title: Biomarkers for Early Diagnostic of Mild Cognitive Impairment in Type-2 Diabetes Patients: A Multicentre, Retrospective, Nested Case-Control Study.
abstract: BACKGROUND
  Both type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) are common age-associated disorders and T2DM patients show an increased risk to suffer from AD, however, there is currently no marker to identify who in T2DM populations will develop AD. Since glycogen synthase kinase-3β (GSK-3β) activity, ApoE genotypes and olfactory function are involved in both T2DM and AD pathogenesis, we investigate whether alterations of these factors can identify cognitive impairment in T2DM patients.
  
  
  METHODS
  The cognitive ability was evaluated using Minimum Mental State Examination (MMSE) and Clinical Dementia Rating (CDR), and the mild cognitive impairment (MCI) was diagnosed by Petersen's criteria. GSK-3β activity in platelet, ApoE genotypes in leucocytes and the olfactory function were detected by Western/dot blotting, the amplification refractory mutation system (ARMS) PCR and the Connecticut Chemosensory Clinical Research Center (CCCRC) test, respectively. The odds ratio (OR) and 95% confidence intervals (95% CI) of the biomarkers for MCI diagnosis were calculated by logistic regression. The diagnostic capability of the biomarkers was evaluated by receiver operating characteristics (ROC) analyses.
  
  
  RESULTS
  We recruited 694 T2DM patients from Jan. 2012 to May. 2015 in 5 hospitals (Wuhan), and 646 of them met the inclusion criteria and were included in this study. 345 patients in 2 hospitals were assigned to the training set, and 301 patients in another 3 hospitals assigned to the validation set. Patients in each set were randomly divided into two groups: T2DM without MCI (termed T2DM-nMCI) or with MCI (termed T2DM-MCI). There were no significant differences for sex, T2DM years, hypertension, hyperlipidemia, coronary disease, complications, insulin treatment, HbA1c, ApoE ε2, ApoE ε3, tGSK3β and pS9GSK3β between the two groups. Compared with the T2DM-nMCI group, T2DM-MCI group showed lower MMSE score with older age, ApoE ε4 allele, higher olfactory score and higher rGSK-3β (ratio of total GSK-3β to Ser9-phosphorylated GSK-3β) in the training set and the validation set. The OR values of age, ApoE ε4 gene, olfactory score and rGSK-3β were 1.09, 2.09, 1.51, 10.08 in the training set, and 1.06, 2.67, 1.47, 7.19 in the validation set, respectively. The diagnostic accuracy of age, ApoE ε4 gene, olfactory score and rGSK-3β were 0.76, 0.72, 0.66, 0.79 in the training set, and 0.70, 0.68, 0.73, 0.79 in the validation set, respectively. These four combined biomarkers had the area under the curve (AUC) of 82% and 86%, diagnostic accuracy of 83% and 81% in the training set and the validation set, respectively.
  
  
  CONCLUSIONS
  Aging, activation of peripheral circulating GSK-3β, expression of ApoE ε4 and increase of olfactory score are diagnostic for the mild cognitive impairment in T2DM patients, and combination of these biomarkers can improve the diagnostic accuracy.
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Department of Neurology, Wuhan General Hospital of Guangzhou Command, Wuhan 430070, China.
authors.forename: Zhi-Peng
authors.initials: ZP
authors.lastname: Xu
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Su-Lian
authors.initials: SL
authors.lastname: Yang
authors.affiliation: Department of Endocrinology, The Central Hospital of Wuhan, Wuhan 430014, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Zhao
authors.affiliation: Department of Endocrinology, Wuhan Hospital of Traditional Chinese Medicine, Wuhan 430014, China.
authors.forename: Cheng-Hong
authors.initials: CH
authors.lastname: Zheng
authors.affiliation: Department of Neurology, Wuhan General Hospital of Guangzhou Command, Wuhan 430070, China.
authors.forename: Hong-Hua
authors.initials: HH
authors.lastname: Li
authors.affiliation: Li-Yuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430077, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Rong-Xi
authors.initials: RX
authors.lastname: Huang
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Meng-Zhu
authors.initials: MZ
authors.lastname: Li
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Shu-Juan
authors.initials: SJ
authors.lastname: Zhang
authors.affiliation: Department of Neurology, The Central Hospital of Wuhan, Wuhan 430014, China.
authors.forename: Pei-Yan
authors.initials: PY
authors.lastname: Zhan
authors.affiliation: Department of Endocrinology, Wuhan Hospital of Traditional Chinese Medicine, Wuhan 430014, China.
authors.forename: Li-Fang
authors.initials: LF
authors.lastname: Zhang
authors.affiliation: Department of Endocrinology, The Central Hospital of Wuhan, Wuhan 430014, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Deng
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Yan-Chao
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Jing-Wang
authors.initials: JW
authors.lastname: Ye
authors.affiliation: Department of Endocrinology, Wuhan General Hospital of Guangzhou Command, Wuhan 430070, China.
authors.forename: Hu-Jun
authors.initials: HJ
authors.lastname: Ren
authors.affiliation: Department of Endocrinology, The Central Hospital of Wuhan, Wuhan 430014, China.
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.affiliation: Department of Endocrinology, The First Hospital of Wuhan, Wuhan 430022, China.
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Kong
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Fang
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Qiu-Zhi
authors.initials: QZ
authors.lastname: Zhou
authors.affiliation: School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Jiang
authors.affiliation: Health Service Center of Jianghan District, Wuhan 430014, China.
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Li
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong 226000, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong 226000, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Ke
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong 226000, China.
authors.forename: Gong-Ping
authors.initials: GP
authors.lastname: Liu
authors.affiliation: Department of Pathophysiology, School of Basic Medicine and the Collaborative Innovation Center for Brain Science, Key Laboratory of Ministry of Education of China for Neurological Disorders, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong 226000, China.
authors.forename: Jian-Zhi
authors.initials: JZ
authors.lastname: Wang
mesh_terms: D000368:Aged; D000483:Alleles; D000544:Alzheimer Disease / Q000097:blood* / Q000209:etiology / Q000473:pathology; D053327:Apolipoprotein E4 / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000378:metabolism; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000097:blood* / Q000209:etiology / Q000473:pathology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000473:pathology; D005260:Female; D005838:Genotype; D000071679:Glycogen Synthase Kinase 3 beta / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D053327:Apolipoprotein E4; D015415:Biomarkers; D000071679:Glycogen Synthase Kinase 3 beta
keywords: AD, Alzheimer's disease; ARMS, amplification refractory mutation system; AUC, the area under the curve; Alzheimer's disease; ApoE gene; ApoE, apolipoprotein E; CCCRC, Connecticut Chemosensory Clinical Research Center; CDR, clinical dementia rating; CI, confidence intervals; GSK-3β, glycogen synthase kinase-3β; Glycogen synthase kinase-3β; HbA1c, hemoglobin A1c; MCI, mild cognitive impairment; MMSE, minimum mental state examination; Mild cognitive impairment; OR, odds ratio; Olfactory score; ROC, receiver operating characteristics; T2DM, type 2 diabetes mellitus; Type 2 diabetes mellitus