Sleep Apnea Linked To Early Brain Damage

"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 Dr. Ronald Harper, principal investigator and 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."

Harper's team 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. Then they weighed their findings against a template derived from 152 normal MRI scans obtained from the Montreal Neurological Institute.

Both sets of men were matched for age and weight. The researchers also considered the effects of disease severity, tobacco use, hypertension, cardiovascular health and whether the men were left- or right-handed in their comparison.

The MRIs revealed dramatic gray matter loss in the brains of the men with sleep apnea. Curiously, 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 percent to 18 percent larger in these areas than the men with sleep apnea.

"We propose that early damage to the brain's speech center triggers problems in the muscles that control the airway," said Dr. Paul Macey, first author and assistant researcher of neurobiology at the David Geffen School of Medicine at UCLA. "This, in turn, eventually leads to sleep apnea."

"Our findings suggest this sleep apnea is a pre-existing condition -- that abnormal brain wiring from childhood contributes to the onset of the disorder in adulthood," Harper said. "The evidence in the brain is very specific."

Harper noted that obstructive sleep apnea patients often display other traits that suggest subtle brain damage, including problems with memory, thought and motor skills. "The repeated oxygen loss from sleep apnea may damage other brain structures that regulate memory and thinking," he said.