title: Relationship between blood levels of methyl donor and folate and mild cognitive impairment in Chinese patients with type 2 diabetes: a case-control study.
abstract: Type 2 diabetes is a risk factor for Alzheimer's disease and mild cognitive impairment. Folate insufficiency fosters a decline in the sole methyl donor, S-adenosylmethionine, and decreases methylation potential, which is associated with Alzheimer's disease in non-diabetic patients. However, little is known in diabetic patients. We analyzed plasma levels of S-adenosylmethionine, S-adenosylhomocysteine and serum level of folate in 100 elderly type 2 diabetic patients with and without mild cognitive impairment. S-adenosylmethionine/S-adenosylhomocysteine ratio was used to reflect the methylation potential. Patients with mild cognitive impairment had significantly lower levels of S-adenosylmethionine, folate and S-adenosylmethionine/S-adenosylhomocysteineratios. Furthermore, logistic regression analysis indicated the plasma S-adenosylmethionine, S-adenosylmethionine/S-adenosylhomocysteine ratio and serum folate (OR, 0.96, 0.698, 0.72, respectively; p<0.05) were negatively associated with risk of mild cognitive impairment, even after adjusting for related covariates. In addition, folate level was positively correlated with S-adenosylmethionine and the S-adenosylmethionine/S-adenosylhomocysteine ratio (r = 0.38, 0.46, respectively; p<0.05) among patients within the middle tertile of folate levels (6.3-9.1 µg/L). These findings indicate mild cognitive impairment is associated with lower levels of S-adenosylmethionine, folate and weakened methylation potential; plasma S-adenosylmethionine and methylation potential may be predicted by serum folate within a suitable range of folate concentrations in diabetic patients.
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China ; Department of Endocrinology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, The Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Miaoyan
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Meilin
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, The Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Juhong
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Shijing
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Shanchun
authors.initials: S
authors.lastname: Qin
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Cardiology, General Hospital of Tianjin Medical University, Tianjin 300052, China.
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai, Road, Heping District, Tianjin 300070, China.
authors.forename: Guowei
authors.initials: G
authors.lastname: Huang
keywords: folate; methyl donor; mild cognitive impairment; type 2 diabetes