Recent Submissions

  • Exercise effects on depressive symptoms and self-worth in overweight children: a randomized controlled trial

    Petty, Karen H.; Davis, Catherine L.; Tkacz, Joseph; Young-Hyman, Deborah; Waller, Jennifer L; GEORGIA PREVENTION INSTITUTE (Oxford University Press on behalf of the Society of Pediatric Psychology, 2009-10)
    Objective To test the dose–response effects of an exercise program on depressive symptoms and self-worth in children. Method Overweight, sedentary children (N = 207, 7–11 years, 58% male, 59% Black) were randomly assigned to low or high dose (20 or 40 min/day) aerobic exercise programs (13 ± 1.6 weeks), or control group. Children completed the Reynolds Child Depression Scale and Self-Perception Profile for Children at baseline and posttest. Results A dose–response benefit of exercise was detected for depressive symptoms. A race × group interaction showed only White children's global self-worth (GSW) improved. There was some evidence that increased self-worth mediated the effect on depressive symptoms. Conclusions This study shows dose–response benefits of exercise on depressive symptoms and self-worth in children. However, Blacks did not show increased GSW in response to the intervention. Results provide some support for mediation of the effect of exercise on depressive symptoms via self-worth.
  • Utility of waist circumference percentile for risk evaluation in obese children

    Bassali, Reda; Waller, Jennifer L; Gower, Barbara; Allison, Jerry; Davis, Catherine L.; GEORGIA PREVENTION INSTITUTE (Taylor & Francis Online, 2010)
    Objective. Increased waist circumference has been shown to contribute to cardiovascular risk in obese adults. This study was designed to examine whether routinely assessing waist circumference in obese children adds predictive value for the development of diabetes and other cardiovascular risk factors. Methods. This is a cross-sectional study on a community sample of 188 apparently healthy obese children 711 years, 60% black, 39% male. Anthropometry, fasting lipid profile, oral glucose tolerance test, and magnetic resonance imaging of abdominal fat were done. High waist circumference was defined as ≥ 90 th percentile for age and sex. Statistical analyses were done to examine the relationship between waist circumference and the different cardiovascular risk factors. Results. Those with a high waist circumference had significantly lower high-density lipoprotein, higher triglycerides, fasting insulin, insulin response to glucose, subcutaneous and visceral abdominal fat than those with a normal waist circumference. Children with a high waist circumference were 3.6 times more likely than those with a normal waist status to have a low high-density lipoprotein level, 3.0 times more likely to have high triglycerides, and 3.7 times more likely to have a high fasting insulin level. Conclusions. Obese children with waist circumference at or above the 90th percentile are at higher risk for dyslipidemia and insulin resistance than obese children with normal waist circumference. These results indicate that routine waist circumference evaluation in obese children may help clinicians identify which obese children are at greater risk of diabetes and other cardiovascular disease.
  • Aerobic fitness thresholds associated with fifth grade academic achievement

    Wittberg, Richard; Cottrell, Lesley A.; Davis, Catherine L.; Northrup, Karen L.; GEORGIA PREVENTION INSTITUTE (Taylor & Francis Online, 2010)
    Background: Whereas effects of physical fitness and physical activity on cognitive function have been documented, little is known about how they are related. Purpose: This study assessed student aerobic fitness measured by FITNESSGRAM Mile times and/or Pacer circuits and whether the nature of the association between aerobic fitness and standardized academic performance is dose-response or threshold related. Methods: Standardized academic test scores and aerobic capacity scores were collected from two cohorts of 5th grade students over two years. The Mile run and Pacer circuits results were compared to patterns in students’ academic test scores. Results: Sectioning of Mile times and Pacer circuits revealed a sharp peak in academic performance for boys who completed the Mile in 9 minutes or less. Girls’ Pacer revealed peaks in academic performance at 12 and 30 circuits. Discussion: Results demonstrate that select achievements in the Mile or Pacer account for significant increases in academic performance on standardized tests. Translation to Health Education Practice: This study identifies aerobic fitness points which, if achieved, offer the greatest probability of increased academic success in fifth graders. Physical education, cross-curricular thematic units, and club activities can be portals of opportunity to increase moderate to vigorous physical activity and fitness in students. Furthermore, school-based physical activity and fitness opportunities may positively impact health risk factors associated with childhood obesity. Policies that increase aerobic activity opportunities in the school setting may increase overall academic performance, encourage positive health habits and improve immediate and future overall health.
  • Disordered eating behavior in individuals with diabetes: Importance of context, evaluation, and classification

