Functional network centrality in obesity: A resting-state and task fMRI study.

Obesity is associated with structural and functional alterations in brain areas that are often functionally distinct and anatomically distant. This suggests that obesity is associated with differences in functional connectivity of regions distributed across the brain. However, studies addressing whole brain functional connectivity in obesity remain scarce. Here, we compared voxel-wise degree centrality and eigenvector centrality between participants with obesity (n=20) and normal-weight controls (n=21). We analyzed resting state and task-related fMRI data acquired from the same individuals. Relative to normal-weight controls, participants with obesity exhibited reduced degree centrality in the right middle frontal gyrus in the resting-state condition. During the task fMRI condition, obese participants exhibited less degree centrality in the left middle frontal gyrus and the lateral occipital cortex along with reduced eigenvector centrality in the lateral occipital cortex and occipital pole. Our results highlight the central role of the middle frontal gyrus in the pathophysiology of obesity, a structure involved in several brain circuits signaling attention, executive functions and motor functions. Additionally, our analysis suggests the existence of task-dependent reduced centrality in occipital areas; regions with a role in perceptual processes and that are profoundly modulated by attention.

The interaction effect between BDNF val66met polymorphism and obesity on executive functions and frontal structure.

The prevalence of obesity is increasing worldwide. Previous research has shown a relationship between obesity and both executive functioning alterations and frontal cortex volume reductions. The Brain Derived Neurotrophic Factor val66met polymorphism, involved in eating behavior, has also been associated with executive functions and prefrontal cortex volume, but to date it has not been studied in relation to obesity. Our aim is to elucidate whether the interaction between the Brain Derived Neurotrophic Factor val66met polymorphism and obesity status influences executive performance and frontal-subcortical brain structure. Sixty-one volunteers, 34 obese and 27 controls, age range 12-40, participated in the study. Participants were assigned to one of two genotype groups (met allele carriers, n = 16, or non-carriers, n = 45). Neuropsychological assessment comprised the Trail Making Test, the Stroop Test and the Wisconsin Card Sorting Test, all tasks that require response inhibition and cognitive flexibility. Subjects underwent magnetic resonance imaging in a Siemens TIM TRIO 3T scanner and images were analyzed using the FreeSurfer software. Analyses of covariance controlling for age and intelligence showed an effect of the obesity-by-genotype interaction on perseverative responses on the Wisconsin Card Sorting Test as well as on precentral and caudal middle frontal cortical thickness: obese met allele carriers showed more perseverations on the Wisconsin Card Sorting Test and lower frontal thickness than obese non-carriers and controls. In conclusion, the Brain Derived Neurotrophic Factor may play an important role in executive functioning and frontal brain structure in obesity.

Frontal cortical thinning and subcortical volume reductions in early adulthood obesity.

Obesity depends on homeostatic and hedonic food intake behavior, mediated by brain plasticity changes in cortical and subcortical structures. The aim of this study was to investigate cortical thickness and subcortical volumes of regions related to food intake behavior in a healthy young adult sample with obesity. Thirty-seven volunteers, 19 with obesity (age=33.7±5.7 (20-39) years body-mass index (BMI)=36.08±5.92 (30.10-49.69)kg/m(2)) and 18 controls (age=32.3±5.9 (21-40) years; BMI=22.54±1.94 (19.53-24.97)kg/m(2)) participated in the study. Patients with neuropsychiatric or biomedical disorders were excluded. We used FreeSurfer software to analyze structural magnetic resonance images (MRI) and obtain global brain measures, cortical thickness and subcortical volume estimations. Finally, correlation analyses were performed for brain structure data and obesity measures. There were no between-group differences in age, gender, intelligence or education. Results showed cortical thickness reductions in obesity in the left superior frontal and right medial orbitofrontal cortex. In addition, the obesity group had lower ventral diencephalon and brainstem volumes than controls, while there were no differences in any other subcortical structure. There were no statistically significant correlations between brain structure and obesity measures. Overall, our work provides evidence of the structural brain characteristics associated with metabolically normal obesity. We found reductions in cortical thickness, ventral diencephalon and brainstem volumes in areas that have been implicated in food intake behavior.

Alterations of the salience network in obesity: a resting-state fMRI study.

Obesity is a major health problem in modern societies. It has been related to abnormal functional organization of brain networks believed to process homeostatic (internal) and/or salience (external) information. This study used resting-state functional magnetic resonance imaging analysis to delineate possible functional changes in brain networks related to obesity. A group of 18 healthy adult participants with obesity were compared with a group of 16 lean participants while performing a resting-state task, with the data being evaluated by independent component analysis. Participants also completed a neuropsychological assessment. Results showed that the functional connectivity strength of the putamen nucleus in the salience network was increased in the obese group. We speculate that this abnormal activation may contribute to overeating through an imbalance between autonomic processing and reward processing of food stimuli. A correlation was also observed in obesity between activation of the putamen nucleus in the salience network and mental slowness, which is consistent with the notion that basal ganglia circuits modulate rapid processing of information.

