Is Anything the Matter with White Matter in Insulin-Resistant Patients?

Jonathan Silver, MD

Brain microstructures may be abnormal even in individuals without cognitive symptoms.

Higher fasting glucose and glycosylated hemoglobin levels, even within the normal range, are associated with cognitive problems and hippocampal abnormalities (NEJM JW Psychiatry May 6 2013 and Nov 1 2013). Extending these findings, researchers have examined white-matter integrity on diffusion tensor imaging in 127 cognitively healthy individuals (age range, 41–86) who were divided into high and low insulin-resistance levels on the homeostasis model of assessment of insulin resistance (HOMA-IR), which is calculated from fasting levels of serum insulin and glucose.

Patients with high HOMA-IR had higher triglyceride concentrations, higher glycosylated hemoglobin levels, and greater use of hypoglycemic medications. Independent of confounding factors, patients with high HOMA-IR had widespread lower values on two measures, fractional anisotropy and axial diffusivity, indicating microstructural irregularities. Across all subjects, diffusion measures were linearly associated with HOMA-IR levels.

Citation(s):

Ryu SY et al. Effects of insulin resistance on white matter microstructure in middle-aged and older adults. Neurology 2014 Apr 25; [e-pub ahead of print].