Combined effects of type 2 diabetes and hypertension associated with cortical thinning and impaired cerebrovascular reactivity relative to hypertension alone in older adults

• Published in: NeuroImage clinical Vol. 5; no. C; pp. 36 - 41
• Main Authors: Tchistiakova, Ekaterina, Anderson, Nicole D, Greenwood, Carol E, MacIntosh, Bradley J
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier 01.01.2014
• Subjects: Aged; Atrophy - pathology; Atrophy - physiopathology; Breath Holding; Cerebral Cortex - pathology; Cerebral Cortex - physiopathology; Cerebrovascular Circulation - physiology; Cerebrovascular reactivity; Cortical thickness; Diabetes; Diabetes Mellitus, Type 2 - complications; Diabetes Mellitus, Type 2 - pathology; Diabetes Mellitus, Type 2 - physiopathology; Female; Humans; Hypertension; Hypertension - complications; Hypertension - pathology; Hypertension - physiopathology; Magnetic Resonance Imaging; Male; Organ Size - physiology; CThk, cortical thickness; Hypertension; Cortical thickness; WMH, white matter hyperintensities; HTN, hypertension; T2DM, type 2 diabetes mellitus; FLEX, fuzzy lesion extractor; 3DMPRAGE, three-dimensional magnetization-prepared rapid gradient-echo; HBA1C, hemoglobin A1C; CVR, cerebrovascular reactivity; Cerebrovascular reactivity; TICS, Telephone Interview for Cognitive Status; FLAIR, fluid attenuation inversion recovery; BH, breath hold; Diabetes; BOLD, blood oxygenation level dependent imaging
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2014.05.020

Type 2 diabetes mellitus is characterized by metabolic dysregulation in the form of hyperglycemia and insulin resistance and can have a profound impact on brain structure and vasculature. The primary aim of this study was to identify brain regions where the combined effects of type 2 diabetes and hypertension on brain health exceed those of hypertension alone. A secondary objective was to test whether vascular impairment and structural brain measures in this population are associated with cognitive function. We enrolled 18 diabetic participants with hypertension (HTN + T2DM, 7 women, 71.8 ± 5.6 years) and 22 participants with hypertension only (HTN, 12 women, 73.4 ± 6.2 years). Cerebrovascular reactivity (CVR) was assessed using blood oxygenation level dependent (BOLD) MRI during successive breath holds. Gray matter structure was evaluated using cortical thickness (CThk) measures estimated from T1-weighted images. Analyses of cognitive and blood data were also performed. Compared to HTN, HTN + T2DM had decreased CVR and CThk in a spatially overlapping region of the right occipital lobe (P < 0.025); CVR group differences were more expansive and included bilateral occipito-parietal areas (P < 0.025). Whereas CVR showed no significant associations with measures of cognitive function (P > 0.05), CThk in the right lingual gyrus ROI and regions resulting from a vertex-wise analysis (including posterior cingulate, precuneus, superior and middle frontal, and middle and inferior temporal regions (P < 0.025) were associated with executive function. Individuals with T2DM and HTN showed decreased CVR and CThk compared to age-matched HTN controls. This study identifies brain regions that are impacted by the combined effects of comorbid T2DM and HTN conditions, with new evidence that the corresponding cortical thinning may contribute to cognitive decline.