title: The impact of sleep and hypoxia on the brain: potential mechanisms for the effects of obstructive sleep apnea.
abstract: OBJECTIVE
  Obstructive sleep apnea (OSA) is a chronic, highly prevalent, multisystem disease, which is still largely underdiagnosed. Its most prominent risk factors, obesity and older age, are on the rise, and its prevalence is expected to grow further. The last few years have seen an exponential increase in studies to determine the impact of OSA on the central nervous system. OSA-induced brain injury is now a recognized clinical entity, although its possible dual relationship with several other neuropsychiatric and neurodegenerative disorders is debated. The putative neuromechanisms behind some of the effects of OSA on the central nervous system are discussed in this review, focusing on the nocturnal intermittent hypoxia and sleep fragmentation.
  
  
  RESULTS
  Recent preclinical and clinical findings suggest that neurogenic ischemic preconditioning occurs in some OSA patients, and that it may partly explain variability in clinical findings to date. However, the distinct parameters of the interplay between ischemic preconditioning, neuroinflammation, sleep fragmentation and cerebrovascular changes in OSA-induced brain injury are still largely unclear, and more research is required.
  
  
  CONCLUSIONS
  Early diagnosis and intervention in patients with OSA is of paramount importance. Future clinical studies should utilize multimodal investigative approaches to enable more reliable referencing for the acuity of the pathological process, as well as its reversibility following the treatment.
authors.affiliation: aSleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, King's College and Imperial College London, UK bDanish Epilepsy Centre, Dianalund, Denmark cAcademic Unit of Sleep and Breathing, National Heart and Lung Institute, Imperial College London dNIHR Respiratory Disease Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK.
authors.forename: Ivana
authors.initials: I
authors.lastname: Rosenzweig
authors.forename: Steve C R
authors.initials: SC
authors.lastname: Williams
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Morrell
mesh_terms: D000375:Aging; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D042241:Early Diagnosis; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D019194:Ischemic Preconditioning; D009473:Neuronal Plasticity; D015995:Prevalence; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*; D012892:Sleep Deprivation / Q000150:complications / Q000378:metabolism / Q000503:physiopathology*