The Role of Type 2 Diabetes and Metformin Use in Cognitive Decline
Chilson, Kelley R.
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Objectives: Primary objectives of the present study include exploring the role of both A1C values and the anti-diabetic medication, metformin, on cognitive decline through measured by a brief neuropsychological exam (BNE) and the Montreal Cognitive Assessment (MoCA). Method: Eleven years of archival cognitive testing and medical information from a total of 479 East Central Florida Memory Disorder Clinic patients (52.8 % female, 88.5% Caucasian, Mage = 78.79 years) was utilized for the present study. Participants were placed into two groups: Type 2 diabetes (n = 239) and a control group (n = 240). Cognitive testing data were collected via MoCA screening tests and BNE’s that assessed six cognitive domains: language, attention, executive functioning, motor and processing speed, visuospatial skills, and learning and memory. Patients diagnosed with Type 2 diabetes were identified from patient electronic medical records (EMR) searched via Health First Information Technology (IT). Results: There was no significant difference in total BNE scores between the Type 2 diabetes group (M = 12.22, SD = 3.83) and the control group (M = 11.80, SD = 3.98; t (477) = 1.17, p = .24, two-tailed). However, a slight difference in domain scores was detected between groups as revealed by a one-way between-groups multivariate analysis of variance (MANOVA), Wilks’ λ = .97; F (6, 468) = 2.45, p = .024; partial eta squared = .03, with a significant difference for visuospatial domain, F (1, 473) = 5.49, p = .02, partial eta squared = .01. With regard to metformin use, a significant difference in the learning and memory domain scores for participants on metformin (M = 1.90, SD = .81) compared to participants on other medication classes (M = 1.69, SD = .77; t (237) = -1.95, p = .05 was found, suggesting participants taking metformin demonstrated slightly better performance on learning and memory measures. Lastly, a significant difference in MoCA scores between participants taking the drug metformin (M = 20.26, SD = 4.19) compared to participants taking drugs from other classes of anti-diabetes medications (M = 18.67, SD = 5.05; t (229) = -2.31, p = .02), suggesting participants taking metformin performed significantly better on this measure compared to participants taking other anti-diabetes medications. Conclusions: On cognitive measures of the BNE, participants demonstrated a higher level of homogeneity than hypothesized, with only slight differences in cognitive domain scores. The most important findings of the present study were the differences in cognitive performance between participants taking metformin versus other anti-diabetic medications. Results support previous literature suggesting a neuroprotective effect of metformin, as opposed to newer studies that suggest a cognitive-impairing role of metformin.