Patients with obstructive sleep apnea (OSA) often complain of cognitive difficulties, which can improve after beginning continuous positive airway pressure (CPAP) therapy. CPAP therapy may reverse the structural neural injury that occurs if patients are compliant with treatment, according to research published in SLEEP.

OSA is a common disorder characterized by repeated episodes of upper airway closure that occurs during sleep. It is theorized that hypoxemia, as opposed to sleep fragmentation, may cause mild cognitive impairment and dementia in patients diagnosed with OSA. The hypoxemia may cause an increase in sympathetic vasoconstriction, which in turn changes the structure and function of blood vessels.

Conventional neuroimaging studies have been inconclusive, but voxel-based morphometry has shown alterations in brain matter. Areas of brain matter affected during apnea included the hippocampus, left parietal cortex, and superior frontal gyrus.

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CPAP therapy resulted in an increase in gray matter in the hippocampus and frontal regions with improvement in short term memory, reported Vincenza Castronovo, PhD, of the Scientific Institute and University Ospedale San Raffaele in Milan, Italy, and colleagues.

The team of researchers studied 17 patients with OSA and 15 controls. The pre-treated sleep apnea patients showed impairment in most cognitive areas. Participants with OSA had an apnea–hypopnea (AHI) of greater than 30 (severe OSA) whereas their age and education -matched controls had an AHI of less than five (normal).

Over the course of 12 months of therapy, CPAP-compliant patients with OSA demonstrated a near complete reversal in cognitive decline.

This is yet another reason why patients with OSA should be treated. During screening, I ask my patients if they are experiencing cognitive difficulties and most answer that they do. Most of these patients also note significant improvement in their cognitive difficulties after treatment.

I’m excited to share the first evidence that CPAP therapy can improve my patients’ cognitive problems, and I hope you share this encouraging news with your patients as well.

Sharon M. O’Brien, MPAS, PA-C, is a practicing clinician with an interest in helping patients understand the importance of sleep hygiene and the impact of sleep on health.


  1. Castronovo V et al. SLEEP. 2014; doi: