Retinal vessel abnormalities as a possible biomarker of brain volume loss in obese adolescents

Relationship between Overweight/Obesity and Social Communication in Autism Spectrum Disorder Children: Mediating Effect of Gray Matter Volume

With advances in medical diagnostic technology, the healthy development of children with autism spectrum disorder (ASD) is receiving more and more attention. In this article, the mediating effect of brain gray matter volume (GMV) between overweight/obesity and social communication (SC) was investigated through the analysis of the relationship between overweight/obesity and SC in autism spectrum disorder children. In total, 101 children with ASD aged 3-12 years were recruited from three special educational centers (Yangzhou, China). Overweight/obesity in children with ASD was indicated by their body mass index (BMI); the Social Responsiveness Scale, Second Edition (SRS-2) was used to assess their social interaction ability, and structural Magnetic Resonance Imaging (sMRI) was used to measure GMV. A mediation model was constructed using the Process plug-in to analyze the mediating effect of GMV between overweight/obesity and SC in children with ASD. The results revealed that: overweight/obesity positively correlated with SRS-2 total points (p = 0.01); gray matter volume in the left dorsolateral superior frontal gyrus (Frontal_Sup_L GMV) negatively correlated with SRS-2 total points (p = 0.001); and overweight/obesity negatively correlated with Frontal_Sup_L GMV (p = 0.001). The Frontal_Sup_L GMV played a partial mediating role in the relationship between overweight/obesity and SC, accounting for 36.6% of total effect values. These findings indicate the significant positive correlation between overweight/obesity and SC; GMV in the left dorsolateral superior frontal gyrus plays a mediating role in the relationship between overweight/obesity and SC. The study may provide new evidence toward comprehensively revealing the overweight/obesity and SC relationship.

Optic disc and retinal vascular features in first 6 years of Chinese children

Purpose

Retinal microvasculature plays an important role in children's fundus lesions and even in their later life. However, little was known on the features of normal retina in early life. The purpose of this study was to explore the normal retinal features in the first 6 years of life and provide information for future research.

Methods

Children, aged from birth to 6 years old and diagnosed with various unilateral ocular diseases were included. Venous phase fundus fluorescein angiography images with the optic disc at the center were collected. Based on the ResUNet convolutional neural network, optic disc and retinal vascular features in the posterior retina were computed automatically.

Results

A total of 146 normal eyes of 146 children were included. Among different age groups, no changes were shown in the optic disc diameter (y = -0.00002x + 1.362, R² = 0.025, p = 0.058). Retinal vessel density and fractal dimension are linearly and strongly correlated (r = 0.979, p < 0.001). Older children had smaller value of fractal dimension (y = -0.000026x + 1.549, R²= 0.075, p = 0.001) and narrower vascular caliber if they were less than 3 years old (y = -0.008x + 84.861, R²= 0.205, p < 0.001). No differences were in the density (y = -0.000007x + 0.134, R²= 0.023, p = 0.067) and the curvature of retinal vessels (lnC = -0.00001x - 4.657, R²= 0.001, p = 0.667).

Conclusions

Age and gender did not impact the optic disc diameter, vessel density, and vessel curvature significantly in this group of children. Trends of decreased vessel caliber in the first 3 years of life and decreased vessel complexity with age were observed. The structural characteristics provide information for future research to better understand the developmental origin of the healthy and diseased retina.

Retinal vessel diameters and function in cardiovascular risk and disease

In the last two decades evidence has gradually accumulated suggesting that the eye may be a unique window for cardiovascular risk stratification based on the assessment of subclinical damage of retinal microvascular structure and function. This can be facilitated by non-invasive analysis of static retinal vessel diameters and dynamic recording of flicker light-induced and endothelial function-related dilation of both retinal arterioles and venules. Recent new findings have made retinal microvascular biomarkers strong candidates for clinical implementation as reliable risk predictors. Beyond a review of the current evidence and state of research, the article aims to discuss the methodological benefits and pitfalls and to identify research gaps and future directions. Above all, the potential use for screening and treatment monitoring of cardiovascular disease risk are highlighted. The article provides fundamental comprehension of retinal vessel imaging by explaining anatomical and physiological essentials of the retinal microcirculation leading to a detailed description of the methodological approach. This allows for better understanding of the underlying retinal microvascular pathology associated with the prevalence and development of cardiovascular disease. A body of new evidence is presented on the clinical validity and predictive value of retinal vessel diameters and function for incidence cardiovascular disease and outcome. Findings in children indicate the potential for utility in childhood cardiovascular disease prevention, and the efficacy of exercise interventions highlight the treatment sensitivity of retinal microvascular biomarkers. Finally, coming from the availability of normative data, solutions for diagnostic challenges are discussed and conceptual steps towards clinical implementation are put into perspective.

High body weight-related retinal vasculopathy in children with obesity

PURPOSE

To investigate the foveal avascular zone (FAZ) and the microvascular alterations in both macula and peripapillary region in obese children.

METHODS

We included a total of 222 eyes of 111 children (54 obese children and 57 healthy subjects). Capillary vessel density (VD) of superficial (SCP) and deep (DCP) retinal capillary plexuses were measured in macular slabs. Peripapillary region was also evaluated. The FAZ parameters were measured based on the whole retinal slab. A commercial optical coherence tomography-angiography system was used.

RESULTS

The mean ages were 13.33 ± 2.55 years (range, 8-17) and 13.41 ± 2.90 years (range, 7-18) in patients with obesity and healthy controls, respectively (p = 0.84). The mean area of the FAZ were 0.278 ± 0.10 mm2 and 0.272 ± 0.11 mm2 in children with obesity and in control participants, respectively (p = 0.68). There were significant increases in the superior region of the parafoveal VD of SCP (p = 0.008 for superior hemisphere and p = 0.003 for superior quadrant). There was no significant difference in any measure of the macular DCP and peripapillary region (p > 0.05, for all).

CONCLUSION

Increased vascular density measurements were found in the superior part of the parafoveal region of SCP in children with obesity. The results of the study should be taken into consideration during the course of the disease to define whole systemic response to obesity in childhood and will be of interest for pediatrician's clinical practice.

Level of body fat relates to memory decline and interacts with age in its association with hippocampal and subcortical atrophy

Higher levels of body fat have shown adverse effects on multiple aspects of health, including cognitive and neuroanatomical changes. We tested the relationships of body fat levels and cholesterol to longitudinal age trajectories of subcortical gray matter volume (SCV), hippocampal volume (HCV), and episodic memory. Body fat was indexed by a concerted factor of BMI, visceral adipose tissue, percentage body fat, and total fat mass and was included in the analyses as a cross-sectional measure. We hypothesized that higher level of body fat would be related to steeper age trajectories of SCV, HCV, and memory. The sample consisted of 581 participants (20-83 years) with 942 magnetic resonance imaging and 945 memory examinations. Using generalized additive mixed models, a negative effect of body fat was found on SCV, HCV, and memory. Age and body fat interacted in their association with brain volume change. The results suggest that among cognitively healthy adults, there is a negative effect of higher body fat on SCV, HCV, and memory decline, an effect that increased with age for the neuroanatomical volumes.

Characteristics of the retinal microvasculature in association with cardiovascular risk markers in children with overweight, obesity and morbid obesity

To aim of this study was to evaluate characteristics of the retinal microvasculature, but particularly potential associations with classic and novel (endothelial function and low-grade inflammation)markers for cardiovascular risk, in a cohort of children with overweight and (morbid) obesity. Central retinal arteriolar equivalent(CRAE) and central retinal venular equivalent(CRVE) were assessed. CRAE was significantly lower and AVR significantly higher in children with morbid obesity than in children with overweight and normal weight(p < 0.01). CRVE did not differ significantly between the four weight categories. A multiple linear regression model with CRAE as dependent variable showed that only DBP z-score(β = −2.848,p = 0.029) and plasma glucose concentrations(β = 6.029,p = 0.019) contributed significantly to the variation in CRAE. Remarkably, despite a correlation between CRAE and circulating concentrations of the adhesion molecules VCAM-1 or ICAM-1, markers for inflammation and endothelial function did not contribute to the variation in CRAE. This is the first study showing in population of children with overweight and obesity that the retinal arteriolar microvasculature, but not venular diameter is aberrant, with increasing BMI z-score. CRAE was significantly associated with several cardiovascular risk markers, and multiple linear regression showed that a higher diastolic blood pressure z-score and lower fasting plasma glucose concentrations significantly contributed to the variance in CRAE.

Volumetric gray matter measures of amygdala and accumbens in childhood overweight/obesity

Objectives

Neuroimaging data suggest that pediatric overweight and obesity are associated with morphological alterations in gray matter (GM) brain structures, but previous studies using mainly voxel-based morphometry (VBM) showed inconsistent results. Here, we aimed to examine the relationship between youth obesity and the volume of predefined reward system structures using magnetic resonance (MR) volumetry. We also aimed to complement volumetry with VBM-style analysis.

