Global and Regional Effects of Type 2 Diabetes Mellitus on Brain Tissue Volumes and Cerebral Vasoreactivity

OBJECTIVE: The aims of this study were to evaluate the regional effects of type 2 diabetes and associated conditions on cerebral tissue volumes and cerebral blood flow (CBF) regulation. RESEARCH DESIGN AND METHODS: CBF was examined in 26 diabetic (age 61.6 ± 6.6 years) and 25 control subjects (age 60.4 ± 8.6 years) using continuous arterial spin labeling (CASL) imaging during baseline, hyperventilation, and CO2 rebreathing. Regional gray (GM) and white matter (WM), cerebrospinal fluid (CSF), and white matter hyperintensities (WMHs) volumes were measured on T1-weighted inversion recovery fast gradient echo and fluid-attenuation inversion recovery MRI at 3 Tesla. RESULTS: The diabetic group had smaller global WM (p=0.006) and GM (p=0.001) and larger CSF (36.3%, p<0.0001) volumes than the control group. Regional differences were observed for WM (-13.1%, p=0.0008) and CSF (36.3%, p<0.0001) in the frontal region, for CSF (20.9%, p=0.0002) in the temporal region, and for GM (-3.0%, p=0.04) and CSF (17.6%, p=0.01) in the parieto-occipital region. Baseline regional CBF (p=0.006) and CO2 reactivity (p=0.005) were reduced in diabetic group. Hypoperfusion in the frontal region was associated with GM atrophy (p<0.0001). Higher hemoglobin A1C was associated with lower CBF (p<0.0001) and greater CSF (p=0.002) within temporal region. CONCLUSIONS: Type 2 diabetes is associated with cortical and subcortical atrophy involving several brain regions and with diminished regional cerebral perfusion and vasoreactivity. Uncontrolled diabetes may further contribute to hypoperfusion and atrophy. Diabetic metabolic disturbance and blood flow dysregulation that affects preferentially frontal and temporal regions may have implications for cognition and balance in elderly with diabetes. Abbreviations: CBF, cerebral blood flow● WM, white matter ● GM, gray matter ● CSF, cerebrospinal fluid, ● CASL, continuous arterial spin labeling ● WMHs, white matter hyperintensities