The influence of cortisol and stress in the development of obesity and metabolic syndrome has received increased interest in recent years due to the high prevalence of overweight and obesity in children, youth, and adults. Some studies suggest that physical activity may attenuate the relationship between stress and metabolic syndrome, but more studies are necessary to fully understand this relationship. Many studies have shown a relationship between stress and metabolic syndrome using survey measures, but researchers have not linked survey measures to HPA axis activity. Therefore, the purpose of this study was to examine the relationship between stress (using daily cortisol and survey measures) and metabolic syndrome in obese youth, and to examine the potential moderating effects of physical activity on that relationship. METHODS: Obese adolescents were recruited from the Healthy Weight Center (HWC) and Academic General Pediatrics (AGP) clinics at Helen DeVos Children's Hospital in Grand Rapids, MI. Height, weight, waist circumference, blood pressure, and pubertal stage were obtained at the time of a routine clinic visit, and BMI was calculated. Participants completed the Pediatric Symptom Checklist (PSC) to evaluate psychosocial function (stress). Physical activity (steps/day and minutes per day spent in moderate-to-vigorous physical activity - MVPA) was monitored using the SenseWear Pro III armband (SWA). Participants provided saliva samples (while at home on a weekend day) that were taken at prescribed times: 1) immediately upon waking; 2) 30-minutes after waking; 3) 3 hours after waking; 4) 6 hours after waking; 5) 9 hours after waking; 6) 12 hours after waking. Fasting measures of HDL cholesterol, triglycerides, and glucose were obtained from physician-ordered blood draws and used with waist circumference and systolic blood pressure to calculate a continuous metabolic syndrome risk score (cMetS). RESULTS: A total of 50 subjects (15 boys, 35 girls; mean age 14.8 ± 1.9 y) agreed to participate. The mean cMetS score was 4.16 ± 4.30 and did not differ by clinic or sex. Subjects participated in approximately 46 min of moderate-to-vigorous physical activity per day. Mean cAUC was 1.337 ± 0.867 ug/dl (1.180 ± 0.753 ug/dl and 1.408 ± 0.922 ug/dl for males and females, respectively) and did not differ by sex or clinic. No significant relationship was found between cAUC and cMetS (R2=0.113, p=0.66). Additionally, neither the interactions of steps/day nor MVPA with cAUC significantly predicted cMetS. Partial correlations revealed a significant inverse relationship between PSC total score and cAUC (r=-0.45, p=0.04). Significant inverse relationships were also found between cAUC and PSC total score, internalizing score, and externalizing score, as well as between all three PSC scores and cortisol sample 2. Finally, no significant relationship was found between PSC score and cMetS, nor was there a significant moderating effect of steps/day or MVPA on this relationship. DISCUSSION: The results of this study did not support a relationship between either cortisol or PSC scores and MetS in this sample, nor was there evidence of a moderating effect of physical activity. However, more research is necessary, including survey measures that assess specific domains of stress and longitudinal data to identify the timing of altered cortisol release, metabolic effects, and exposure and reactions to stressors.
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