Background: Pima Indians from the Gila River Indian Community in Arizona, USA, have a high prevalence of type 2 diabetes and have been studied for decades to evaluate the risk factors for and trajectory of diabetic complications. Here, we aimed to identify metabolic factors associated with central nervous system sequelae in this population.

Methods: Cognitive performance and ultrastructural brain volumes were determined in Pima Indians via the NIH Toolbox Cognitive Battery (NIHTB-CB) (n=51) and MRI studies (n=40). The NIHTB-CB Composite Score was the primary measure of cognitive function, adjusting for age, sex, race, and education level. MRI derived morphology measures included total cortical volume and white and gray matter volumes. Metabolic factors included duration of diabetes, height, weight, BMI, SBP, DBP, HbA1c, triglycerides, HDL, LDL, and total cholesterol. We performed univariate linear regressions on MRI outcomes and NIHTB-CB Composite Scores as functions of metabolic factors after adjusting for age/sex, and we calculated Pearson’s correlation between each MRI morphology outcome and the Composite Score.

Results: Of the 51 subjects who underwent the NIHTB-CB, 40 completed an MRI. Linear regression models revealed that only BMI associated with both total cortical volume (BMI point estimate (PE): -.0007, CI: -.001, -.0002) and total gray matter volume (BMI PE:-.0009, CI: -.001, -.0003). No metabolic factors associated with the NIHTB-CB Composite Score, and the NIHTB-CB Composite Score did not correlate with any morphology measures.

Conclusion: Increased BMI was associated with both decreased cortical volume and gray matter volume in this Pima cohort, similar to observations found for obesity in previously published cohorts. Though volume measures and NIHTB-CB scores did not correlate in this study, future work will analyze additional MRI based morphology measures to evaluate correlations with individual NIHTB-CB tests and assess changes over time.


R.E. Henn: None. E.L. Reynolds: None. A. Patterson: None. R.G. Nelson: None. E.L. Feldman: Consultant; Self; Novartis Pharmaceuticals Corporation. B.C. Callaghan: None.


National Institutes of Health (R24DK082841, T32NS0007222); Robert and Katherine Jacobs Environmental Health Initiative; Robert E. Nederlander, Sr. Program for Alzheimer’s Research; National Institute of Diabetes and Digestive and Kidney Diseases; Sinai Medical Staff Foundation

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