Associations between brain white matter integrity and disease severity in obstructive sleep apnea.
Obstructive sleep apnea (OSA) is characterized by recurrent upper airway blockage, with continued diaphragmatic efforts to breathe during sleep. Brain structural changes in OSA appear in various regions, including white matter sites that mediate autonomic, mood, cognitive, and respiratory control. However, the relationships between brain white matter changes and disease severity in OSA are unclear. This study examines associations between an index of tissue integrity, magnetization transfer (MT) ratio values (which show MT between free and proton pools associated with tissue membranes and macromolecules), and disease severity (apnea-hypopnea index [AHI]) in OSA subjects. We collected whole-brain MT imaging data from 19 newly diagnosed, treatment-naïve OSA subjects (50.4 ± 8.6 years of age, 13 males, AHI 39.7 ± 24.3 events/hr], using a 3.0-Tesla MRI scanner. With these data, whole-brain MT ratio maps were calculated, normalized to common space, smoothed, and correlated with AHI scores by using partial correlation analyses (covariates, age and gender; P < 0.005). Multiple brain sites in OSA subjects, including superior and inferior frontal regions, ventral medial prefrontal cortex and nearby white matter, midfrontal white matter, insula, cingulate and cingulum bundle, internal and external capsules, caudate nuclei and putamen, basal forebrain, hypothalamus, corpus callosum, and temporal regions, showed principally lateralized negative correlations (P < 0.005). These regions showed significant correlations even with correction for multiple comparisons (cluster-level, family-wise error, P < 0.05), except for a few superior frontal areas. Predominantly negative correlations emerged between local MT values and OSA disease severity, indicating potential usefulness of MT imaging for examining the OSA condition. These findings indicate that OSA severity plays a significant role in white matter injury. © 2016 Wiley Periodicals, Inc.
Department of Anesthesiology, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Sudhakar
S
Tummala
UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Bhaswati
B
Roy
Department of Anesthesiology, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Bumhee
B
Park
Department of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Daniel W
DW
Kang
UCLA School of Nursing, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Mary A
MA
Woo
Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA 90095, USA.|Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Ronald M
RM
Harper
Department of Anesthesiology, University of California at Los Angeles, Los Angeles, CA 90095, USA.|Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA.|Department of Radiological Sciences, University of California at Los Angeles, Los Angeles, CA 90095, USA.|Department of Bioengineering, University of California at Los Angeles, Los Angeles, CA 90095, USA.
Rajesh
R
Kumar
D000328:Adult; D000342:Affective Symptoms / Q000000981:diagnostic imaging / Q000209:etiology; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D017286:Polysomnography; D011569:Psychiatric Status Rating Scales; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D066127:White Matter / Q000000981:diagnostic imaging*
apnea-hypopnea index; frontal white matter; hypoxia; insula; magnetization transfer imaging