Sleep Apnea, Cognitive Profile, and Vascular Changes: An Intriguing Relationship

Background: Sleep breathing disorders can affect cognitive performances through complex brain anatomical and functional changes. Objective: Our aim was to evaluate the correlations between cognitive performances and obstructive sleep apnea syndrome (OSAS), as well as the possible influence of vascular factors. Methods: Thirty-four non-demented OSAS patients and 34 controls were submitted to a neuropsychological evaluation and to a vascular screening including the study of cerebrovascular reactivity by means of the breath-holding index (BHI) calculation. After 6 months, polisomnographic, neuropsychologic, and hemodynamics assessment was repeated in patients. Results: At baseline, some cognitive performances involved in executive and memory functions were significantly lower in patients with respect to controls. Significantly lower values in mean BHI were also detected in patients with respect to controls (p < 0.0001). At the 6-month evaluation, 18 patients had a reduction in OSAS severity (group 1) and 16 remained stable (group 2). Group 1 patients had a significant improvement in left and mean BHI (p < 0.001) and in short-term (p = 0.02) and long-term Rey Auditory Verbal Learning Test (p < 0.001). No change in cerebrovascular reactivity and cognitive profile was detected in group 2 patients. Conclusions: Patients with OSAS may experience a reduced cognitive efficiency. Improvement of OSAS was associated to favorable hemodynamic changes and increased level of performances in verbal memory tasks so suggesting an involvement of vascular underlying mechanisms in sustaining cognitive dysfunctions in OSAS. Our preliminary data suggest the need for further studies to deepen the knowledge about the relationships between OSAS, cerebral hemodynamic compromise, and cognitive impairment risk.