Methods

Fifty-one Caucasian young subjects (32 females; mean age: 13.8±1.9, range: 10.2–16.5 years) were included. Subjects were selected from a subsample of the I.Family study examined in the Hungarian center. A T₁-weighted 1 mm³ isotropic resolution image was acquired. Age- and sex-standardized body mass index (zBMI) was assessed at the day of MRI and ~1.89 years (mean±SD: 689±188 days) before the examination. Obesity related GM alterations were investigated using MR volumetry in five predefined brain structures presumed to play crucial roles in body weight regulation (hippocampus, amygdala, accumbens, caudate, putamen), as well as whole-brain and regional VBM.

Results

The volumes of accumbens and amygdala showed significant positive correlations with zBMI, while their GM densities were inversely related to zBMI. Voxel-based GM mass also showed significant negative correlation with zBMI when investigated in the predefined amygdala region, but this relationship was mediated by GM density.

Conclusions

Overweight/obesity related morphometric brain differences already seem to be present in children/adolescents. Our work highlights the disparity between volume and VBM-derived measures and that GM mass (combination of volume and density) is not informative in the context of obesity related volumetric changes. To better characterize the association between childhood obesity and GM morphometry, a combination of volumetric segmentation and VBM methods, as well as future longitudinal studies are necessary. Our results suggest that childhood obesity is associated with enlarged structural volumes, but decreased GM density in the reward system.

The effect of obesity and insulin resistance on macular choroidal thickness in a pediatric population as assessed by enhanced depth imaging optical coherence tomography

BACKGROUND

The purpose of this study was to evaluate the macular choroidal thickness in obese children with and without insulin resistance (IR).

METHODS

Thirty-six patients with obesity and 26 healthy volunteers were included in this cross-sectional study. The choroidal thickness was measured with enhanced depth imaging optical coherence tomography (EDI-OCT) at the fovea and at positions 500 μm, 1000 μm, 1500 μm nasal and temporal to the fovea. The choroidal thickness measurements of the groups were compared and the correlation between the homeostasis model assessment of insulin resistance (HOMA-IR) and choroidal thickness values was evaluated.

RESULTS

The average choroidal thickness in the obese group was significantly lower than that of controls at locations 1000 μm (303.31±58.52 vs. 340.58±69.47, p=0.026) and 1500 μm (284.14±65.06 vs. 336.85±71.37, p=0.004) temporal to the fovea. A subgroup analysis depending on the presence of IR revealed that the choroidal thickness measurements at all positions were thinner in obese children without IR compared to children with IR and healthy controls. This thinning reached a statistical significance at locations 500 μm temporal, 1000 μm temporal and 1500 μm temporal to the fovea (p=0.03, p=0.009 and p=0.006; respectively). There was a moderate correlation between the choroidal thickness measurements and HOMA-IR values (r-values between 0.37 and 0.48; p<0.05).

CONCLUSIONS

Our results suggest that obesity and IR may have an influence on the choroidal thickness in children. Longitudinal studies will clarify whether these choroidal changes are progressive and are a sign of microvascular dysfunction in childhood obesity.

Associations of leptin, insulin and lipids with retinal microvasculature in children and adolescents

BACKGROUND

We investigated whether cardiometabolic risk factors measured in serum (total cholesterol [TC], high-density lipoprotein [HDL], triglyceride, leptin, insulin, glucose and insulin resistance) are associated with the retinal microvasculature, a marker of cardiovascular aging, in healthy children and adolescents. Moreover, we tested whether these associations are due to direct biological effects or more indirectly due to adiposity-related side effects.

METHODS

We recruited 168 healthy Flemish children (7-16 years old, 54.8% boys). Blood samples and retinal photographs were taken during clinical examinations. Arteriolar and venular vessel calibers were calculated using a semi-automated computer program. Multivariable regression models were used and adjusted for age, sex, mean arterial pressure (MAP) and alternate retinal caliber. In a second step, we adjusted for body mass index z-score (zBMI).

RESULTS

Only continuous serum leptin was associated with retinal parameters, i.e. wider arterioles; however, this disappeared after adjustment for zBMI. Children with high cardiometabolic risk factors (>90th percentile for serum leptin, insulin and insulin resistance) had wider arterioles compared to children with lower concentrations, even after additional adjustment for zBMI. No significant associations were found with lipids.

CONCLUSIONS

In this healthy population of children and adolescents, the hormones insulin and leptin and insulin resistance were associated with retinal microvasculature alterations, mainly in children with high cardiometabolic factors (>90th percentile), while lipids were not. These associations were independent of zBMI.

Insulin Sensitivity and Inflammation Mediate the Impact of Fitness on Cerebrovascular Health in Adolescents

BACKGROUND/OBJECTIVES

To investigate in adolescents the relationships between retinal vessel diameter, physical fitness, insulin sensitivity, and systemic inflammation.

