title: Combined effects of type 2 diabetes and hypertension associated with cortical thinning and impaired cerebrovascular reactivity relative to hypertension alone in older adults.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto, ON M5G 2M9, Canada ; Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, 2075 Bayview Ave., Toronto, ON M4N 3M5, Canada ; Brain Sciences Research Program, Sunnybrook Research Institute, 2075 Bayview Ave., Toronto, ON M4N 3M5, Canada.
authors: Ekaterina
authors: E
authors: Tchistiakova
authors: Department of Psychology, University of Toronto, 100 St. George Street, Toronto, ON M5S 1A8, Canada ; Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, ON M6A 2E1, Canada ; Department of Medicine (Psychiatry), University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
authors: Nicole D
authors: ND
authors: Anderson
authors: Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, ON M6A 2E1, Canada ; Department of Nutritional Sciences, University of Toronto, FitzGerald Building, 150 College Street, Toronto, ON M5S 3E2, Canada.
authors: Carol E
authors: CE
authors: Greenwood
authors: Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto, ON M5G 2M9, Canada ; Heart and Stroke Foundation Canadian Partnership for Stroke Recovery, 2075 Bayview Ave., Toronto, ON M4N 3M5, Canada ; Brain Sciences Research Program, Sunnybrook Research Institute, 2075 Bayview Ave., Toronto, ON M4N 3M5, Canada.
authors: Bradley J
authors: BJ
authors: MacIntosh
mesh_terms: D000368:Aged; D001284:Atrophy / Q000473:pathology / Q000503:physiopathology; D062485:Breath Holding; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D009929:Organ Size / Q000502:physiology
keywords: 3DMPRAGE, three-dimensional magnetization-prepared rapid gradient-echo; BH, breath hold; BOLD, blood oxygenation level dependent imaging; CThk, cortical thickness; CVR, cerebrovascular reactivity; Cerebrovascular reactivity; Cortical thickness; Diabetes; FLAIR, fluid attenuation inversion recovery; FLEX, fuzzy lesion extractor; HBA1C, hemoglobin A1C; HTN, hypertension; Hypertension; T2DM, type 2 diabetes mellitus; TICS, Telephone Interview for Cognitive Status; WMH, white matter hyperintensities