title: Salivary alpha amylase diurnal pattern and stress response are associated with body mass index in low-income preschool-aged children.
abstract: Physiological stress responses are proposed as a pathway through which stress can "get under the skin" and lead to health problems, specifically obesity. We tested associations of salivary alpha amylase (sAA) diurnal patterns and stress responses with body mass index (BMI) in young, low-income children (51% male; 54% non-Hispanic white). Diurnal saliva samples were collected three times per day across three days for 269 children (M age 50.8 months, SD 6.3). Individual sAA intercept and slope values were calculated using random effect models to represent morning sAA levels and rate of sAA change across the day. A subset of children (n=195; M age 56.6 months, SD 6.9) participated in a lab-based behavioral stress protocol. Area under the curve increase (AUCI) across four timepoints was calculated to represent increase in sAA output during stress elicitation. Children were weighed and height measured and BMI z-score was calculated. Linear regression was used to evaluate associations of sAA intercept, sAA slope, and sAA AUCI with BMI z-score, controlling for child age, sex, and race/ethnicity; maternal weight status; and family income-to-needs ratio. Diurnal and stress-response sAA patterns were related to child adiposity: for each 1-standard deviation unit (SDU) decrease in morning sAA level, the child's BMI z-score increased by 0.11 (SE 0.05) SDU's (p<.04); for each 1-SDU increase in sAA slope across the day, the child's BMI z-score increased by 0.12 (SE 0.05) SDU's (p<.03); and for each 1-SDU decrease in sAA AUCI during the stress elicitation, the child's BMI z-score increased by 0.14 (SE 0.06) SDU's (p<.03). Blunted stress responses and atypical diurnal patterns of sAA have been found following exposure to chronic life stressors such as poverty. Findings suggest that associations of stress, sAA, and elevated body mass index may develop very early in the lifespan.
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States; Department of Health Behavior and Health Education, University of Michigan School of Public Health, United States. Electronic address: alimill@umich.edu.
authors.forename: Alison L
authors.initials: AL
authors.lastname: Miller
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States.
authors.forename: Julie
authors.initials: J
authors.lastname: Sturza
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States; Department of Psychiatry, University of Michigan Medical School, United States.
authors.forename: Katherine
authors.initials: K
authors.lastname: Rosenblum
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States; Department of Psychiatry, University of Michigan Medical School, United States; Department of Pediatrics, University of Michigan Medical School, United States.
authors.forename: Delia M
authors.initials: DM
authors.lastname: Vazquez
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States.
authors.forename: Niko
authors.initials: N
authors.lastname: Kaciroti
authors.affiliation: Center for Human Growth and Development, University of Michigan, United States; Department of Pediatrics, University of Michigan Medical School, United States; Department of Environmental Health Sciences, University of Michigan School of Public Health, United States.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Lumeng
mesh_terms: D015992:Body Mass Index; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009765:Obesity / Q000378:metabolism*; D011203:Poverty; D012463:Saliva / Q000737:chemistry*; D055291:Salivary alpha-Amylases / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D055291:Salivary alpha-Amylases
keywords: Child; Low-income; Obesity; Salivary alpha-amylase (sAA); Stress