Childhood and adolescent obesity: Issues and viewpoints

Childhood obesity, which often persists into adulthood (Eddy et al., 2007; Must & Anderson, 2003), has become an increasingly prominent public health problem. While the psychological effects of obesity have been appreciated (Erermis et al., 2004), there is also increasing evidence that it increases the risk of medical illnesses such as diabetes mellitus, coronary heart disease and hypertension with substantial associated public health impact (Lau et al., 2007; Maloney, 2011). Over the past few decades, childhood obesity has progressively become a worldwide epidemic, with its prevalence having increased in most countries of the world (Wang & Lobstein, 2006). In the USA alone, the prevalence of obesity in children and adolescents during the years 2009 and 2010 was recently estimated to approach 17% (Ogden et al., 2012). These considerations were the impetus for the focus of this issue of the International Review of Psychiatry being childhood and adolescent obesity.

As the prevalence of childhood obesity has increased, so have the depth and breadth of publications examining the issue. Despite advances in certain areas of relevant research, such as genetics, much less is known about other aspects of childhood obesity, such as pharmacological treatment options. There are still many fundamental issues to be addressed. For instance, although many children will eat high calorie foods, not every child will become overweight or obese. Childhood obesity can be viewed as a multifaceted problem that can benefit from an interdisciplinary approach integrating basic and clinical sciences. Biological factors (such as genetics, epigenetics and intrauterine environment), as well as behavioural (such as learned eating behaviour) and social factors (such as socio-economic status) may all contribute to childhood obesity.

Given the worldwide childhood obesity epidemic, psychiatrists and other mental health practitioners encounter childhood overweight and obesity quite often in their practices. The co-occurrence of obesity and psychiatric illness is common given the high prevalence of both psychiatric disorders (Merikangas et al., 2010) and obesity (Ogden et al., 2012) independently in youths. Moreover, obesity can present as a comorbidity of psychiatric disorders, just as psychiatric disorders can present as a comorbidity of obesity. In addition, obesity can be exacerbated or even caused by many of the psychotropic medications used to treat our paediatric patients (Maayan & Correll, 2011). This special issue targets psychiatrists and other health and mental health practitioners facing these challenges.

The papers in this volume of the International Review of Psychiatry focus on issues practitioners encounter concerning the clinical management of childhood obesity. The goal is to critically review the available evidence regarding multifaceted topics ranging from the basic sciences (such as genetics) to clinical approaches (such as psychosocial treatments), while also presenting the narrative viewpoints of the authors.

This volume begins with an exploration of the epidemiology of childhood obesity.

Youfa Wang and colleagues from the Johns Hopkins Global Center on Childhood Obesity and the Johns Hopkins Bloomberg School of Public Health review the global epidemic of childhood obesity, which has increased over the past decade to become a global public health crisis. The association between childhood obesity and socio-economic status (SES) is also reviewed. Notably, the groups with greater access to energy-dense foods (low SES in industrialized countries and the reverse in developing countries) have more of a chance to become obese.

A major emphasis of this issue is on the basic aetiological mechanisms of childhood obesity. The developmental aetiology of childhood obesity, as well as specific genetic contributions, neuroimaging evidence of reward pathway involvement and the influence of diet and sensitive developmental periods in taste preference are explored. First, Susan Carnell and colleagues from Columbia University present views about the aetiology of childhood obesity, and present a biobehavioural susceptibility model as a mechanistic framework to understand variability in appetitive traits and individual weight in obese youths. Genetics also plays an important role in the aetiology of childhood obesity, as described by Joanne Cecil from the University of St Andrews in the UK. Cecil and colleagues describe the role of the allelic variants of certain specific genes to mediate susceptibility to childhood obesity primarily through food consumption and appetite regulation. Michael Michaelides, Gene-Jack Wang and colleagues from Brookhaven National Laboratory and Mount Sinai University review evidence of altered brain function in obesity from neuroimaging studies. Magnetic resonance imaging literature supports the dysregulation of frontostriatal circuits involved in motivation for food reward and eating self-regulation as contributing to obesity. Animal and human positron emission tomography imaging methods have demonstrated a blunted striatal dopamine release with food stimulation in both obesity and binge eating disorder. The authors also provide insights into how the field of imaging youths might also advance using animal models. Jillian Trabulsi and Julie Mennella from the University of Delaware and Monell Institute review the role of diet and sensitive periods in flavour learning that may affect later food preferences and health outcomes such as childhood obesity.

Another focus of the issue is clinical aspects of childhood obesity including paediatric medical comorbidity, psychiatric comorbidity, and body image development in obese youths. Ann Scheimann from Johns Hopkins University describes general medical comorbidity in obese paediatric patients, issues the psychiatrist may face when treating such patients, and pharmacological treatment options. Given that psychiatric comorbidity is expected in childhood obesity, Melissa Kalarchian and Marsha Marcus from the University of Pittsburgh and Western Psychiatric Institute and Clinic review the evidence and provide viewpoints describing how psychiatric comorbidity may either be a cause or consequence of childhood obesity. The authors review the literature regarding obese youths with disordered eating, particularly loss-of-control eating, as well as other psychiatric diagnoses such as ADHD and mood disorders, which may be comorbid with obesity. Obese youths may also suffer body image issues, low self-esteem and weight bias as a consequence of their weight status, as explored by Jennifer Harriger and Kevin Thompson from the University of Florida.

The final section of this issue presents viewpoints regarding specific treatment options including bariatric surgery and psychosocial treatments. Heather Austin from the University of Alabama, and colleagues describe pro and con viewpoints regarding bariatric surgery as a treatment option for select patients with severe adolescent obesity when other options have failed. Marian Tanofsky-Kraff from the Uniformed Services University of the Health Sciences presents psychosocial preventive interventions for youths with obesity. The manuscript reviews psychosocial treatments for obesity and loss of control eating and specifically examines interpersonal therapy for the prevention of excessive weight gain as well as its use in underserved minorities and military dependent populations.

The papers in this issue illustrate the utility of using various basic science and translational investigations, including genetics and neuroimaging, to understand childhood obesity. As future technological advancements will allow us even safer neuroimaging techniques, we will be able to directly assess neurotransmitter activity in children and better understand the developmental trajectory of reward pathways. Advances in basic science research will continue to inform translational research and clinical research that will subsequently lead to the development of targeted treatments for childhood obesity. These papers also indicate that more interdisciplinary translational research is necessary to shape paediatric obesity treatment strategies and target our treatments more effectively.

It is hoped that the manuscripts included in this special issue convey the exciting advances in the field as well as issues and viewpoints that have arisen from these advances. These viewpoints will hopefully encourage further potential questions to fuel research in childhood obesity particularly regarding the aetiology of childhood obesity and further effective treatments. We are grateful to the authors and reviewers for their superb contributions to this issue and thank the editors for their invitation to generate this issue.

Acknowledgement

We thank Gwenn Smith and Mark Riddle for helping with the organization, development and editing of this volume. Preparation of this manuscript was supported in part by the US National Institutes of Health, National Institute of Mental Health, Grant K23MH083000 (S.P. Reinblatt), and the National Institute of Child Health and Human Development supported the Johns Hopkins Global Center for Childhood Obesity, U54 HD070725.