Effects of ABCA1 R219K Polymorphism and Serum Lipid Profiles on Mild Cognitive Impairment in Type 2 Diabetes Mellitus

Background: Accumulated evidence suggests that adverse lipid changes are risk factors for type 2 diabetes mellitus (T2DM) and neurodegenerative disorders. The ATP-binding cassette A1 transporter (ABCA1) gene contributes to both lipid processing and amyloid-β formation and thus shows promise as a biological target in the pathology of mild cognitive impairment (MCI) in T2DM. Objective: This study aimed to investigate the interactions among lipids, ABCA1 R219K polymorphism, and cognitive function in T2DM. Methods: Clinical parameters, including lipids, were measured. The testing scores of different cognitive domains were recorded, and the ABCA1 R219K polymorphisms were analyzed. Results: A total of 226 patients, including 124 MCI patients and 102 controls, were enrolled in this study. T2DM patients with MCI showed lower cognitive functions, serum high-density lipoprotein (HDL-c), and apolipoprotein A1 (apoA-I) levels; and higher total cholesterol level than the controls. Serum HDL-c (P=0.001) and apoA-I (P=0.016) were positively associated with the MoCA score. Further stratification analyses revealed that the subjects with higher HDL-c concentration showed better attention and memory for verbal, visual, and logical functions than the group with lower HDL-c concentration (P<0.05). No significant differences were observed among the distributions of ABCA1 R219K variants between MCI patients and controls; however, the KK genotype carriers presented higher apoA-I levels than those with RR genotype in MCI individuals. Conclusion: This study does not support the association between R219K polymorphism and T2DM-related MCI. However, our data suggested that the serum HDL-c level might positively influence cognition, especially memory function, in T2DM patients. Further studies are needed to determine the interaction between lipids and ABCA1 genotype and its effect on cognition in T2DM patients.