Browsing by Subject "Brain imaging"

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Open Access
Resting-state network dysconnectivity in ADHD: a system-neuroscience-based meta-analysis
(Taylor and Francis, 2020) Sütçübaşı, B.; Metin, B.; Kurban, Mustafa Kerem; Metin, Z. E.; Beşer, B.; Sonuga-Barke, E.
Objectives: Neuroimaging studies report altered resting-state functional connectivity in attention deficit/hyperactivity disorder (ADHD) across multiple brain systems. However, there is inconsistency among individual studies. Methods: We meta-analyzed seed-based resting state studies of ADHD connectivity within and between four established resting state brain networks (default mode, cognitive control, salience, affective/motivational) using Multilevel Kernel Density Analysis method. Results: Twenty studies with 944 ADHD patients and 1121 controls were included in the analysis. Compared to controls, ADHD was associated with disrupted within-default mode network (DMN) connectivity – reduced in the core (i.e. posterior cingulate cortex seed) but elevated in the dorsal medial prefrontal cortex sub-system (i.e. temporal pole-inferior frontal gyrus). Connectivity was elevated between nodes in the cognitive control system. When the analysis was restricted to children and adolescents, additional reduced connectivity was detected between DMN and cognitive control and affective/motivational and salience networks. Conclusions: Our data are consistent with the hypothesis that paediatric ADHD is a DMN-dysconnectivity disorder with reduced connectivity both within the core DMN sub-system and between that system and a broad set of nodes in systems involved in cognition and motivation.
Open Access
Structural imaging of the brain reveals decreased total brain and total gray matter volumes in obese but not in lean women with polycystic ovary syndrome compared to body mass index-matched counterparts
(Taylor and Francis Ltd, 2017) Saydam, B. O.; Has, A. C.; Bozdag, G.; Oguz, K. K.; Yildiz, B. O.
Purpose: To detect differences in global brain volumes and identify relations between brain volume and appetite-related hormones in women with polycystic ovary syndrome (PCOS) compared to body mass index-matched controls. Methods: Forty subjects participated in this study. Cranial magnetic resonance imaging and measurements of fasting ghrelin, leptin and glucagon-like peptide 1 (GLP-1), as well as GLP-1 levels during mixed-meal tolerance test (MTT), were performed. Results: Total brain volume and total gray matter volume (GMV) were decreased in obese PCOS compared to obese controls (p < 0.05 for both) whereas lean PCOS and controls did not show a significant difference. Secondary analyses of regional brain volumes showed decreases in GMV of the caudate nucleus, ventral diencephalon and hippocampus in obese PCOS compared to obese controls (p < 0.05 for all), whereas lean patients with PCOS had lower GMV in the amygdala than lean controls (p < 0.05). No significant relations were detected between structural differences and measured hormone levels at baseline or during MTT. Conclusion: This study, investigating structural brain alterations in PCOS, suggests volumetric reductions in global brain areas in obese women with PCOS. Functional studies with larger sample size are needed to determine physiopathological roles of these changes and potential effects of long-term medical management on brain structure of PCOS. © 2017 Informa UK Limited, trading as Taylor & Francis Group.