Obstructive sleep apnea may increase the risk of Alzheimer's disease.

Objectives: Amyloid-β 1-40 (Aβ 1-40) and amyloid-β 1-42 (Aβ 1-42) are the proteins known to be involved in the pathogenesis of Alzheimer's disease (AD)-the most common cause of dementia in the elderly. Hypoxia is suspected to be one of conditions associated with Aβ plasma level increase. A common reason of hypoxia is obstructive sleep apnea (OSA), characterized by recurrent episodes of apnea.

Aim: The aim of the study was to evaluate plasma Aβ 1-40 and Aβ 1-42 concentrations in patients with OSA.

Methods: Patients with suspected OSA (n = 112) underwent polygraphic examinations Patients with confirmed OSA (n = 81) showed apnea/hypopnea index greater than or equal to 5. Mild and moderate form of the disease was defined when AHI was 5-30 (n = 38, OSA+), severe-when AHI was >30 (n = 43, OSA++). Individuals with AHI<5 (n = 31) served as control group (OSA-).

Results: Aβ 1-40 concentrations in OSA++ (191.1 pg/ml) group was significantly (p<0.05) higher compared with OSA- (76.9 pg/ml) and OSA+ (159.4 pg/ml) and correlated with selected parameters of hypoxemia severity. There were no differences in Aβ 1-42 concentration between the groups.

Conclusion: In patients with severe OSA Aβ 1-40 plasma concentrations are significantly higher compared with OSA- and OSA+ and seem to be related to hypoxia severity, which may indicate increased risk of AD development in this group of patients.