Pathways of Association from Stress to Obesity in Early Childhood

Obesity Risk Among Young Australian Women: A Prospective Latent Class Analysis

OBJECTIVE

Prospective studies on obesity incidence specifically among young adults have not been reported. This study examined risks of obesity incidence over 19 years among young women without obesity at baseline.

METHODS

Women aged 18 to 23 years at baseline (N = 8,177) were followed up every 2 to 3 years to ages 37 to 42 using the Australian Longitudinal Study on Women's Health. A latent class analysis identified obesity-risk classes based on time-dependent measures of income, education, physical activity, sleep quality, dietary behavior, depression, stressful events, and social functioning. Cox proportional hazards regression models examined associations between incident obesity and latent classes, controlling for covariates.

RESULTS

Four latent classes were identified, including a lower-risk referent class and classes characterized by poor exercise and diet, stress and low income, and multiple intermediate-level risks. Compared with the referent, all three risk classes had significantly higher obesity risk, with the highest risk in the stress and low-income group (hazard ratio = 2.22; 95% CI: 1.92-2.56). Individual risks associated with obesity included lower education, stressful life events, and lower vigorous physical activity.

CONCLUSIONS

Young women without baseline obesity were at risk of developing obesity when they experienced co-occurring behavioral, socioeconomic, and psychosocial risks. Both latent classes and individual risk indicators offer insights into prevention strategies.

Development of the DAGIS intervention study: a preschool-based family-involving study promoting preschoolers' energy balance-related behaviours and self-regulation skills

Background

Preschoolers’ energy balance-related behaviours (EBRBs) and self-regulation skills are important for their later health. Few preschool-based interventions aiming to promote preschoolers’ EBRBs and self-regulation skills, simultaneously reducing differences in EBRBs, due to children’s socio-economic status (SES) background, have been conducted. This study will present the Increased Health and Wellbeing in Preschools (DAGIS) intervention development process applying the Intervention Mapping (IM) framework.

Methods

The development of the DAGIS intervention study, a preschool level clustered randomized controlled trial (RCT), was based on the IM framework. The protocol in IM guides the development process of an intervention through six steps: needs assessment and logic model of the problem, programme outcomes and objectives, design of the programme, production, implementation plan, and evaluation plan.

Results

The needs assessment, part of the step 1 in IM, yielded the base for the DAGIS logic model of change. The model includes objectives related to changes in children’s EBRBs, self-regulation skills, and in psychosocial and physical environment that is determined by parents and early educators. A 22-week programme was developed, and materials for preschools and families were produced. A feasibility study of the recruitment processes, acceptability of the materials and methods, and implementation was conducted. The DAGIS intervention study was conducted September 2017–May 2018 as a clustered RCT including a comprehensive effectiveness and process evaluation. The process evaluation was run throughout the intervention targeting preschools and families.

Conclusion

A preschool-based family-involving programme was developed in the DAGIS intervention study by applying the IM protocol. It was a time- and resource-consuming process. However, the systematic planning, development, and running of the programme have reinforced a comprehensive evaluation, which is a strength in the intervention. The results from the evaluation will enhance the knowledge of how to promote EBRBs and self-regulation skills among preschoolers, and diminish SES differences in them.

Trial registration

ISRCTN57165350 (Prospectively registered January the 8th, 2015).

Biological underpinnings from psychosocial stress towards appetite and obesity during youth: research implications towards metagenomics, epigenomics and metabolomics

Psychosocial stress, uncontrolled eating and obesity are three interrelated epidemiological phenomena already present during youth. This broad narrative conceptual review summarises main biological underpinnings of the stress-diet-obesity pathway and how new techniques can further knowledge. Cortisol seems the main biological factor from stress towards central adiposity; and diet, physical activity and sleep are the main behavioural pathways. Within stress-diet, the concepts of comfort food and emotional eating are highlighted, as cortisol affects reward pathways and appetite brain centres with a role for insulin, leptin, neuropeptide Y (NPY), endocannabinoids, orexin and gastrointestinal hormones. More recently researched biological underpinnings are microbiota, epigenetic modifications and metabolites. First, the gut microbiota reaches the stress-regulating and appetite-regulating brain centres via the gut-brain axis. Second, epigenetic analyses are recommended as diet, obesity, stress and gut microbiota can change gene expression which then affects appetite, energy homeostasis and stress reactivity. Finally, metabolomics would be a good technique to disentangle stress-diet-obesity interactions as multiple biological pathways are involved. Saliva might be an ideal biological matrix as it allows metagenomic (oral microbiota), epigenomic and metabolomic analyses. In conclusion, stress and diet/obesity research should be combined in interdisciplinary collaborations with implementation of several -omics analyses.

Sex Dimorphic Responses of the Hypothalamus-Pituitary-Thyroid Axis to Maternal Separation and Palatable Diet

Neonatal stress contributes to the development of obesity and has long-lasting effects on elements of the hypothalamus-pituitary-thyroid (HPT) axis. Given the importance of thyroid hormones in metabolic regulation, we studied the effects of maternal separation and a high-fat/high-carbohydrate diet (HFC), offered from puberty or adulthood, on HPT axis activity of adult male and female Wistar rats. Pups were non-handled (NH) or maternally separated (MS) 3 h/day at postnatal days (Pd) 2-21. In a first experiment, at Pd60, rats had access to chow or an HFC diet (cookies, peanuts, chow) for 1 month. Male and female NH and MS rats that consumed the HFC diet increased their caloric intake, body weight, and serum insulin levels; fat weight increased in all groups except in MS males, and serum leptin concentration increased only in females. Mediobasal hypothalamus (MBH) Pomc expression increased in NH-HFC females and Npy decreased in NH-HFC males. MS males showed insulinemia and hypercortisolemia that was attenuated by the HFC diet. The HPT axis activity response to an HFC diet was sex-specific; expression of MBH thyrotropin-releasing hormone-degrading ectoenzyme (Trhde) increased in NH and MS males; serum TSH concentration decreased in NH males, and T4 increased in NH females. In a second experiment, rats were fed chow or an HFC diet from Pd30 or 60 until Pd160 and exposed to 1 h restraint before sacrifice. Regardless of neonatal stress, age of diet exposition, or sex, the HFC diet increased body and fat weight and serum leptin concentration; it induced insulinemia in males, but in females only in Pd30 rats. The HFC diet's capacity to curtail the hypothalamus-pituitary-adrenal axis response to restraint was impaired in MS males. In restrained rats, expression of Trh in the paraventricular nucleus of the hypothalamus, Dio2 and Trhde in MBH, and serum thyroid hormone concentration were altered differently depending on sex, age of diet exposition, and neonatal stress. In conclusion, metabolic alterations associated to an HFC-diet-induced obesity are affected by sex or time of exposition, while various parameters of the HPT axis activity are additionally altered by MS, pointing to the complex interplay that these developmental influences exert on HPT axis activity in adult rats.