Associations of sleep with gray matter volume and their implications for academic achievement, executive function and intelligence in children with overweight/obesity

Altered structural node of default mode network mediated general cognitive ability in young adults with obesity

BACKGROUND

Obesity, characterized by excessive adiposity, is associated with brain structural abnormalities. Nevertheless, the relationships between altered structural nodes of default mode network (DMN), body mass index (BMI), general cognitive ability remained unclear in young adults.

METHODS

In this study, we divided a large sample of young adults into three BMI-based groups. We then conducted one-way analyses of variance and post-hoc tests with Bonferroni corrections to investigate abnormal structural brain regions associated with obesity. Furthermore, mediation effects models were built to explore whether the structural alterations influenced the relationship between BMI and general cognitive ability.

RESULTS

Compared to their lean and overweight counterparts, young adults with obesity exhibited significantly lower general cognitive ability, higher impulsivity traits, and worse sleep quality. Furthermore, compared with lean group, young adults with obesity exhibited altered cortical thickness of both the left temporal pole and right superior parietal lobule, and abnormal cortical surface area (CSA) of the left entorhinal cortex (EC), a hub within DMN. Moreover, CSA of the left EC mediated the relationship between BMI and general cognitive ability.

CONCLUSION

Obesity was linked to altered structural node of DMN, which mediated general cognitive ability in young adults. These findings indicated the negative effect of obesity on DMN and general cognitive ability in young adults.

Inhibitory control mediates the association between body mass index and math performance in children: A cross-sectional study

BACKGROUND

Overweight and obesity affect more than 18% of children and adolescents in the world. Obesity-related associations with brain morphology might be associated with reduced efficiency of inhibitory control. This association highlights a possible mechanism by which obesity impacts intelligence and academic achievement. Prior work indicates a mediating effect of inhibitory control on the relationship between body mass index (BMI) and intelligence and academic achievement. However, although obesity is associated with impaired math performance, we do not know whether inhibitory control also mediates the relationship between BMI and math performance. This study tests the hypothesis that inhibitory control statistically mediates the relationship between BMI and math performance.

METHODS

161 children (9 to 13 years old, 80 female) participated in the present study. We evaluated BMI; math performance, in a test composed of 20 arithmetic equations of the type x = (a × b) - c; and inhibitory control through the Flanker test. We carried out Spearman correlation tests, hierarchical multiple linear regression, and tested the confidence of the model where inhibitory control statistically mediates the indirect association between BMI and math performance. Mediation analysis in this cross-sectional study aimed to improve understanding of indirect relationships and offer insights into possible causal connections.

RESULTS

Better math performance and lower BMI were associated with greater accuracy on the inhibitory control test and greater accuracy on the inhibitory control test was associated with better performance on math test. We found an indirect association between higher BMI in children and impairments in math performance, that was mediated by inhibitory control (a: -0.008, p = 0.025; b: 7.10, p = 0.0004; c: 0.05, p = 0.592; c': 0.11, p = 0.238; Indirect Effect: -0.0599, 95% CI: -0.13, -0.005).

CONCLUSIONS

An indirect association between higher body mass indices in children and impairments in math performance was detected, through the impact that BMI has on inhibitory control.

Sleep Behaviors and the Shape of Subcortical Brain Structures in Children with Overweight/Obesity: A Cross-Sectional Study

OBJECTIVES

To examine the relationship between sleep and subcortical brain structures using a shape analysis approach.

METHODS

A total of 98 children with overweight/obesity (10.0 ± 1.1 y, 59 boys) were included in the cross-sectional analyses. Sleep behaviors (i.e., wake time, sleep onset time, total time in bed, total sleep time, sleep efficiency, and wakening after sleep onset) were estimated with wrist-worn accelerometers. The shape of the subcortical brain structures was acquired by magnetic resonance imaging. A partial correlation permutation approach was used to examine the relationship between sleep behaviors and brain shapes.

RESULTS

Among all the sleep variables studied, only total time in bed was significantly related to pallidum and putamen structure, such that those children who spent more time in bed had greater expansions in the right and left pallidum (211-751 voxels, all p's <0.04) and right putamen (1783 voxels, p = 0.03).

CONCLUSIONS

These findings suggest that more time in bed was related to expansions on two subcortical brain regions in children with overweight/obesity.

