Obstructive Sleep Apnea Linked to Defect in Brain Morphology

A study has found that patients suffering from obstructive sleep apnea (OSA) have lost gray matter from areas in the brain that regulate breathing and speech, suggesting that this nighttime breathing disorder may arise from a pre-existing defect in brain morphology. The study was published in the November 15, 2002, issue of the American Journal of Respiratory and Critical Care Medicine.

Investigators from the University of California, Los Angeles (USA) used magnetic resonance imaging (MRI) to compare brain structures of 21 men who had been diagnosed with sleep apnea to 21 men who did not suffer from the disorder. Both sets of men were matched for age and weight. Factors such as severity of the disease, tobacco use, hypertension, cardiovascular health and left- or right-handedness were taken into consideration.

Evaluation of the MRI scans revealed gray matter loss in the brains of the men with sleep apnea. The tissue loss occurred primarily in regions of the brain that control speech production, movement, and emotion. The amount of brain damage directly correlated to the severity of the patient's disorder. The healthy men's brains ranged from 2% to 18% larger in these areas than the men with sleep apnea.

"For decades, we have blamed sleep apnea solely on a narrowed airway caused by enlarged tonsils, a small jaw, or excess fat in the throat,” said senior author Dr. Ronald Harper, professor of neurobiology at the David Geffen School of Medicine at UCLA. "Our findings show, however, that sleep apnea patients also suffer disordered wiring in brain regions that control muscles of the airway. These glitches may lead to the syndrome, which is exacerbated by a small airway. Our findings suggest that sleep apnea is a pre-existing condition and that abnormal brain wiring from childhood contributes to the onset of the disorder in adulthood. The evidence in the brain is very specific.”



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