Cognitive decline in metabolic syndrome is linked to microstructural white matter abnormalities

Subjects with metabolic syndrome (MetS) often show worse cognitive performance compared with the healthy population. We investigated whether microstructural white matter abnormalities are associated with cognitive performance in adults with MetS using diffusion tensor MR imaging. A total of 32 subjects with MetS (age 64.8 ± 7.8, 56.25 % female) and 23 age-, gender-, and education-matched healthy controls completed a battery of neuropsychological tests and diffusion tensor imaging (DTI) at 3-T MRI. Brain global and regional volumes, white matter fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (LD) were calculated. The least-square models adjusted for age, sex, HbA1c, hypertension, body mass index, hyperlipidemia, and white matter hyperintensities were used to evaluate the relationship between cognitive function and DTI. The MetS group had worse performance in verbal fluency (VF) and learning and memory function (total VF: T score (p = 0.01), VF: animals T score (p = 0.0001), Hopkins Verbal Learning Test (HVLT): Total recall T score (p = 0.0001), and HVLT: delayed recall T score (p = 0.002), as compared with controls. In the MetS group, abnormalities in diffusivity measures were associated with worse cognitive performance [VF: animals T score and left post-central gyrus-LD (p = 0.0007, r_adj 0.4), R angular gyrus-RD (p = 0.0008, r_adj 0.3), L supra-marginal gyrus-RD (p = 0.009, r_adj 0.2) after adjusting for age, sex, HbA1c, 24 h mean BP, presence of hyperlipidemia, and global white matter hyperintensities]. Microstructural white matter abnormalities in the MetS group might be the underlying mechanisms of worse verbal learning and memory performance.