Dopamine genes (DRD2/ANKK1-TaqA1 and DRD4-7R) and executive function: their interaction with obesity.

Obesity is a multifactorial disease caused by the interaction between genotype and environment, and it is considered to be a type of addictive alteration. The A1 allele of the DRD2/ANKK1-TaqIA gene has been associated with addictive disorders, with obesity and with the performance in executive functions. The 7 repeat allele of the DRD4 gene has likewise been associated with the performance in executive functions, as well as with addictive behaviors and impulsivity. Participants were included in the obesity group (N = 42) if their body mass index (BMI) was equal to or above 30, and in the lean group (N = 42) if their BMI was below 25. The DRD2/ANKK1-TaqIA and DRD4 VNTR polymorphisms were obtained. All subjects underwent neuropsychological assessment. Eating behavior traits were evaluated. The 'DRD2/ANKK1-TaqIA A1-allele status' had a significant effect on almost all the executive variables, but no significant 'DRD4 7R-allele status' effects were observed for any of the executive variables analyzed. There was a significant 'group' x 'DRD2/ANKK1-TaqIA A1-allele status' interaction effect on LN and 'group' x 'DRD4 7R-allele status' interaction effect on TMT B-A score. Being obese and a carrier of the A1 allele of DRD2/ANKK1-TaqIA or the 7R allele of DRD4 VNTR polymorphisms could confer a weakness as regards the performance of executive functions.

[Ophthalmic disease in diabetes mellitus: management from primary health care]. / Oftalmopatía en la diabetes mellitus: detección desde la Atención Primaria de salud.

OBJECTIVE: To study the feasibility of a basic ophthalmological examination for the eye disease in diabetic patients by Primary Health Care (PHC). PATIENTS AND METHODS: A multi-centre prospective study. A sample of 712 type 2 diabetics. INTERVENTIONS: Visual acuity examination, intraocular pressure measurement and the eye fundus photograph with a non-mydriatic camera taken by an optometrist. The interpretation and subsequent referral to an ophthalmology department by ophthalmologists and general practitioners (GP). RESULTS: Visual acuity deficiency: GP, 43.7%; ophthalmologist, 36.1%; concordance, 70%; glaucoma suspicion: GP, 8.8%; ophthalmologist, 7.6%; concordance, 94%; diabetic retinopathy: GP, 28.2%; ophthalmologist, 13.4%; concordance, 78%. Ophthalmology Department referral: GP, 56.8%; ophthalmologist, 41.3% (P=0.001). CONCLUSIONS: Agreement between GP and ophthalmologist leads to a reliable ophthalmological examination of the diabetic patient in PHC. Despite an over-diagnosis and 16% of non-justified referrals by the GP, Ophthalmology Department referral is avoided in almost half of the diabetic patients.

[Cardiovascular risk factors: a follow up study in a non-diabetic population]. / Factores de riesgo cardiovascular: estudio de seguimiento en población no diabética.

OBJECTIVES: To evaluate the cardiovascular risk factors (CVRF), their relationship with insulin resistance (IR) and pancreatic beta-cell (PBC) function in a known non-diabetic population, and to follow its progress over a period of 5 years. DESIGN: Nested case-control study developed in two phases: the identification and characterisation of the cohort to study and the follow up. SETTING: Urban Primary Care Centre. PARTICIPANTS: A non-diabetic population sample from 40 to 70 years. MAIN MEASUREMENTS: History of CVRF, physical examination (body mass index, abdominal girth, blood pressure), laboratory tests (fasting glucose, lipid profile and fasting insulin) and calculation of IR and PBC using the Homeostasis Model Assessment mathematical program. RESULTS: Identification phase: 326 subjects. CVRF 32.5% dyslipaemia, 28.8% smoking, 28.2% obesity and 24.8% increased blood pressure. Number of CVRF: 37.7% had one, 21.5% two, 10.1% three and 2.1% four. Relationship between number of CVRF and IR. More IR in hypertensive, obese and dyslipaemic subjects. Follow up phase (5 years): 121 subjects. Significant proportion of dyslipaemia and impaired fasting glucose (IFG). CONCLUSIONS: The most common CVRF were dyslipaemia, smoking, obesity and raised blood pressure, with more IR in patients with high blood pressure, dyslipaemia and obesity and a higher number of CVRF in comparison with the rest of the population. At five years of follow up, an increase was only observed in the number of dyslipaemia and IFG and no reduction was achieved in the percentage of active smokers.