Open Access Sleep Apnea and the Brain: Neurocognitive and Emotional Considerations Gregory John Vitale*, Kimberly Capp, Kimberly Ethridge, Maggie S. Lorenzetti, Mary Jef- frey, John Skicki and Ashley Stripling College of Psychology, Nova Southeastern University, Florida, USA *Corresponding author: Gregory John Vitale, College of Psychology, Nova Southeastern University, 3301 College Ave., Fort Lauderdale, Florida, 33314, USA, Tel: 9548298479, E-mail: [email protected] by utilizing a sleep diagnosis tool, called a polysomnography, to rule Abstract out other sleep disturbances and determine an individual’s apnea- Sleep apnea research has become increasingly relevant to the hypopnea index (AHI). The AHI is based on the number of apnea/ field of psychology. Although the physiological sequelae have hypopnea episodes that occur during a one-hour period of sleep been researched extensively, and treatment options are now and is used to indicate severity of the disorder. An AHI above 5 available for those diagnosed, much is left to be done. Specifically, but less than 15 is considered to be in the mild and impacts 3-28% to date, the cognitive and psychological consequences of sleep apnea have received less attention. As such, this paper serves of individuals, while an AHI above 15 is considered moderate and to review the current state of the literature and presents relevant impacts 1-14% of individuals [1]. Cases of 30 or more episodes per neuropsychological and emotional domains. Given that sleep hour are considered severe and are almost always associated with apnea may cause psychological dysfunction over-and-above those intensified sequelae (e.g. stroke, GERD, coronary heart disease, heart expected from hypersomnia alone, the role of physiological damage failure [5-7]. in relation to these impairments will also be explored. Furthermore, a brief synopsis of established and proposed treatment options is Etiological considerations for OSA include genetic risk factors, undertaken in relation to psychological symptom expression and obesity, and upper airway anatomy. Research suggests that the cognitive performance improvement. Finally, this paper highlights apolipoprotein E4 phenotype, which also has implications as a marker areas for future inquiry and offers guidance regarding the inclusion for high cholesterol, is common in patients with sleep apnea [8]. of psychological domains in subsequent research. Additionally, patients with OSA had higher body mass indexes and higher frequency of hypertension, diabetes mellitus, and coronary Sleep Apnea and the Brain: Neurocognitive and artery disease compared to a group with non-apnea sleep disorders [9]. Prevalence rates of OSA also increase with age [1,10,11]. Emotional Considerations According to the Sleep in America 2005 Poll conducted by the Sleep apnea is a sleep-related breathing disorder characterized by National Sleep Foundation, OSA may be one of the most common upper airway obstruction during sleep, decreased oxygen saturation sleep disorders in America. Of the national poll, 26% of the in the blood, and hypercapnia [1]. Common symptoms include respondents met criteria for being at high risk of OSA [11]. The daytime sleepiness, hypertension, and possible cognitive impairment poll also revealed that high-risk individuals reported lower quality [2,3]. Obstructive sleep apnea (OSA), the most common subtype, of life. Given such a large percentage of the population is affected is characterized by loud snoring, as well as, repeated slowing or by OSA, it is imperative that increased research efforts be made to suspension of breathing during sleep due to upper airway obstruction investigate etiology, symptomatology and treatment. Furthermore, it leading to anoxia. Central sleep apnea (CSA), a less common subtype, is essential that research further investigate the impact that OSA has is characterized by absence of respiratory exertion during cessations on individual cognitive and psychological functioning. Studying the of breathing due to neural feedback malfunctions between the brain negative consequences that OSA has on cognitive and psychological and the muscles controlling ventilation. While OSA and CSA are functioning is a budding area in the scientific literature with vast the main subtypes of sleep apnea, individuals can also experience a potential for clinical utility. mixed/combination type of both characteristics called complex sleep apnea syndrome [4]. Given the disparity in prevalence rates of these Brain Structural and Functional Damage conditions, the remainder of this paper will focus on the OSA subtype of sleep