Effects of CPAP treatment on psychological status in patients with severe obstructive sleep apnoea

The aim of this study was to evaluate the effects of nocturnal continuous positive airway pressure (CPAP) breathing on the emotional status and cognitive function in 20 patients with severe obstructive sleep apnoea (OSA) (mean +/- SD apnoea/hypopnoea index = 67 +/- 16, mean overnight arterial oxygen saturation = 83 +/- 10%). Psychological tests were performed before, after three, and after twelve months of CPAP treatment. At initial investigation, amongst cognitive functions, the most disturbed were concentration and recent memory. The majority of subjects demonstrated increased mental stress, depression, and anxiety. Anxiety correlated with AHI (r = 0.68). Mental stress correlated with AHI (r = 0.56) and deficiency of Stage 2 NREM sleep (r = -0.55). CPAP treatment resulted in significant improvement in cognitive function; concentration, recent verbal, visual and spatial memory were already seen at three months. No improvement in IQ and in emotional status after three months and one year of treatment was found. It is concluded that in patients with severe OSA CPAP treatment results in a significant early improvement in cognitive function but not in emotional status.