In sleep apnea, a sleeper's breathing is halted as the airway is blocked by muscle and other tissue. The condition is characterized by loud bursts of snoring and chronic fatigue. The researchers suggest early diagnosis and treatment of sleep apnea may help forestall memory loss.
"Our findings demonstrate that impaired breathing during sleep can lead to a serious brain injury that disrupts memory and thinking," principal investigator Ronald Harper of the David Geffen School of Medicine at the University of California, Los Angeles said in a statement.
The researchers used magnetic resonance imaging to collect high-resolution images of the brains of 43 sleep apnea patients, including slices of the mammillary bodies -- named because they resemble small breasts on the underside of the brain -- and compared the results to images of 66 controls matched for age and gender.
The study, published in the journal Neuroscience Letters, found sleep apnea patients' mammillary bodies were nearly 20 percent smaller.
"The findings are important because patients suffering memory loss from other syndromes, such as alcoholism or Alzheimer disease, also show shrunken mammillary bodies," study lead author Rajesh Kumar said.