Examining the associations between attention-deficit/hyperactivity disorder, sleep problems, and other mental health conditions in adolescents

Adolescents with attention-deficit/hyperactivity disorder (ADHD) often experience greater sleep difficulties compared to those without. However, findings are mixed, and other mental health conditions are often overlooked. This study aimed to examine the relationship between sleep problems, ADHD, and other mental health conditions in a sample of adolescents. Data from 373 adolescents aged 10-19 years was used as part of the wider 'Healthy Brain Network' study, which targets children and adolescents experiencing mental health and neurodevelopmental difficulties. Mental health conditions were assessed via a comprehensive assessment. Sleep was measured by self- and parent-report, as well as via up to a month of actigraphy data. Actigraphy data were analysed using mixed-methods modelling, while subjective sleep data were analysed using multiple regression. Subjectively-reported sleep was generally worse in adolescents who had ADHD and other mental health conditions compared to those with ADHD but no other conditions. There were no associations between ADHD status and objective sleep measures or self-reported measures, but a significant association was found between ADHD status and parent-reported sleep difficulties, even when accounting for other conditions. Parent-reported sleep problems were associated not only with ADHD, but also with anxiety, depression, and externalising disorders. The strength of association between ADHD and sleep problems is potentially not as strong as previously thought when considering the role of other mental health conditions. Clinicians should consider the role of other mental health conditions when sleep problems are present, and vice versa. The study also highlights the importance of comprehensive, multi-informant assessment of mental health conditions, including sleep.

Effects of exercise on sleep in children with overweight/obesity: a randomized clinical trial

OBJECTIVE

The objective of this study was to examine the chronic effects of a 20-week exercise training program on device-assessed sleep and sleep-disordered breathing; and to determine whether participating in a session of the exercise program had effects on device-assessed sleep the subsequent night in children with overweight/obesity.

METHODS

A randomized clinical trial was conducted from November 2014 to June 2016. A total of 109 children (age 8-11 years) with overweight/obesity were randomized into an exercise training or control group. The exercise program included aerobic and resistance training 3 to 5 days/week. The control group participants continued their usual lifestyle. Device-assessed sleep outcomes were measured using wrist-worn actigraphy at baseline, in the middle of the exercise program (10th week), and at postintervention for seven consecutive days (24 h/day), and sleep-disordered breathing was measured via the Pediatric Sleep Questionnaire.

RESULTS

The exercise training program had a statistically significant effect on wake after sleep onset time (-10.8 min/day, -0.5 SDs, p = 0.040). No other chronic or acute effects (i.e., the subsequent night of attending a session of the exercise training program) were observed on the remaining sleep outcomes.

CONCLUSIONS

A 20-week exercise training program reduced wake after sleep onset time in children with overweight/obesity. Future randomized trials that include a sample of children with poor sleep health at baseline are needed to better appreciate the role of exercise in sleep health.

Brain functional and structural magnetic resonance imaging of obesity and weight loss interventions

Obesity has tripled over the past 40 years to become a major public health issue, as it is linked with increased mortality and elevated risk for various physical and neuropsychiatric illnesses. Accumulating evidence from neuroimaging studies suggests that obesity negatively affects brain function and structure, especially within fronto-mesolimbic circuitry. Obese individuals show abnormal neural responses to food cues, taste and smell, resting-state activity and functional connectivity, and cognitive tasks including decision-making, inhibitory-control, learning/memory, and attention. In addition, obesity is associated with altered cortical morphometry, a lowered gray/white matter volume, and impaired white matter integrity. Various interventions and treatments including bariatric surgery, the most effective treatment for obesity in clinical practice, as well as dietary, exercise, pharmacological, and neuromodulation interventions such as transcranial direct current stimulation, transcranial magnetic stimulation and neurofeedback have been employed and achieved promising outcomes. These interventions and treatments appear to normalize hyper- and hypoactivations of brain regions involved with reward processing, food-intake control, and cognitive function, and also promote recovery of brain structural abnormalities. This paper provides a comprehensive literature review of the recent neuroimaging advances on the underlying neural mechanisms of both obesity and interventions, in the hope of guiding development of novel and effective treatments.

Early life factors and hippocampal functional connectivity in children with overweight/obesity

OBJECTIVE

We investigated the association of anthropometric neonatal data (birth length and birth weight) and breastfeeding practices (exclusive and any breastfeeding) with hippocampal functional connectivity and its academic implication in children with overweight/obesity.

