Jie Zhang1, Yiping Yang2, Xiaobo Yang3, Jian Qin3, Xiao Wei3, Yang Peng3, Zhiying Li1, Li'e Zhang3, Zhiyong Zhang4, Yunfeng Zou5. 1. Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, 530021, Guangxi, China. 2. Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, 530021, Guangxi, China; Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, Guangxi, China. 3. Department of Occupational Health and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, 530021, Guangxi, China. 4. Department of Environmental Health and Occupational Medicine, School of Public Health, Guilin Medical University, Guilin, 541100, Guangxi, China. Electronic address: rpazz@163.com. 5. Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, 530021, Guangxi, China; Guangxi Colleges and Universities Key Laboratory of Prevention and Control of Highly Prevalent Diseases, Guangxi Medical University, Nanning, 530021, Guangxi, China. Electronic address: zouyunfeng@gxmu.edu.cn.
Abstract
BACKGROUND: Elevated manganese (Mn) exposure impairs cognition in adults and children, but the association between Mn and cognitive function in elderly people is unclear. Previous studies have linked Mn neurotoxicity in AD to Aβ-dependent mechanisms. However, the association between Mn and plasma APP and Aβ in the general elderly population remains unknown. This study aimed to investigate the association between Mn exposure and cognitive function, plasma APP and plasma Aβ in older adults. METHODS: Cognitive abilities in 375 men aged 60 and older in Guangxi, China were assessed using the Mini-Mental State Examination (MMSE) and cognitive impairment were identified using education-stratified cut-off points of MMSE scores. Urinary Mn levels and plasma APP, and Aβ levels were measured using ICP-MS and ELISA, respectively. RESULTS: A total of 109 (29.07 %) older men were identified as having cognitive impairment. The median urinary Mn level was 0.22 μg/g creatinine. Urinary Mn levels were negatively correlated with MMSE scores (β = -1.35, 95 % CI: -2.65 to -0.06; p = 0.041). In addition, higher concentrations of urinary manganese were associated with a greater risk of cognitive impairment (OR = 2.03, 95 % CI: 1.14-3.59; comparing the highest and lowest manganese; p = 0.025). Moreover, plasma APP levels were inversely associated with urinary Mn levels (r = -0.123, p = 0.020), and positively associated with MMSE scores (r = 0.158, p = 0.002). Surprisingly, no correlations were observed between plasma Aβ42, Aβ40, Aβ40/Aβ42, or Aβ42/Aβ40 and urinary Mn levels and MMSE scores. CONCLUSION: These results suggested that Mn exposure is negatively associated with older men's cognition and plasma APP levels, but not plasma Aβ levels.
BACKGROUND: Elevated manganese (Mn) exposure impairs cognition in adults and children, but the association between Mn and cognitive function in elderly people is unclear. Previous studies have linked Mn neurotoxicity in AD to Aβ-dependent mechanisms. However, the association between Mn and plasma APP and Aβ in the general elderly population remains unknown. This study aimed to investigate the association between Mn exposure and cognitive function, plasma APP and plasma Aβ in older adults. METHODS: Cognitive abilities in 375 men aged 60 and older in Guangxi, China were assessed using the Mini-Mental State Examination (MMSE) and cognitive impairment were identified using education-stratified cut-off points of MMSE scores. Urinary Mn levels and plasma APP, and Aβ levels were measured using ICP-MS and ELISA, respectively. RESULTS: A total of 109 (29.07 %) older men were identified as having cognitive impairment. The median urinary Mn level was 0.22 μg/g creatinine. Urinary Mn levels were negatively correlated with MMSE scores (β = -1.35, 95 % CI: -2.65 to -0.06; p = 0.041). In addition, higher concentrations of urinary manganese were associated with a greater risk of cognitive impairment (OR = 2.03, 95 % CI: 1.14-3.59; comparing the highest and lowest manganese; p = 0.025). Moreover, plasma APP levels were inversely associated with urinary Mn levels (r = -0.123, p = 0.020), and positively associated with MMSE scores (r = 0.158, p = 0.002). Surprisingly, no correlations were observed between plasma Aβ42, Aβ40, Aβ40/Aβ42, or Aβ42/Aβ40 and urinary Mn levels and MMSE scores. CONCLUSION: These results suggested that Mn exposure is negatively associated with older men's cognition and plasma APP levels, but not plasma Aβ levels.