Denise M. Feda

Food Reinforcement and Parental Obesity Predict Future Weight Gain in Non-Obese Adolescents

BACKGROUND Food reinforcement, the extent to which people are willing to work to earn a preferred snack food, and parental obesity are risk factors for weight gain, but there is no research comparing the predictive effects of these factors for adolescent weight gain. METHODS 130 non-obese adolescents (M age=15.2 ± 1.0; M BMI=20.7 ± 2.0; M zBMI=0.16 ± 0.64) at differential risk for weight gain based on parental obesity completed baseline food and money reinforcement tasks, and provided zBMI data over a 2-year follow-up. RESULTS The number of obese (BMI ≥ 30) parents (p=0.007) and high food reinforcement (p=0.046) were both significant independent predictors of greater zBMI increases, controlling for age, sex, parent education and minority status. Having no obese parents or being low or average in food reinforcement was associated with reductions in zBMI, but those high in food reinforcement showed larger zBMI increases (0.102) than having one obese parent (0.025) but less than having two obese parents (0.177). DISCUSSION Food reinforcement and parental obesity independently predict future weight gain among adolescents. It might be fruitful for obesity prevention programs to target both high risk groups.

Stress-induced cardiovascular reactivity and atherogenesis in adolescents

OBJECTIVE To examine the association between cardiovascular reactivity to a set of psychological stressors and carotid artery intima-media thickness, a marker of subclinical cardiovascular disease in healthy adolescents. METHODS Participants were 25 boys and 23 girls age 14.2 ± 0.9 years who were measured for heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure reactivity to mirror-tracing, reaction time, speech preparation and ad lib speech tasks and for common carotid artery intima-media thickness. Sequential regression analyses were used to establish the incremental increase in R(2)(R(inc)(2)) for the prediction of intima-media thickness due to cardiovascular reactivity independent of age, BMI percentile, sex, socioeconomic status, and resting HR or BP. RESULTS SBP reactivity while preparing (β=0.0019, R(inc)(2)=0.09) and giving the speech (β=0.0014, R(inc)(2)=0.10) and an aggregate reactivity score based on all 4 tasks (β=0.0026, R(inc)(2)=0.11) independently predicted (p ≤ 0.05) mean carotid artery intima-media thickness. Neither DBP reactivity nor HR reactivity during any task were independent predictors of intima-media thickness. CONCLUSION Stress-induced cardiovascular reactivity, and especially SBP reactivity, is associated with carotid intima-media thickness and the early pathogenesis of cardiovascular disease. The use of an aggregate stress reactivity index provides a more reliable reflection of trait SBP reactivity to psychological stress and increases the confidence that youth with greater cardiovascular stress reactivity may indeed have greater progression of subclinical cardiovascular disease.

Origins of food reinforcement in infants

BACKGROUND Rapid weight gain in infancy is associated with a higher risk of obesity in children and adults. A high relative reinforcing value of food is cross-sectionally related to obesity; lean children find nonfood alternatives more reinforcing than do overweight/obese children. However, to our knowledge, there is no research on how and when food reinforcement develops. OBJECTIVE This study was designed to assess whether the reinforcing value of food and nonfood alternatives could be tested in 9- to 18-mo-old infants and whether the reinforcing value of food and nonfood alternatives is differentially related to infant weight status. DESIGN Reinforcing values were assessed by using absolute progressive ratio schedules of reinforcement, with presentation of food and nonfood alternatives counterbalanced in 2 separate studies. Two nonfood reinforcers [Baby Einstein-Baby MacDonald shows (study 1, n = 27) or bubbles (study 2, n = 30)] were tested against the babys favorite food. Food reinforcing ratio (FRR) was quantified by measuring the reinforcing value of food (Food Pmax) in proportion to the total reinforcing value of food and a nonfood alternative (DVD Pmax or BUB Pmax). RESULTS Greater weight-for-length z score was associated with a greater FRR of a favorite food in study 1 (FRR-DVD) (r = 0.60, P < 0.001) and FRR of a favorite food in study 2 (FRR-BUB) (r = 0.49, P = 0.006), primarily because of the strong association between greater weight-for-length z score and lower DVD Pmax (r = -0.71, P < 0.0001) and BUB Pmax (r = -0.53, P = 0.003). Infant monthly weight gain was positively associated with FRR-DVD (r = 0.57, P = 0.009) and FRR-BUB (r = 0.37, P = 0.047). CONCLUSIONS Our newly developed paradigm, which tested 2 different nonfood alternatives, demonstrated that lean infants find nonfood alternatives more reinforcing than do overweight/obese infants. This observation suggests that strengthening the alternative reinforcers may have a protective effect against childhood obesity.

Stress, behavior, and biology: risk factors for cardiovascular diseases in youth.

Psychological stress reactivity is associated with atherogenesis in youth. The novel hypothesis is that stress promotes atherogenic behaviors, including snacking on energy-dense food and reducing physical activity, and increases adiposity. Stress also increases systolic blood pressure cardiovascular reactivity, which also may be atherogenic. Exercise dampens stress reactivity and may be one mechanism by which it protects against the development of cardiovascular diseases.

