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Abstract
Objective: To investigate the potential relationship between insulin resistance (IR) and white matter (WM) microstructure using diffusion tensor imaging in cognitively healthy middle-aged and older adults.
Methods: Diffusion tensor imaging was acquired from 127 individuals (age range 41–86 years). IR was evaluated by the homeostasis model assessment of IR (HOMA-IR). Participants were divided into 2 groups based on HOMA-IR values: “high HOMA-IR” (≥2.5, n = 27) and “low HOMA-IR” (<2.5, n = 100). Cross-sectional voxel-based comparisons were performed using Tract-Based Spatial Statistics and anatomically defined regions of interest analysis.
Results: The high HOMA-IR group demonstrated decreased axial diffusivity broadly throughout the cerebral WM in areas such as the corpus callosum, corona radiata, cerebral peduncle, posterior thalamic radiation, and right superior longitudinal fasciculus, and WM underlying the frontal, parietal, and temporal lobes, as well as decreased fractional anisotropy in the body and genu of corpus callosum and parts of the superior and anterior corona radiata, compared with the low HOMA-IR group, independent of age, WM signal abnormality volume, and antihypertensive medication status. These regions additionally demonstrated linear associations between diffusion measures and HOMA-IR across all subjects, with higher HOMA-IR values being correlated with lower axial diffusivity.
Conclusions: In generally healthy adults, greater IR is associated with alterations in WM tissue integrity. These cross-sectional findings suggest that IR contributes to WM microstructural alterations in middle-aged and older adults.
GLOSSARY
- AD=
- Alzheimer disease;
- CC=
- corpus callosum;
- DA=
- axial diffusivity;
- DR=
- radial diffusivity;
- DTI=
- diffusion tensor imaging;
- FA=
- fractional anisotropy;
- HOMA-IR=
- homeostasis model assessment of insulin resistance;
- IR=
- insulin resistance;
- PLIC=
- posterior limb of internal capsule;
- ROI=
- region of interest;
- TBSS=
- Tract-Based Spatial Statistics;
- T2DM=
- type 2 diabetes mellitus;
- WM=
- white matter;
- WMSA=
- white matter signal abnormality
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received October 29, 2013.
- Accepted in final form February 24, 2014.
- © 2014 American Academy of Neurology
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