Objective Elderly patients with obstructive sleep apnea/hypopnea syndrome(OSAHS)has a higher risk of cardiovascular and cerebrovascular disease.However,changes of homocysteine(Hcy)as markers of cardiovascular and cerebrovascular disease associated with OSAHS and their mechanism have not been elucidated so far.This study aims to investigate the changes of both serum Hcy and oxidative stress and their possible links with OSAHS in elderly patients.Methods Based on polysomnogram(PSG)and age,83 patients with OSAHS were recruited and divided into elderly-OSAHS(n=32)and non-elderly OSAHS groups(n=51).Fifty two subjects without OSAHS were divided into elderly control(n=29)and non-elderly control groups(n=23).A total of 135 subjects were included in the present study.All subjects were recorded for PSG variables and the contents of homocysteine(Hcy),malonaldehyde(MDA),and glutathione(GSH)which were detected after sleep.Serum homocysteine was measured by cyclophorase.MDA and GSH were measured by spectrophotometer.Results(1)The serum levels of Hcy showed significant difference among the four groups(P<0.05).The concentrations of Hcy in elderly OSAHS patients were higher than in other groups,while those in the elderly control group were higher than in the non-elderly control the concentrations in the non-elderly OSAHS group were higher than in the non-elderly control.(2)The concentrations of MDA and GSH changed at an equal pace with Hcy in the four groups.(3)Multielement linearity regression analysis indicated a statistically significant relationship between Hcy concentration and age,MDA,GSH,and apnea hypopnea index(AHI).Conclusions(1)The concentrations of Hcy and oxidative stress have increased with advancing age.(2)The concentrations of Hcy and oxidative stress have further increased in the elderly patients with OSAHS.(3)Oxidative stress might cause high-level serum Hcy in the elderly patients with OSAHS. Objective Elderly patients with obstructive sleep apnea / hypopnea syndrome (OSAHS) has a higher risk of cardiovascular and cerebrovascular disease. Despite, changes of homocysteine ​​(Hcy) as markers of cardiovascular and cerebrovascular disease associated with OSAHS and their mechanism have not been elucidated so far . This study aims to investigate the changes of both serum Hcy and oxidative stress and their possible links with OSAHS in elderly patients. Methods Based on polysomnogram (PSG) and age, 83 patients with OSAHS were recruited and divided into elderly-OSAHS (n = 32) and non-elderly OSAHS groups (n = 51) .Fifty two subjects without OSAHS were divided into elderly control (n = 29) and non-elderly control groups (n = 23) .A total of 135 subjects were included in the present study. All subjects were recorded for PSG variables and the contents of homocysteine ​​(Hcy), malonaldehyde (MDA), and glutathione (GSH) which were detected after sleep.Serum homocysteine ​​was measured by cyclophorase. MDA and GSH were measured by Results: (1) The serum levels of Hcy showed significant difference among the four groups (P <0.05). The concentrations of Hcy in elderly OSAHS patients were higher than in other groups, while those in the elderly control group were higher than in the non-elderly control the concentrations in the non-elderly OSAHS group were higher than in the non-elderly control. (2) The concentrations of MDA and GSH changed at an equal pace with Hcy in the four groups. (3) Multielement linearity regression analysis indicated a statistically significant relationship between Hcy concentration and age, MDA, GSH, and apnea hypopnea index (AHI). Conclusions (1) The concentrations of Hcy and oxidative stress have increased with advancing age. (2) The concentrations of Hcy and oxidative stress have further increased in the elderly patients with OSAHS. (3) Oxidative stress might cause high-level serum Hcy in the elderly patients with OSAHS.