    Young-Hyman, Deborah L.; Davis, Catherine L.; GEORGIA PREVENTION INSTITUTE (American Diabetes Association, 2010-03)
    Limitations of current research findings: Gaps in understanding the association of DEB and diabetes include: lack of weightmatched control subjects when comparing the prevalence of eating disorders or subclinical DEB; evaluation of the contributions of an insulin dosing schedule and overinsulinization (19), loss of satiety mechanisms via hormonal dysregulation, and dietary prescriptions as potential causes perceived as loss of control over food intake; the intent of behavior in those seeking to prevent weight gain secondary to treatment; incomplete psychological characterization of samples, including psychological constructs such as loss of control, autonomy, and selfefficacy over blood glucose and weight; the potential for misclassification of behaviors and attitudes as reflecting DEB when they possibly reflect skills and attitudes learned as part of the diabetes care/self-management regimen; and the need for refinement of existing measurement tools and development of assessment methods that address diabetes-specific attitudes, concerns, and behaviors that are prescribed as part of treatment; as well as physiological mechanisms that are beyond the control of the patient. Most studied cohorts have consisted of subjects that were white, heavier than control samples, recruited from tertiary care centers, and often monitored more frequently and thoroughly than patients receiving care in the community. Sample selection bias may be operating to eliminate well-controlled well-adjusted individuals from clinical studies, potentially selecting individuals most vulnerable to the development of DEB. No studies were identified that monitored patients from the time of diagnosis to establish the temporal sequence of the onset of behavior considered maladaptive and whether weight gain occurs first or the care regimen is manipulated to prevent weight gain. Few studies could be found wherein the comorbidity of depression and other forms of psychological distress and DEB were evaluated. Directions for future research: Evaluation, characterization, and classifi-cation of DEB in individuals with diabetes have clinical importance. However, classification of these behaviors is less clinically informative if population-specific criteria and taxonomy are not established. Further, focusing on identified gaps in future investigations of DEB in this population could improve clinical care for this serious comorbid condition. Studies that chronicle the development of DEB prospectively from diagnosis will allow us to assess the contributions of the many factors that predispose individuals to the development of DEB, potentially identifying approaches to diabetes treatment with a lower risk of iatrogenic complications. It is clinically important to be able to identify those individuals who are at risk for this comorbid condition in association with and independent of the burden of diabetes care. In order to distinguish whether insulin reduction or omission is maladaptive, evaluation of the intent and context of this behavior is needed. Is it a means to regain control over excessive eating by using self-management skills or, in contrast, is it intended as a short-cut weight management strategy (purging via glycosuria)? Physiological mechanisms such as an insulin dose in excess of physiological requirement, hypoglycemia, and a hormonally driven imbalance in hunger, food intake, and experience of satiety appear to be critical factors in establishing diabetes-specific criteria that discriminate between maladaptive manipulations of the diabetes care regimen to control weight and potentially adaptive regimen modifications. Studies are needed that address these distinctions.
  • Undetected hypertension and prehypertension in children with diabetes need attention

    Davis, Catherine L.; GEORGIA PREVENTION INSTITUTE (Elsevier, 2010-06-04)
  • Lower bone mass in prepubertal overweight children with prediabetes