METHODS

Ninety six children with overweight/obesity aged 8-11 years (10.01 ± 1.14), from the ActiveBrains project were included in this cross-sectional study. Anthropometric neonatal data were collected from birth records, whereas breastfeeding practices were reported by parents. A 3.0 Tesla Siemens Magnetom Tim Trio system was used to acquire T1-weighted and resting-state functional magnetic resonance images. Academic performance was assessed by the Woodcock-Muñoz standardized test. Hippocampal seed-based methods with post-hoc regression analyses were performed. Analyses were considered significant when surpassing Family-Wise Error corrections.

RESULTS

Birth weight showed a positive association with the connectivity between the hippocampus and the pre- and postcentral gyri, and the cerebellum. In addition, breastfeeding was negatively associated with the connectivity between the hippocampus and the primary motor cortex and the angular gyrus. Any breastfeeding, in turn, showed a positive association with the connectivity between the hippocampus and the middle temporal gyrus. None of the connectivity outcomes related to early life factors was coupled with better academic abilities (all p > 0.05).

CONCLUSIONS

Our findings suggest that birth weight at birth and breastfeeding are associated with hippocampal connectivity in children with overweight/obesity. Despite this, how the results relate to academic performance remains a matter of speculation. Our findings suggest that clinicians should recognize the importance early life factors for potentially avoiding consequences on offspring's brain development.

Physical activity, sedentary time, and fitness in relation to brain shapes in children with overweight/obesity: Links to intelligence

OBJECTIVES

To examine the association between physical activity, sedentary time, and physical fitness with the shapes of subcortical brain structures in children with overweight/obesity. Further, we analyzed whether differences in the shapes of subcortical brain structures were related to intelligence. We hypothesized that those children with higher physical activity levels, lower sedentary time, and better fitness, would show greater expansion of the brain regions analyzed, and these expansions would be associated with higher intelligence.

STUDY DESIGN

100 children (10.0 ± 1.1 years, 40 girls) were included in the analyses. Physical activity and sedentary time were measured by accelerometry, and physical fitness was evaluated by a fitness battery. Shapes of subcortical brain structures were assessed by magnetic resonance imaging. Intelligence was measured by the Kaufmann Brief Intelligence test.

RESULTS

Physical activity was related to expansion of the right/left pallidum, right/left putamen, and right thalamus (p < 0.05). Higher sedentary time was related to contraction of the left thalamus and right nucleus accumbens (p < 0.05). Higher levels of cardiorespiratory fitness were associated with expansion of the right amygdala (p = 0.022). Greater strength in the upper-limb was related to expansion of the right/left pallidum and the left nucleus accumbens (p < 0.038), and contraction of the left amygdala (p = 0.030). Better speed-agility was associated with expansion of the left nucleus accumbens (p = 0.036). Physical activity- and fitness-related expansion of the right pallidum was associated with higher intelligence (all p < 0.05).

CONCLUSION

Physical activity, sedentary time, and physical fitness were significantly related to the shapes of subcortical brain structures, which in turn were related to intelligence in children with overweight/obesity.

Body Mass Index and Academic Achievement Among Chinese Secondary School Students: The Mediating Effect of Inhibitory Control and the Moderating Effect of Social Support

Based on Embodied Cognition Theory, Inhibitory Decline Theory, and Risk Protective Factors Model, this study verified that body mass index (BMI) affects secondary school students’ academic performance through the mechanism of inhibitory control. In addition, it was verified that the strength of this mechanism depends on the teacher, parent, and peer support received by secondary school students. By using height and weight measurements, the classic stroop task, and the social support scale, 264 secondary school students in Shanxi Province, China, were surveyed and their academic performance was collected. The results showed that students with high BMI had poorer academic performance, and inhibitory control partially mediated the effect between BMI and academic performance, with the inhibitory control mediated effect accounting for 36.68% of the total effect. Support from teachers, parents, and peers can ameliorate the negative effects of BMI on academic performance, with teacher support and parental support also ameliorating the negative effects of BMI on inhibitory control. Thus, high BMI impairs inhibitory control and thus has a negative impact on academic performance, which can be buffered by social support.

Neural correlates of sleep quality in children: Sex-specific associations shown by brain diffusion tractography

BACKGROUND AND PURPOSE

Sleep quality is important for healthy growth and development of children. We aimed to identify associations between sleep disturbances in healthy children without clinical diagnosis of sleep disorders and brain white matter (WM) microstructure using an advanced diffusion-weighted magnetic resonance imaging (DW-MRI) based tractography analysis, and to explore whether there are sex differences in these associations.