METHODS

We evaluated 157 adolescents, 112 with excessive weight and 45 lean, all without type 2 diabetes mellitus. All received detailed evaluations, including measurements of retinal vessel diameter, insulin sensitivity, levels of inflammation, and physical fitness.

RESULTS

Overweight/obese adolescents had significantly narrower retinal arteriolar and wider venular diameters, significantly lower insulin sensitivity, and physical fitness. They also had decreased levels of anti-inflammatory and increased levels of proinflammatory markers as well as an overall higher inflammation balance score. Fitness was associated with larger retinal arteriolar and narrower venular diameters and these relationships were mediated by insulin sensitivity. We demonstrate that inflammation also mediates the relationship between fitness and retinal venular, but not arterial diameter; insulin sensitivity and inflammation balance score jointly mediate this relationship with little overlap in their effects.

CONCLUSIONS

Increasing fitness and insulin sensitivity and reducing inflammation among adolescents carrying excess weight may improve microvascular integrity. Interventions to improve physical fitness and insulin function and reduce inflammation in adolescents, a group likely to benefit from such interventions, may reduce not only cardiovascular disease in middle age, but also improve cerebrovascular function later in life.

Brain gray and white matter differences in healthy normal weight and obese children

PURPOSE

To compare brain gray and white matter development in healthy normal weight and obese children.

METHODS

Twenty-four healthy 8- to 10-year-old children whose body mass index was either <75(th) percentile (normal weight) or >95(th) percentile (obese) completed an MRI examination which included T1-weighted three-dimensional structural imaging and diffusion tensor imaging (DTI). Voxel-based morphometry was used to compare the regional gray and white matter between the normal weight and obese children, and tract-based spatial statistics was used to compare the water diffusion parameters in the white matter between groups.

RESULTS

Compared with normal weight children, obese children had significant (P < 0.05, family wise error corrected) regional gray matter reduction in the right middle temporal gyrus, left and right thalami, left superior parietal gyrus, left pre/postcentral gyri, and left cerebellum. Obese children also had higher white matter (P < 0.05, corrected) in multiple regions in the brain and higher DTI measured fractional anisotropy (FA) values (P < 0.05, corrected) in part of the left brain association and projection fibers. There was no difference in mean diffusivity at P < 0.05, corrected. DTI eigenvalues suggested that the FA differences were likely from decreased radial diffusivity (P < 0.1, corrected) and there was no change in axial diffusivity (corrected P > 0.35 for all voxels).

CONCLUSION

Our results indicated that obese but otherwise healthy children have different regional gray and white matter development in the brain and differences in white matter microstructures compared with healthy normal weight children.

Retinal vessel alterations and cerebral white matter microstructural damage in obese adolescents with metabolic syndrome

IMPORTANCE

Cerebral white matter (WM) damage has been reported in childhood obesity and in metabolic syndrome (MetS) but mechanisms remain unclear.

OBJECTIVES

To ascertain whether adolescents with MetS have retinal vessel alterations and if the anticipated reductions in retinal arteriolar diameter are associated with diminished cerebral WM microstructural integrity and to test a model for vascular etiology of the WM abnormalities.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of the brain correlates of obesity and related metabolic disease in youths. This study was conducted at the Brain, Obesity, and Diabetes Laboratory, New York University School of Medicine, New York. Thirty-nine obese adolescents with MetS and 51 matched adolescents without MetS received comprehensive endocrine, neuropsychological, retinal vessel, and diffusion tensor imaging-based cerebral WM evaluations.

MAIN OUTCOMES AND MEASURES

Retinal arteriolar diameter, cerebral WM microstructural integrity, waist circumference, and insulin resistance.

RESULTS

Obese adolescents with MetS had significant reductions in retinal arteriolar diameter relative to adolescents without MetS (mean [SD] central retinal arteriolar equivalent, 182.35 [16.10] vs. 198.62 [19.03] μm, respectively; P < .001). The greater the number of MetS criteria present, the greater the reduction was in retinal arteriolar diameter (β = -8.61; ∆r2 = 0.335; ∆F1,83 = 70.79; P < .001). We found that abdominal obesity (waist circumference) was the strongest MetS component related to reductions in retinal arteriolar diameter (rp[85] = -0.661; P < .001), and importantly, for the first time to our knowledge, we demonstrated that its effect was partially mediated by comorbid insulin resistance (indirect effect = -0.1355 [95% CI, -0.2471 to -0.0593]; Z = -2.56; P = .01). Consistent with our prior report of nondiabetic adolescents with MetS, we also uncovered cerebral WM microstructural damage. These subtle WM changes were associated with reductions in retinal arteriolar diameter, a proxy for cerebral microvascular health (3150 voxels or 3.15 cm3; P < .001). Importantly, some of the WM regions showing lower microstructural integrity also demonstrated associations with retinal arteriolar diameter, suggesting that the observed WM pathology is likely vascular in nature.