    Pollock, Norman K; Bernard, Paul J.; Wenger, Karl; Misra, Sudipta; Gower, Barbara; Allison, Jerry D.; Zhu, Haidong; Davis, Catherine L.; GEORGIA PREVENTION INSTITUTE (American Society for Bone and Mineral Research, 2010-12)
    Childhood studies of the fat-bone relationship are conflicting, possibly reflecting the influence of metabolic abnormalities in some but not all obese children. Bone mass was compared between prepubertal overweight children with (n=41) and without (n=99) prediabetes. Associations of bone mass with measures of total and central adiposity, glucose intolerance, insulin sensitivity, lipid profile, systemic inflammation, and osteocalcin also were determined. In 140 overweight children aged 7 to 11 years, an oral glucose tolerance test was used to identify those with prediabetes and for determination of glucose, 2-hour glucose, glucose area under the curve (AUC), insulin, 2-hour insulin, and insulin AUC. Blood samples also were assessed for lipids, C-reactive protein, and osteocalcin. Total-body bone mineral content (BMC), fat-free soft tissue mass (FFST), and fat mass (FM) were measured by dual-energy X-ray absorptiometry (DXA). Visceral adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAAT) were assessed using MRI. Total-body BMC was 4% lower in overweight children with prediabetes than in those without prediabetes after controlling for sex, race, height, and weight (p=.03). In the total sample, FM was positively related with BMC (β=0.16, p=.01) after adjusting for sex, race, height, and FFST. However, VAT (β=-0.13, p=.03) and SAAT (β=-0.34, p=.02) were inversely associated with BMC after controlling for sex, race, height, FFST, FM, and SAAT or VAT. No significant associations were found between BMC and the biochemical measurements. Prepubertal overweight children with prediabetes may be at risk for poor skeletal development. In addition, it appears that greater levels of central rather than total adiposity may be deleterious for developing bone.
  • Exercise Improves Executive Function and Achievement and Alters Brain Activation in Overweight Children: A Randomized, Controlled Trial

    Davis, Catherine L.; Tomporowski, Phillip D.; McDowell, Jennifer E.; Austin, Benjamin P.; Miller, Patricia H.; Yanasak, Nathan E.; Allison, Jerry D.; Naglieri, Jack A.; GEORGIA PREVENTION INSTITUTE (APA PsycNet, 2011-01)
    Objective: This experiment tested the hypothesis that exercise would improve executive function. Design: Sedentary, overweight 7- to 11-year-old children (N = 171, 56% girls, 61% Black, M ± SD age = 9.3 ± 1.0 years, body mass index [BMI] = 26 ± 4.6 kg/m 2, BMI z-score = 2.1 ± 0.4) were randomized to 13 ± 1.6 weeks of an exercise program (20 or 40 min/day), or a control condition. Main Outcome Measures: Blinded, standardized psychological evaluations (Cognitive Assessment System and Woodcock-Johnson Tests of Achievement III) assessed cognition and academic achievement. Functional MRI measured brain activity during executive function tasks. Results: Intent to treat analysis revealed dose-response benefits of exercise on executive function and mathematics achievement. Preliminary evidence of increased bilateral prefrontal cortex activity and reduced bilateral posterior parietal cortex activity attributable to exercise was also observed. Conclusion: Consistent with results obtained in older adults, a specific improvement on executive function and brain activation changes attributable to exercise were observed. The cognitive and achievement results add evidence of dose-response and extend experimental evidence into childhood. This study provides information on an educational outcome. Besides its importance for maintaining weight and reducing health risks during a childhood obesity epidemic, physical activity may prove to be a simple, important method of enhancing aspects of children's mental functioning that are central to cognitive development. This information may persuade educators to implement vigorous physical activity.
  • Leukocyte telomere length in healthy caucasian and african-american adolescents: Relationships with race, sex, adiposity, adipokines, and physical activity

