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.