Sleep apnea is a respiratory disorder manifested during sleep that involves episodes in which a person misses one or more breath at a time. The disorder is usually experienced in several episodes during the night and triggers fatigue and sleepiness during the day. Snoring and restless sleep are also symptoms associated with sleep apnea. According to a new study carried out at the University of California, five or more episodes per hour may have serious consequences on the brain tissue and can lead to problems related to memory recognition.

High-resolution images made through a magnetic resonance imaging process on about forty patients revealed that parts of the brain known as the mammillary bodies, that are located in the anterior end of the archer of the fornix and are responsible for processing memories, are about 20 percent smaller than those of people that don't have sleep apnea.

"OSA patients showed significantly reduced left, right, and combined mammillary body volumes compared with control subjects, after partitioning for age, gender, and head size. Left-side mammillary bodies showed greater volume reduction than the right side. Obstructive sleep apnea (OSA) patients show compromised emotional and cognitive functions, including anterograde memory deficits," reads the abstract of the study conducted by neurobiologist Ronald Harper of the University of California.

"Our findings demonstrate that impaired breathing during sleep can lead to a serious brain injury that disrupts memory and thinking," said Harper in an interview.

According to the results of the study, the decrease in the mammillary body volume in patients suffering from obstructive sleep apnea is not only affecting memory but also spatial orientation. However, the mechanism through which the volume of the respective area of the brain is affected is unknown, but is probably associated with hypoxic/ischemic processes and nutritional deficiencies.

"The findings are important because patients suffering memory loss from other syndromes, such as alcoholism or Alzheimer disease, also show shrunken mammillary bodies," said Rahesh Kumar, a member of the research team.

Patients with sleep apnea disorder are rarely aware of their problems and are generally informed by their partners that are awaken during a sleep apnea episode. Some of the most serious consequences of this disorder can go as far as cor pulmonale or heart failure.