    Zhu, Haidong; Wang, Xiaoling; Gutin, Bernard; Davis, Catherine L.; Keeton, Daniel; Thomas, Jeffrey; Stallmann-Jorgensen, Inger; Mooken, Grace; Bundy, Vanessa; Snieder, Harold; et al. (Elsevier, 2011-02)
    Objective: To examine the relationships of race, sex, adiposity, adipokines, and physical activity to telomere length in adolescents. Study design: Leukocyte telomere length (T/S ratio) was assessed cross-sectionally in 667 adolescents (aged 14-18 years; 48% African-Americans; 51% girls) using a quantitative polymerase chain reaction method. Generalized estimating equations analyses were performed. Results: Telomere length was greater in the African-American adolescents than in the Caucasian adolescents (age- and sex-adjusted T/S ratio ± SE, 1.32 ± 0.01 vs 1.27 ± 0.01: P = .014) and greater in girls than in boys (age- and race-adjusted T/S ratio ± SE, 1.31 ± 0.01 vs 1.27 ± 0.01; P = .007). None of the adiposity or adipokine measures explained a significant proportion of the variance in telomere length. Vigorous physical activity was positively associated with telomere length (adjusted R2 = 0.019; P = .009) and accounted for 1.9% of the total variance only in girls. Conclusions: This study, conducted in a biracial adolescent cohort, demonstrated that (1) race and sex differences in telomere length have already emerged during adolescence; (2) adiposity and adipokines are not associated with telomere length at this age; and (3) the antiaging effect of vigorous physical activity may begin in youth, especially in girls.
  • Adolescent obesity, bone mass, and cardiometabolic risk factors

    Pollock, Norman K.; Bernard, Paul J.; Gutin, Bernard; Davis, Catherine L.; Zhu, Haidong; Dong, Yanbin; GEORGIA PREVENTION INSTITUTE (Elsevier, 2011-05)
    Objective: To compare bone mass between overweight adolescents with and without cardiometabolic risk factors (CMR). Associations of bone mass with CMR and adiposity were also determined. Study design: Adolescents (aged 14 to 18 years) who were overweight were classified as healthy (n = 55), having one CMR (1CMR; n = 46), or having two or more CMR (≥2CMR; n = 42). CMRs were measured with standard methods and defined according to pediatric definitions of metabolic syndrome. Total body bone mass, fat mass, and fat-free soft tissue mass were measured with dual-energy X-ray absorptiometry. Visceral adipose tissue and subcutaneous abdominal adipose tissue were assessed with magnetic resonance imaging. Results: After controlling for age, sex, race, height, and fat-free soft tissue mass, the healthy group had 5.4% and 6.3% greater bone mass than the 1CMR and ≥2CMR groups, respectively (both P values <.04). With multiple linear regression, adjusting for the same co-variates, visceral adipose tissue (β = -0.22), waist circumference (β = -0.23), homeostasis model assessment of insulin resistance (β = -0.23), and high-density lipoprotein cholesterol level (β = 0.22) were revealed to be associated with bone mass (all P values <.04). There was a trend toward a significant inverse association between bone mass and fasting glucose level (P = .056). No relations were found between bone mass and fat mass, subcutaneous abdominal adipose tissue, blood pressure, or triglyceride level. Conclusion: Being overweight with metabolic abnormalities, particularly insulin resistance, low high-density lipoprotein cholesterol level, and visceral adiposity, may adversely influence adolescent bone mass.
  • Fitness, fatness, cognition, behavior, and academic achievement among overweight children: Do cross-sectional associations correspond to exercise trial outcomes?

    Davis, Catherine L.; Cooper, Stephanie; GEORGIA PREVENTION INSTITUTE (Elsevier, 2011-06-01)
    This study examined associations of fitness and fatness with cognitive processes, academic achievement, and behavior, independent of demographic factors, at the baseline of an exercise trial. Methods: Overweight, sedentary but otherwise healthy 7-11. year olds (N = 170) participated in a study of health, cognition and achievement in the Augusta, GA area from 2003-2006. Children underwent evaluations of fatness and fitness, psychological assessments of cognition and academic achievement, and behavior ratings by parents and teachers. Partial correlations examined associations of fitness and fatness with cognitive and achievement scores and behavior ratings, controlling for demographic factors. Results: Fitness was associated with better cognition, achievement and behavior, and fatness with worse scores. Specifically, executive function, mathematics and reading achievement, and parent ratings of child behavior were related to fitness and fatness. Teacher ratings were related to fitness. Conclusion: These results extend prior studies by providing reliable, standardized measures of cognitive processes, achievement, and behavior in relation to detailed measures of fitness and fatness. However, cross-sectional associations do not necessarily indicate that improving one factor, such as fatness or fitness, will result in improvements in factors that were associated with it. Thus, randomized clinical trials are necessary to determine the effects of interventions.
  • Lower Uncarboxylated Osteocalcin Concentrations in Children with Prediabetes Is Associated with β-Cell Functio

