Brain Structure in Obstructive Sleep Apnea

Sleep Disorders

Brain Structure in Obstructive Sleep Apnea

Improved neuroimaging techniques reveal extensive white-matter changes in patients with untreated obstructive sleep apnea.

Obstructive sleep apnea (OSA) syndrome is associated with cognitive and mood changes that include fatigue, sleepiness, memory difficulties, impaired executive function, irritability, and mood lability. In addition, autonomic disturbances include cardiovascular and ventilation changes. These authors evaluated whether these signs and symptoms are accompanied by structural brain changes. They used diffusion tensor imaging (DTI), a relatively new technique that allows calculation of fractional anisotropy (FA). FA reflects the number, coherence, and degree of myelination of nerve fibers. Study participants were 41 patients with moderate-to-severe OSA and 69 controls without sleep apnea.

Compared with controls, OSA patients had lower FA values in multiple brain areas, including areas within the caudal pons, left middle cerebellar peduncle, left corticospinal tract, deep cerebellar nuclei, ventral lateral thalamus, fornix, anterior cingulated gyrus, internal capsule, and parietal and frontal cortices. The authors speculate that the lower FA in these regions reflects demyelination, shrinkage of axons, axonal loss, and, possibly, small-vessel damage.