White matter damage caused by severe obstructive sleep apnea can be reversed by continuous positive airway pressure (CPAP) therapy, according to results of a neuroimaging study published in the September issue of Sleep.
Participants with severe, untreated sleep apnea had a significant reduction in white matter fiber integrity in multiple brain areas. This brain damage was accompanied by impairments to cognition, mood, and daytime alertness. Although three months of CPAP therapy produced only limited improvements to damaged brain structures, 12 months of CPAP therapy led to an almost complete reversal of white matter abnormalities. Treatment also produced significant improvements in nearly all cognitive tests, mood, alertness, and quality of life.
“Structural neural injury of the brain of obstructive sleep apnea patients is reversible with effective treatment,” said principal investigator and lead author Vincenza Castronovo, PhD, clinical psychologist at the Sleep Disorders Center at San Raffaele Hospital and Vita-Salute San Raffaele University in Milan. “Treatment with CPAP, if patients are adherent to therapy, is effective for normalizing the brain structure.”
The study involved 17 men with severe, untreated obstructive sleep apnea who had an average age of 43. They were evaluated at baseline and after three and 12 months of treatment with CPAP therapy. At each time, they underwent a neuropsychologic evaluation and a diffusion tensor imaging examination. DTI is a form of magnetic resonance imaging that measures the flow of water through brain tissue. Participants were compared with 15 age-matched, healthy controls who were evaluated only at baseline.
A previous study by Dr. Castronovo’s group found similar damage to gray matter volume in multiple brain regions of people with severe sleep apnea. Improvements in gray matter volume appeared after three months of CPAP therapy. According to the authors, the two studies suggest that the white matter of the brain takes longer to respond to treatment than the gray matter.
“We are seeing a consistent message that the brain can improve with treatment,” said co-principal investigator Mark Aloia, PhD, Associate Professor of Medicine at National Jewish Health in Denver, and Senior Director of Global Clinical Research for Philips Respironics in Thornton, Colorado. “We know that PAP therapy keeps people breathing at night, but demonstrating effects on secondary outcomes is critical, and brain function and structure are strong secondary outcomes.”