apnea, as it is much more common and better represented As mentioned previously, OSA is characterized by periods within the research literature. of anoxia during which the brain is restricted of oxygen. Current literature exhibits mixed results on whether periods of anoxia The diagnosis of OSA is often initiated when a family member negatively impact the brain structurally and functionally [12]. or bed partner complains of snoring and labored breathing during Research conducted by O’Donoghue et al. found no evidence that sleep, or the affected individual seeks treatment for symptoms of sleep a group of individuals with severe OSA differed significantly in gray deprivation (e.g. daytime sleepiness, morning headaches, sore or dry matter volume or focal structural changes compared to normal throat, trouble concentrating). A definitive diagnosis is established individuals using a voxel-based morphometry (VBM) technique Citation: Vitale GJ, Capp K, Ethridge K, Lorenzetti MS, Jeffrey M, et al. (2016) Sleep Apnea and the Brain: Neurocognitive and Emotional Considerations. J Sleep Disord Manag 2:008 ClinMedReceived: November 16, 2015: Accepted: February 06, 2016: Published: February 10, 2016 International Library Copyright: © 2016 Vitale GJ. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. [13]. The authors argued that research results implicating structural Executive dysfunction is correlated more with severity of changes could be attributable to comorbid conditions in the measured hypoxemia than with other symptoms of sleep apnea populations studied. However other research supports the hypothesis such as excessive daytime sleepiness; however, both can influence that anoxia negatively impacts structural and functional brain cognitive functioning to some extent [24,25]. A disruption in domains [14]. According to Beebe and Gozal, sleep disruption and executive functioning can lead to a variety of issues spanning the blood deoxygenation via OSA can attenuate the restorative process cognitive processes. Findings reported by Beebe and Gozal implicate during sleep and cause central nervous system cellular injury [15]. the prefrontal cortex as a link between the sleep disturbances Beebe and Gozal further proposed an integrative model to account experienced in sleep apnea and the cognitive deficits observed [15]. for prefrontal cortex dysfunction due to a combined sleep disruption Specifically, they propose that the hypoxemia and repeated waking and intermittent hypoxia/hypercarbia [15]. This model ultimately can damage the restoration process that occurs during sleep. It also implicates prefrontal dysfunction with a number of problematic side appears that these findings may translate to children. Halbower et al. effects including behavioral disinhibition, emotional lability, poor suggested that children (ages 6-16) with severe OSA had significant working memory, disorganization, poor judgment, and inattention. deficits in executive functioning as compared to a control group [19]. Hoth, Zimmerman, Meschede, Arnedt, & Aloia, however, Furthermore, research conducted at the Sungkyunkwan found no difference in executive functioning between a group with University School of Medicine in Seoul, South Korea suggested OSA is high hypoxemia and a group with low hypoxemia [26]. These mixed linked to specific encephalopathy in the brain [16,17]. In comparison results suggest that the hypoxemia-cognition relationship may not to same-age male healthy controls, severe OSA males showed gray be so linear, and future research is necessary to better understanding matter concentration reduction in limbic areas, cingulate gyri, these findings. prefrontal areas, caudate nuclei and the cerebellum [16]. These results were reported to be consistent with the cognitive and behavioral In addition to overall executive dysfunction, OSA patients disturbances observed in OSA patients. Interestingly, the overall also show abnormalities in attention and vigilance. Research has gray matter volume did not differ significantly between the groups, supported this hypothesis both with executive tasks that are relatively which the authors noted was consistent with the findings reported by short and in studies with children suffering from sleep disordered O’Donoghue et al. and Joo et al. further researched the connection breathing (SDB) [15]. Generally, SDB ranges in severity and includes between OSA and brain pathophysiology and found overall and snoring and obstructive sleep apnea, both of which have been localized cortical thinning in severe OSA individuals [13,17]. shown to negatively impact children’s attention,