WASHINGTON — Stuttering and a serious form of snoring known as sleep apnea may be linked, and both conditions may be caused by brain damage sustained early in life, U.S. researchers said Monday.
A team at UCLA found that nearly 40% of sleep apnea patients it studied also stuttered as children.
Sleep apnea is a serious form of snoring in which a patient's breathing actually stops several times a night. It is linked with a high rate of heart death.
"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," Ronald M. Harper, a professor of neurobiology who led the study, said in a statement.
"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."
Writing in the American Journal of Respiratory and Critical Care Medicine, Harper and his colleagues said they used magnetic resonance imaging to compare the brains of 21 men diagnosed with sleep apnea with 21 men free of the disorder.
The MRIs revealed a dramatic loss of gray matter -- brain cells -- in the men with sleep apnea. The worst-hit areas were those involved in speech production, movement and emotion.
The amount of brain damage correlated directly to the severity of sleep apnea. The healthy men's brains were 2% to 18% 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. This, in turn, eventually leads to sleep apnea," said Paul Macey, who also worked on the study.
"Because the sleep apnea patients possessed speech impairments from childhood, and their brain's speech center revealed significant gray matter loss, this brain damage likely originated early in life."
The researchers said that 38% of the sleep apnea patients reported a history of stuttering or speech impairment. Overall, 7% of the general population stutters.
"Speech impediments may prove an important diagnostic clue for assessing and treating sleep apnea," Macey added. "In the future, doctors may monitor certain brain structures and examine children for speech or movement problems that may predict a higher sleep apnea risk."