Cerebrovascular damage in late-life depression is associated with structural and functional abnormalities of subcutaneous small arteries
Late-life depression is increasingly viewed as a vascular illness because of patients exhibiting characteristic white matter brain lesions and in vivo large artery endothelial dysfunction. However, the "vascular depression" hypothesis pertains to the microvasculature, and this circulation has not been studied in this context. Our objective was to examine structure and function of small subcutaneous arteries in patients with late-life depression. Thus, 16 patients aged 71.8±4.0 years with late-life depression were compared with 15 control participants aged 72.1±5.9 years. There were similar cardiovascular profiles between the 2 groups. All of the participants underwent MRI brain scans and subcutaneous gluteal fat biopsy from which small arteries were isolated and studied using pressure myography. Cerebral microvascular damage in depressed patients was confirmed by assessment of basal ganglia Virchow-Robin space scores (depressed patients 3.9±1.7 versus controls: 2.5±1.6; P=0.01). Contractility to norepinephrine was equivalent in both groups, but relaxation of the small arteries to acetylcholine was significantly reduced in depressed patients (84.0±4.0%) compared with control participants (96.0±1.4%; P=0.012). This difference in arterial relaxation was reduced but not entirely eliminated when NO synthase was inhibited. Depressed patients also exhibited hypertrophic wall growth with an increase in medial cross-sectional area (P=0.035, multiple ANOVA and wall thickness; P=0.04, multiple ANOVA). In conclusion, despite similar cardiovascular profiles, depressed patients with cerebral microvascular damage show abnormalities of subcutaneous small artery structure and function.