OBJECTIVE: To explore the correlation between diabetic nephropathy (DN) and cognitive impairment through examining the cognitive function and the metabolism of the cerebrum in Type 2 diabetes mellitus patients at different stages of renal function.
 METHODS: Eighty six patients with Type 2 diabetes mellitus (T2DM) were enrolled for this study. According to the urinary albumin excretion rate (UAER), the patients were divided into a T2DM without DN group (DM group, n=33), an early DN group (DN-III group, n=26) and a clinical stage group (DN-IV group, n=27). Thirty healthy adults were selected as a control group (NC group). Biochemical indexes and UAER were measured, and glomerular filtration rate (GFR) was detected by single-photon emission computed tomography (SPECT). The cognitive function was measured by Montreal Cognitive Assessment (MoCA, Beijing version) and mini-mental state examination (MMSE). The peak areas of N-acetylasparte (NAA), creatine (Cr), choline-containing compounds (Cho) were detected by proton magnetic resonance spectroscopy (1H-MRS).
 RESULTS: 1) There was no statistical difference in MMSE scores between the DM group and the control group. The scores of MoCA in the DN-III group or in the DN-IV group were significant less than that in the NC group (F=3.66, P<0.05); 2) There was significant difference in left N-acetylaspartate (LNAA), left choline (LCho) among the diabetes groups. Compared with the DM group, the level of LNAA was decreased significantly (t=3.826, P<0.05) while the LCho was increased significantly (t=4.373, P<0.05) in the DN groups, with statistic difference between the 2 groups (t=3.693, P<0.05); 3) The MoCA scores of T2DM patients were negatively correlated with UAER (r=-0.285, P<0.05), while positively correlated with GFR (r=0.379, P<0.05); 4) Logistic regression analysis indicated that UAER and GFR were the major risky factors for diabetic cognitive impairment.
 CONCLUSION Diabetic cognitive impairment is closely correlated with the nephropathy in patients with Type 2 diabetes. With the decline in glomerular filtration function, the cognitive disorder tends to be aggravated. The hippocampal brain metabolism may have some changes in left side of Cho/Cr in patients with diabetic nephropathy.
Adult ; Aspartic Acid ; analogs & derivatives ; metabolism ; Case-Control Studies ; Cerebrum ; metabolism ; Choline ; metabolism ; Cognition ; Cognition Disorders ; epidemiology ; Creatine ; metabolism ; Diabetes Mellitus, Type 2 ; physiopathology ; Diabetic Nephropathies ; epidemiology ; Glomerular Filtration Rate ; Humans ; Neuropsychological Tests

Abstract: To investigate the changes of cerebral blood flow(CBF) in patients with type 2 diabetes mellitus(T2 DM) and its correlation with cognitive function and olfactory impairment. Methods: Cognitive function assessment and smell identification test were performed on 83 patients with T2 DM and 62 healthy controls(HC). Three-dimensional pseudo-continuous arterial spin labeling(3 D-pcASL) head images were collected from the two groups. CBF values of the cerebral cortex were compared between the patients and HC after the postprocessing. Correlations between the CBF values and cognitive function assessment and between the CBF values and smell identification test scores were analyzed as well. Results: Compared to the HC, Chinese smell identification test(CSIT), montreal cognitive assessment(MoCA), digit span test(DST), verbal fluency test(VFT) scores were lower in T2 DM patients(P<0.05).The CBF of the bilateral middle frontal gyrus in T2 DM patients was higher than that in HC group(P<0.001). The CBF of the bilateral gyrus rectus and olfactory cortex in T2 DM patients was lower than that in HC group(P<0.001). Conclusion The cognitive and olfactory function of patients with T2 DM decreased. Patients with T2 DM have abnormal perfusion in the bilateral middle frontal gyrus, gyrus rectus and olfactory cortex, revealing that CBF changes in these brain regions may be one of the causes for cognitive impairment and olfactory dysfunction in T2 DM.