    Pollock, Norman K.; Bernard, Paul J.; Gower, Barbara A.; Gundberg, Caren M.; Wenger, Karl; Misra, Sudipta; Bassali, Reda W.; GEORGIA PREVENTION INSTITUTE (Oxford Academic, 2011-07-01)
    Context: Although animal studies suggest that it is the uncarboxylated rather than carboxylated form of osteocalcin that affects glucose homeostasis, the human data are scant and equivocal. Objective: This study investigated associations of uncarboxylated and carboxylated forms of osteocalcin with insulin sensitivity and β-cell function in 140 overweight prepubertal children (43% female, 46% black, 84% obese) with normal glucose levels (n = 99) and prediabetes (n = 41). Methods: An oral glucose tolerance test was used to identify prediabetes and for measurement of insulin sensitivity (Matsuda index), β-cell function [oral glucose tolerance test derived insulinogenic index and disposition index (DIOGTT)] and uncarboxylated and carboxylated forms of osteocalcin. Visceral adipose tissue (VAT) was assessed using magnetic resonance imaging. Results: After controlling for age, sex and race, lower uncarboxylated osteocalcin concentrations, Matsuda index, insulinogenic index, and DIOGTT and higher VAT levels were found in the prediabetes vs. normal-glucose group (all P < 0.03). Carboxylated osteocalcin levels were not different between groups. Multiple linear regression adjusting for age, sex, race, and VAT revealed that uncarboxylated osteocalcin was associated with insulinogenic index and DIOGTT (β = 0.34, 0.36, respectively, both P < 0.04) in the prediabetes group but not the normal-glucose group. In both the normal-glucose and prediabetes groups, carboxylated osteocalcin was associated with insulin sensitivity (β = 0.26, 0.47, respectively, both P < 0.02). Conclusions: These data suggest that the lower uncarboxylated osteocalcin concentrations found in children with prediabetes may be associated with β-cell dysfunction. In addition, our findings between carboxylated osteocalcin and insulin sensitivity suggest that carboxylated osteocalcin plays a role in human glucose homeostasis.
  • Greater fructose consumption is associated with cardiometabolic riskmarkers and visceral adiposity in adolescents

    Pollock, Norman K; Bundy, Vanessa; Kanto, William; Davis, Catherine L.; Bernard, Paul J.; Zhu, Haidong; Gutin, Bernard; Dong, Yanbin; GEORGIA PREVENTION INSTITUTE (Elsevier, 2012-02-01)
    Though adolescents consume more fructose than any other age group, the relationship between fructose consumption and markers of cardiometabolic risk has not been established in this population. We determined associations of total fructose intake (free fructose plus one-half the intake of free sucrose) with cardiometabolic risk factors and type of adiposity in 559 adolescents aged 14-18 y. Fasting blood samples were measured for glucose, insulin, lipids, adiponectin, and C-reactive protein. Diet was assessed with 4-7 24-h recalls and physical activity (PA) was determined by accelerometry. Fat-free soft tissue (FFST) mass and fat mass were measured by DXA. The s.c. abdominal adipose tissue (SAAT) and visceral adipose tissue (VAT) were assessed using MRI. Multiple linear regression, adjusting for age, sex, race, Tanner stage, FFST mass, fat mass, PA, energy intake, fiber intake, and socioeconomic status, revealed that fructose intake was associated with VAT (β = 0.13; P = 0.03) but not SAAT (P = 0.15). Significant linear upward trends across tertiles of fructose intake were observed for systolic blood pressure, fasting glucose, HOMA-IR, and C-reactive protein after adjusting for the same covariates (all P-trend < 0.04). Conversely, significant linear downward trends across tertiles of fructose intake were observed for plasma HDL-cholesterol and adiponectin (both P-trend < 0.03). When SAAT was added as a covariate, these trends persisted (all P-trend < 0.05). However, when VAT was included as a covariate, it attenuated these trends (all P-trend < 0.05). In adolescents, higher fructose consumption is associated with multiple markers of cardiometabolic risk, but it appears that these relationships are mediated by visceral obesity.
  • A Test of Learned Industriousness in the Physical Activity Domain

