title: Association between high nocturnal blood pressure and white matter change and its interaction by obstructive sleep apnoea among normotensive adults.
abstract: OBJECTIVE
  A reverse dipping pattern, characterized by higher night-time blood pressure (BP) than daytime BP, is associated with the increased risk for cerebrovascular disease, cardiovascular events and all-cause mortality. However, little has known about the association between white matter change (WMC) and reverse dipping pattern, particularly in normotensive adults. We aimed to examine whether WMC is associated with BP dipping patterns as measured with a 24-h ambulatory BP monitoring and whether obstructive sleep apnoea (OSA) is involved in this relationship
  
  
  METHODS
  : A total of 703 normotensive adults were from an ongoing longitudinal study in a general population. WMC was measured with brain MRI. BP dipping patterns were defined as the ratio of the change in night-time and daytime SBP. OSA was categorized with the apnoea-hypopnea index, as measured with polysomnography. To avoid the influence of hypertensive medications, we only included normotensive adults for the final analysis. To examine the associations between WMC and dipping patterns, we built logistic models. To elucidate the role of OSA, we also conducted both modification and mediation tests.
  
  
  RESULTS
  Reverse dipping pattern was significantly associated with WMC (odds ratio 1.49, 95% confidence interval 1.02-2.18). Further, OSA modified the association between dipping patterns and WMC (P = 0.0118). No mediation effect of OSA was assessed.
  
  
  CONCLUSIONS
  In 703 normotensive adults, the reverse dipping pattern showed a significant association with WMC, after adjusting for covariates. Further, according to the presence of OSA, the association between reverse dipping and WMC was varied.
authors.affiliation: aInstitute of Human Genomic Study, School of Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea bDepartment of Medicine, Division of Pulmonary, Critical care & Sleep, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA cDepartment of Radiology, School of Medicine, Korea University, Ansan Hospital, Ansan dDepartment of Foods and Nutrition, College of Natural Sciences, Kookmin University, Seoul eDivision of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam fDivision of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University, Ansan Hospital, Ansan, Republic of Korea.
authors.forename: Sunghee
authors.initials: S
authors.lastname: Lee
authors.forename: Robert Joseph
authors.initials: RJ
authors.lastname: Thomas
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.forename: Hyung Suk
authors.initials: HS
authors.lastname: Seo
authors.forename: Inkyung
authors.initials: I
authors.lastname: Baik
authors.forename: Dae Wui
authors.initials: DW
authors.lastname: Yoon
authors.forename: Se Joong
authors.initials: SJ
authors.lastname: Kim
authors.forename: Seung Ku
authors.initials: SK
authors.lastname: Lee
authors.forename: Chol
authors.initials: C
authors.lastname: Shin
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D016015:Logistic Models; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D066127:White Matter / Q000473:pathology*