Cognitive function and treatment of obstructive sleep apnea syndrome

Among patients with obstructive sleep apnea syndrome (OSAS), impairment of cognitive function, i.e. deficits in memory, attention, and visuconstructiv e abilities are common. We applied different forms of treatment for patient s with newly diagnosed OSAS in a randomized study with a one-year follow-up . Patients with BMI > 40 kg/m(2) were excluded. After the initial diagnosti c work-up, male patients were considered to be candidates for either nasal continuous airway pressure (nCPAP) (27 patients) or surgical treatment (uvu lopalatopharyngoplasty with or without mandibular osteotomy) (23 patients). Within the groups, the patients were then randomized to active treatment ( nCPAP/surgery) or to conservative management. Cognitive function and severi ty of OSAS were assessed prior to treatment and 3 and 12 months later. At 1 2 months, all patients on nCPAP had a normal ODI4 index (<10), and were sig nificantly less somnolent than their controls; 3/11 of the surgically treat ed patients had a normal ODI4 index. Daytime somnolence was significantly l ess severe in the surgically treated patients than in their controls. Cogni tive function did not correlate importantly with daytime sleepiness or seve rity of OSAS; the best Pearson pairwise correlation coefficient was between ODI4 and the Bourdon-Wiersma (r=0.36). Success in treatment of OSAS did no t affect neuropsychological outcome. We concluded that the standard cogniti ve test battery is insufficiently sensitive to identify positive changes in patients with OSAS, especially among those with a high level of overall me ntal functioning.