CONCLUSIONS AND RELEVANCE

We document, for the first time to our knowledge, the associations between retinal vessel alterations and subclinical WM pathology among obese adolescents with MetS. This suggests that the subtle WM pathology in adolescents with MetS may have a vascular origin. Future work should include direct assessments of cerebral microvascular health.

Is Alzheimer's disease related to metabolic syndrome? A Wnt signaling conundrum

Alzheimer's disease (AD) is the most common cause of dementia, affecting more than 36 million people worldwide. AD is characterized by a progressive loss of cognitive functions. For years, it has been thought that age is the main risk factor for AD. Recent studies suggest that life style factors, including nutritional behaviors, play a critical role in the onset of dementia. Evidence about the relationship between nutritional behavior and AD includes the role of conditions such as obesity, hypertension, dyslipidemia and elevated glucose levels. The coexistence of some of these cardio-metabolic risk factors is generally known as metabolic syndrome (MS). Some clinical studies support the role of MS in the onset of AD. However, the cross-talk between the molecular signaling implicated in these disorders is unknown. In the present review, we focus on the molecular correlates that support the relationship between MS and the onset of AD. We also discuss relevant issues such as the role of leptin, insulin and renin-angiotensin signaling in the brain and the possible role of Wnt signaling in both MS and AD. We discuss the evidence supporting the use of ob/ob mice, high-fructose diets, aortic coarctation-induced hypertension and Octodon degus, which spontaneously develops β-amyloid deposits and metabolic derangements, as suitable animal models to address the relationships between MS and AD. Finally, we examine emergent data supporting the role of Wnt signaling in the modulation of AD and MS, implicating this pathway as a therapeutic target in both conditions.

Flavonol-rich dark cocoa significantly decreases plasma endothelin-1 and improves cognition in urban children

Air pollution exposures are linked to systemic inflammation, cardiovascular and respiratory morbidity and mortality, neuroinflammation and neuropathology in young urbanites. In particular, most Mexico City Metropolitan Area (MCMA) children exhibit subtle cognitive deficits, and neuropathology studies show 40% of them exhibiting frontal tau hyperphosphorylation and 51% amyloid-β diffuse plaques (compared to 0% in low pollution control children). We assessed whether a short cocoa intervention can be effective in decreasing plasma endothelin 1 (ET-1) and/or inflammatory mediators in MCMA children. Thirty gram of dark cocoa with 680 mg of total flavonols were given daily for 10.11 ± 3.4 days (range 9–24 days) to 18 children (10.55 years, SD = 1.45; 11F/7M). Key metabolite ratios in frontal white matter and in hippocampus pre and during cocoa intervention were quantified by magnetic resonance spectroscopy. ET-1 significantly decreased after cocoa treatment (p = 0.0002). Fifteen children (83%) showed a marginally significant individual improvement in one or both of the applied simple short memory tasks. Endothelial dysfunction is a key feature of exposure to particulate matter (PM) and decreased endothelin-1 bioavailability is likely useful for brain function in the context of air pollution. Our findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer's and Parkinson's diseases.

Cerebral white matter and retinal arterial health in hypertension and type 2 diabetes mellitus

We examined 33 hypertensive (22 with comorbid type 2 diabetes mellitus (T2DM)) and 29 normotensive (8 with T2DM) middle-aged and elderly adults, comparable in age and education. Relative to normotensive participants, those with hypertension, in addition to a higher prevalence of periventricular white matter (WM) lesions, had significantly lower WM microstructural integrity of major fiber tracts as seen with MRI-based diffusion tensor imaging. Among participants with hypertension, those with co-morbid T2DM (n = 22) had more widespread WM pathology than those without T2DM (n = 11). Furthermore and consistent with previous research, both hypertension and T2DM were related to decreased retinal arterial diameter. Further exploratory analysis demonstrated that the observed retinal arteriolar narrowing among individual with hypertension was associated with widespread subclinical losses in WM microstructural integrity and these associations were present predominantly in the frontal lobe. We found that T2DM adds to the damaging effects of hypertension on cerebral WM, and notably these effects were independent of age and body mass index. Given that the decrease in retinal arteriolar diameter may be a biomarker for parallel pathology in cerebral arterioles, our data suggest that the frontal lobe may be particularly vulnerable to microvascular damage in the presence of hypertension and T2DM.