    Bustamante, Eduardo E.; Davis, Catherine L.; Marquez, David X.; Augusta University (PMC PubMed Central, 2014-11-10)
    The Theory of Learned Industriousness states that durable individual differences in industriousness are due in part to differences in the extent to which individuals were rewarded for high effort at an earlier time. Individuals rewarded for high effort during training are thought to generalize greater persistence to subsequent tasks than those rewarded for low effort. This study tested whether rewarded physical and/or mental effort at different intensities generalized to greater persistence at a subsequent mental task.
  • Exercise dose and diabetes risk in overweight and obese children: A randomized controlled trial

    Davis, Catherine L.; Pollock, Norman K.; Waller, Jennifer L.; Allison, Jerry David; Dennis, B. Adam; Bassali, Reda; Meléndez, Agustín; Boyle, Colleen A.; Gower, Barbara A.; Augusta University (2012-09-12)
    Context: Pediatric studies have shown that aerobic exercise reduces metabolic risk, but dose-response information is not available. Objectives: To test the effect of different doses of aerobic training on insulin resistance, fatness, visceral fat, and fitness in overweight, sedentary children and to test moderation by sex and race. Design, Setting, and Participants: Randomized controlled efficacy trial conducted from 2003 through 2007 in which 222 overweight or obese sedentary children (mean age, 9.4 years; 42% male; 58% black) were recruited from 15 public schools in the Augusta, Georgia, area. Intervention: Children were randomly assigned to low-dose (20 min/d; n=71) or high-dose (40 min/d; n=73) aerobic training (5 d/wk; mean duration, 13 [SD, 1.6] weeks) or a control condition (usual physical activity; n=78). Main Outcome Measures: The prespecified primary outcomes were postintervention type 2 diabetes risk assessed by insulin area under the curve (AUC) from an oral glucose tolerance test, aerobic fitness (peak oxygen consumption [V̇O 2]), percent body fat via dual-energy x-ray absorptiometry, and visceral fat via magnetic resonance, analyzed by intention to treat. Results: The study had 94% retention (n=209). Most children (85%) were obese. At baseline, mean body mass index was 26 (SD, 4.4). Reductions in insulin AUC were larger in the high-dose group (adjusted mean difference, -3.56 [95% CI, -6.26 to -0.85] ×103 μU/mL; P=.01) and the low-dose group (adjusted mean difference, -2.96 [95% CI, -5.69 to -0.22] ×103 μU/mL; P=.03) than the control group. Dose-response trends were also observed for body fat (adjusted mean difference, -1.4% [95% CI, -2.2% to -0.7%]; P<.001 and -0.8% [95% CI, -1.6% to -0.07%]; P=.03) and visceral fat (adjusted mean difference, -3.9 cm3 [95% CI, -6.0 to -1.7 cm3]; P<.001 and -2.8 cm3 [95% CI, -4.9 to -0.6 cm3]; P=.01) in the high- and low-dose vs control groups, respectively. Effects in the high- and low-dose groups vs control were similar for fitness (adjusted mean difference in peak V̇O2, 2.4 [95% CI, 0.4-4.5] mL/kg/min; P=.02 and 2.4 [95% CI, 0.3-4.5] mL/kg/min; P=.03, respectively). High- vs low-dose group effects were similar for these outcomes. There was no moderation by sex or race. Conclusion: In this trial, after 13 weeks, 20 or 40 min/d of aerobic training improved fitness and demonstrated dose-response benefits for insulin resistance and general and visceral adiposity in sedentary overweight or obese children, regardless of sex or race. Trial Registration Identifier: NCT00108901.
  • Exercise for overweight children and diabetes risk - Reply

    Davis, Catherine L.; Waller, Jennifer L.; Pollock, Norman K.; Augusta University (2013-01-09)
  • Oxidative stress and cardiovascular risk in overweight children in an exercise intervention program