Food reinforcement and delay discounting in zBMI-discordant siblings

OBJECTIVE The interaction of food reinforcement and the inability to delay gratification are related to adult energy intake and obesity. This study was designed to test the association of sibling pair differences in relative reinforcing efficacy of food and delay discounting on sibling pair differences in zBMI scores of same-gender zBMI-discordant siblings. DESIGN AND METHODS We tested main and interactive relationships between delay discounting and relative reinforcing efficacy of food on zBMI discordance in 14 zBMI-discordant biological sibling pairs (6 female pairs) using a discordant sibling study design. RESULTS Sibling pair differences in relative reinforcing efficacy of food were associated with sibling pair differences in zBMI (p= 0.046); this effect was moderated by delay discounting (p <0.002). Sibling pairs with greater differences in relative reinforcing efficacy and delay discounting had greater differences in zBMI. CONCLUSIONS The combination of greater sibling pair differences in delay discounting and relative reinforcing efficacy is associated with greater discordance in zBMI in adolescent sibling pairs.

Reducing relative food reinforcement in infants by an enriched music experience.

The reinforcing value of food may be established early in life. Research shows that infant weight status is related to the relative reinforcing value of food versus non‐food alternatives (food reinforcing ratio, FRR). The purpose of this pilot study was to assess the effects of a 6‐week music enhancement program (Music Together®, n = 14) versus an active play date control group (n = 13) on the FRR in 9‐ to 16‐month‐old infants who were high in relative food reinforcement.

Written violence policies and risk of physical assault against Minnesota educators.

Few research studies on school violence policies use quantitative methods to evaluate the impact of policies on workplace violence. This study analyzed nine different written violence policies and their impact on work-related physical assault in educational settings. Data were from the Minnesota Educators’ Study. This large, nested case control study included cases (n=372) who reported physical assaults within the last year, and controls (n=1116) who did not. Multivariate logistic regression analyses, using directed acyclic graphs, estimated risk of assault. Results of the adjusted multivariate model suggested decreased risks of physical assault were associated with the presence of policies regarding how to report sexual harassment, verbal abuse, and threat (OR 0.53; 95 per cent CI: 0.30–0.95); assurance of confidential reporting of events (OR 0.67; 95 per cent CI: 0.44–1.04); and zero tolerance for violence (OR 0.70; 95 per cent CI: 0.47–1.04).

Risk of physical assault against school educators with histories of occupational and other violence: a case-control study.

A case-control study design was used to investigate risks of work-related physical assault (PA) associated with a history of violent victimization among educators. A total of 6,469 state-licensed educators (Kindergarten - Grade 12) worked in the previous 12~months and were eligible to participate. Exposure data were collected from cases (reporting a PA event in previous 12 months, n=290) for the month before PA, and from controls (no work-related PA in previous 12 months; n=867) for a randomly selected working month. Odds ratios and 95% confidence intervals identified increased risks for educators with any prior history of work-related (17.3, 11.4-26.3) or non-work-related PA (2.0, 1.2-3.5). In addition, PA risk in the previous twelve months increased with the number of previous victimizations, and risk also increased for educators with histories of non-physical violence (work- and non work-related). The results present a compelling case for targeted interventions and further research.

The Effect of Increasing Autonomy Through Choice on Young Children’s Physical Activity Behavior

BACKGROUND Increasing autonomy by manipulating the choice of available physical activity options in a laboratory setting can increase physical activity in older children and adults. However, the effect of manipulating the number of physically active choices has yet to be examined in young children in a gymnasium environment. METHODS Twenty children (n = 10 girls, 6.1 ± 1.4 years old) individually participated in 2 [low choice (LC), high choice (HC)] free-choice activity conditions for 30 minutes in a 4360 square foot gymnasium. Children had access to 2 or 8 physical activity options in the LC and HC conditions, respectively. Physical activity behavior was measured via accelerometry. RESULTS Childrens 30-minute accelerometer counts increased (P < .03) from the LC (2675 ± 294 counts·min-1) to the HC (3224 ± 280 counts·min-1) condition. CONCLUSIONS Providing greater autonomy through choice of a greater number of physically active options increased young childrens physical activity participation by 20.5%.

Habituation to a stressor predicts adolescents' adiposity.

ABSTRACT Background and Objectives: Stress is associated with gains in adiposity. One factor that determines how much stress is experienced is how quickly an adolescent reduces responding (habituates) across repeated stressors. The purpose of this study was to determine the association of body mass index (BMI) percentile and the rate of habituation to a stressor. Design: Thirty-four adolescents completed anthropometric measures and a habituation protocol using a within study design. Methods: The habituation protocol measured the rate of decline in perceived stress and heart rate (HR) across four, two-minute serial subtraction trials. Results: Multivariate linear regression revealed the habituation rate of the HR predicted BMI percentile after adjusting for gender, socioeconomic status, and initial HR (β = 17.2, p < .04). Conclusions: Slower habituation to a laboratory stressor was associated with greater BMI percentiles in adolescents.