METHODS

Brain DW-MRI data were collected from sixty-two 8-year-old children (28 boys, 34 girls) whose parents also completed Children's Sleep Habits Questionnaire (CSHQ). Track-weighted imaging (TWI) measures were computed from the DW-MRI data for 37 WM tracts in each subject. Sex-specific partial correlation analyses were performed to evaluate correlations between TWI measures and a set of sleep disturbance scores derived from the CSHQ.

RESULTS

Significant correlations (P < .05, FDR-corrected; r: .48-.67) were identified in 13 WM tracts between TWI and sleep disturbance scores. Sexually dimorphic differences in correlations between sleep disturbance scores and WM microstructure measurements were observed. Specifically, in boys, daytime sleepiness positively correlated with track-weighted mean or radial diffusivity in 10 WM tracts (bilateral arcuate fasciculus, left cingulum, right middle longitudinal fasciculus, and three bilateral segments of superior longitudinal fasciculus). In girls, total CSHQ score, night walking, or sleep onset delay negatively correlated with track-weighted fractional anisotropy or axial diffusivity in 4 WM tracts (bilateral inferior longitudinal fasciculus and uncinate fasciculus).

CONCLUSIONS

The findings suggest that sleep disturbances without clinical diagnosis of sleep disorders are associated with lower WM microstructural integrity in children. Additionally, the associations possess unique patterns in boys and girls.

Sleep Disturbances, Obesity, and Cognitive Function in Childhood: A Mediation Analysis

BACKGROUND

Childhood cognitive development is influenced by biological and environmental factors. One such factor, obesity, impairs cognitive development and is associated with sleep disturbances.

OBJECTIVES

We aimed to examine the mediating role of sleep disturbances on the relation between BMI and cognitive function in children.

METHODS

A total of 9951 children aged 9-10 y were included in this cross-sectional study. Children were recruited from the longitudinal ABCD (Adolescent Brain Cognitive Development) Study. Cognitive development was assessed using metrics for fluid, crystallized, and total cognitive function. Mediation analyses were conducted via linear regression modeling, with adjustment for potential confounders (sex, age, ethnicity, household income, parental education, and self-reported physical activity) for each of the 3 outcomes. Mediation significance was determined by bootstrapping.

RESULTS

A statistically significant inverse association was found between BMI and total (β = -0.41, P < 0.001) and fluid (β = -0.49, P < 0.001) cognition, but not for crystallized cognition. Total sleep disturbances partially mediated the association between BMI and fluid cognition (indirect effect: -0.02, P = 0.002; proportion of the total effect: 0.05, P = 0.002), but no mediation was found in the association between BMI and total cognition.

CONCLUSIONS

Sleep disturbances partially mediate the effect of childhood obesity on cognitive function, particularly in fluid cognitions. Future work is necessary to understand the effects of sleep disturbances and obesity on reduced childhood cognition throughout time, predominantly across the life course.

Physical Fitness Plays a Crucial Mediator Role in Relationships Among Personal, Social, and Lifestyle Factors With Adolescents' Cognitive Performance in a Structural Equation Model. The Cogni-Action Project

Background: The beneficial relationship between physical fitness and cognitive performance is affected and modulated by a wide diversity of factors that seem to be more sensitive during the development stage, particularly during early adolescence. This study aimed to examine the role of physical fitness considering the multivariate association between age, health-related quality of life (HRQOL), school vulnerability index (SVI), body mass index z-score (BMIz), physical activity, and sleep problems with the cognitive performance in boys and girls. Method: Participants were 1,196 adolescents aged 10-14 years (50.7% of boys) from Chile. Three physical fitness components and eight cognitive tasks were measured. BMIz was determined using growth references by age and sex, whereas questionaries were used to assess sleep problems, physical activity, and HRQOL. SVI was established according to the score given by the Chilean Government to educational establishments. We performed a structural equation model (SEM) to test multivariate associations among study' variables by sex. Results: Fitness was positively associated with boys' and girls' cognitive performance (β = 0.23 and β = 0.17; p = 0.001, respectively). Moreover, fitness presented a significant mediator role in the relationships between BMIz, SVI, and physical activity with cognitive performance (indirect effect). Additionally, SVI showed a negative association both direct and indirect effect in all three fitness components and all cognitive tasks, being this relationship stronger in girls than in boys. Conclusion: Our findings suggest that physical fitness and all its components play a crucial mediator role in the associations between several factors associated with adolescents' cognitive performance. Thereby, educational and health strategies should prioritise improving physical fitness through physical activity. They also should address other factors such as school vulnerability, obesity, and the early gender gap in a comprehensive approach boosting cognitive performance among early adolescents. Trial registration: Research Registry (ID: researchregistry5791).