    Dennis, B. Adam; Ergul, Adviye; Gower, Barbara A.; Allison, Jerry David; Davis, Catherine L.; Augusta University (2013-02-01)
    Background: This study aimed to determine whether oxidative stress was related to cardiovascular risk indices in children, and whether an exercise intervention would reduce oxidative stress. Methods: A randomized trial of two different doses of exercise and a no-exercise control group included 112 overweight and obese children, 7-11 years old. Plasma isoprostane levels were obtained at baseline and after the intervention. Cross-sectional analysis of oxidative stress and metabolic markers at baseline was performed. The effect of the exercise training on oxidative stress was tested. Results: Lower isoprostane levels were observed in blacks. At baseline, isoprostane was positively related to measures of fatness (BMI, waist circumference, percent body fat), insulin resistance and β-cell function (fasting insulin, insulin area under the curve, Matsuda index, disposition index, oral disposition index), and several lipid markers (low-density lipoprotein, triglycerides, total cholesterol), and inversely with fitness [peak oxygen consumption (VO2)], independent of race, sex, and cohort. No relation was found with visceral fat, blood pressure, or glycemia. Independent of percent body fat, isoprostane predicted triglycerides, β=0.23, total cholesterol-to-high-density lipoprotein (TC/HDL) ratio, β=0.23, and insulin resistance (insulin area under the curve, β=0.24, Matsuda index, β=-0.21, oral disposition index, β=0.33). Exercise did not reduce oxidative stress levels, despite reduced fatness and improved fitness in these children. Conclusions: Isoprostane levels were related to several markers of cardiovascular risk at baseline; however, despite reduced fatness and improved fitness, no effect of exercise was observed on isoprostane levels. To our knowledge, this is the first report in children to demonstrate a correlation of oxidative stress with disposition index, fitness, and TC/HDL ratio, the first to test the effect on oxidative stress of an exercise intervention that reduced body fat, and the first such exercise intervention study to include a substantial proportion of black children.
  • An 8-month randomized controlled exercise trial alters brain activation during cognitive tasks in overweight children

    Krafft, Cynthia E.; Schwarz, Nicolette F.; Chi, Lingxi; Weinberger, Abby L.; Schaeffer, David J.; Pierce, Jordan E.; Rodrigue, Amanda L.; Yanasak, Nathan Eugene; Miller, Patricia H.; Tomporowski, Phillip D.; et al. (2014-01)
    Objective Children who are less fit reportedly have lower performance on tests of cognitive control and differences in brain function. This study examined the effect of an exercise intervention on brain function during two cognitive control tasks in overweight children. Design and Methods Participants included 43 unfit, overweight (BMI ≥ 85th percentile) children 8- to 11-years old (91% Black), who were randomly divided into either an aerobic exercise (n = 24) or attention control group (n = 19). Each group was offered a separate instructor-led after-school program every school day for 8 months. Before and after the program, all children performed two cognitive control tasks during functional magnetic resonance imaging (fMRI): antisaccade and flanker. Results Compared to the control group, the exercise group decreased activation in several regions supporting antisaccade performance, including precentral gyrus and posterior parietal cortex, and increased activation in several regions supporting flanker performance, including anterior cingulate and superior frontal gyrus. Conclusions Exercise may differentially impact these two task conditions, or the paradigms in which cognitive control tasks were presented may be sensitive to distinct types of brain activation that show different effects of exercise. In sum, exercise appears to alter efficiency or flexible modulation of neural circuitry supporting cognitive control in overweight children.
  • An eight month randomized controlled exercise intervention alters resting state synchrony in overweight children

