Basal Ganglia Mechanical Stiffness is Associated with Fluid Intelligence in Amnestic Mild Cognitive Impairment

Background Magnetic resonance elastography (MRE) is an MRI technique that uses mild, externally applied vibrations to quantify the mechanical properties of tissues in vivo. MRE measures, such as stiffness, have been shown to be sensitive to changes in brain health with aging and neurodegeneration. Here we used MRE to characterize differences in brain mechanical properties between individuals with amnestic mild cognitive impairment (aMCI) and cognitively unimpaired subjects (CU). Method A cohort of 67 cognitively unimpaired subjects (21M/46F; 60‐82y) and a cohort of 34 subjects with aMCI (11M/23F; 60‐89y) completed an MRE scan to assess their brain mechanical properties. From this, we quantified basal ganglia (BG) stiffness in each subject including the caudate, pallidum, putamen, and nucleus accumbens. Subjects also completed the NIH toolbox cognition battery from which we examined fluid cognition composite score, which reflects logic and reasoning skills. Result We found a significant group difference in stiffness of the basal ganglia (BG). Interestingly, aMCI subjects had significantly higher BG stiffness than CUs (2.99 vs. 2.89 kPa, p