    Krafft, Cynthia E.; Pierce, Jordan E.; Schwarz, Nicolette F.; Chi, Lingxi; Weinberger, Abby L.; Schaeffer, David J.; Rodrigue, Amanda L.; Canchong, J.; Allison, Jerry David; Yanasak, Nathan Eugene; et al. (2014-01-03)
    Children with low aerobic fitness have altered brain function compared to higher-fit children. This study examined the effect of an 8-month exercise intervention on resting state synchrony. Twenty-two sedentary, overweight (body mass index ≥85th percentile) children 8-11. years old were randomly assigned to one of two after-school programs: aerobic exercise (n= 13) or sedentary attention control (n= 9). Before and after the 8-month programs, all subjects participated in resting state functional magnetic resonance imaging scans. Independent components analysis identified several networks, with four chosen for between-group analysis: salience, default mode, cognitive control, and motor networks. The default mode, cognitive control, and motor networks showed more spatial refinement over time in the exercise group compared to controls. The motor network showed increased synchrony in the exercise group with the right medial frontal gyrus compared to controls. Exercise behavior may enhance brain development in children.
  • Improved frontoparietal white matter integrity in overweight children is associated with attendance at an after-school exercise program

    Krafft, Cynthia E.; Schaeffer, David J.; Schwarz, Nicolette F.; Chi, Lingxi; Weinberger, Abby L.; Pierce, Jordan E.; Rodrigue, Amanda L.; Allison, Jerry David; Yanasak, Nathan Eugene; Liu, Tianming; et al. (2014-03)
    Aerobic fitness is associated with white matter integrity (WMI) in adults as measured by diffusion tensor imaging (DTI). This study examined the effect of an 8-month exercise intervention on WMI in children. Participants were 18 sedentary, overweight (BMI ≥85th percentile) 8- to 11-year-old children (94% Black), randomly assigned to either an aerobic exercise (n = 10) or sedentary attention control group (n = 8). Each group was offered an instructor-led after-school program every school day for approximately 8 months. Before and after the program, all subjects participated in DTI scans. Tractography was conducted to isolate the superior longitudinal fasciculus and investigate whether the exercise intervention affected WMI in this region. There was no group by time interaction for WMI in the superior longitudinal fasciculus. There was a group by time by attendance interaction, however, such that higher attendance at the exercise intervention, but not the control intervention, was associated with increased WMI. Heart rate and the total dose of exercise correlated with WMI changes in the exercise group. In the overall sample, increased WMI was associated with improved scores on a measure of attention and improved teacher ratings of executive function. This study indicates that participating in an exercise intervention improves WMI in children as compared to a sedentary after-school program.
  • Obesity elicits interleukin 1-mediated deficits in hippocampal synaptic plasticity

    Erion, Joanna R.; Wosiski-Kuhn, Marlena; Dey, Aditi; Hao, Shuai; Davis, Catherine L.; Pollock, Norman K.; Stranahan, Alexis M.; Augusta University (2014)
    Adipose tissue is a known source of proinflammatory cytokines in obese humans and animal models, including the db/db mouse, in which obesity arises as a result of leptin receptor insensitivity. Inflammatory cytokines induce cognitive deficits across numerous conditions, but no studies have determined whether obesity-induced inflammation mediates synaptic dysfunction. To address this question, we used a treadmill training paradigm in which mice were exposed to daily training sessions or an immobile belt, with motivation achieved by delivery of compressed air on noncompliance. Treadmill training prevented hippocampal microgliosis, abolished expression of microglial activation markers, and also blocked the functional sensitization observed in isolated cells after ex vivo exposure to lipopolysaccharide. Reduced microglial reactivity with exercise was associated with reinstatement of hippocampus-dependent memory, reversal of deficits in long-term potentiation, and normalization of hippocampal dendritic spine density. Because treadmill training evokes broad responses not limited to the immune system, we next assessed whether directly manipulating adiposity through lipectomy and fat transplantation influences inflammation, cognition, and synaptic plasticity. Lipectomy prevents and fat transplantation promotes systemic and central inflammation, with associated alterations in cognitive and synaptic function. Levels of interleukin 1β (IL1β) emerged as a correlate of adiposity and cognitive impairment across both the treadmill and lipectomy studies, so we manipulated hippocampal IL1 signaling using intrahippocampal delivery of IL1 receptor antagonist (IL1ra). Intrahippocampal IL1ra prevented synaptic dysfunction, proinflammatory priming, and cognitive impairment. This pattern supports a central role for IL1-mediated neuroinflammation as a mechanism for cognitive deficits in obesity and diabetes.

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