The amygdala is a part of the so-called limbic system that performs a primary role in the processing of memory, decision-making, and emotional reactions. The amygdala has also been implicated in a variety of mental health problems including anxiety, binge drinking and post-traumatic stress syndrome.
A study by Xu and colleagues, published in the Journal of Clinical Investigation now shows that in mice, activity of the estrogen receptor–α (ERα) in the medial amygdala may have a profound influence on the development of obesity – an effect, which appears to me largely mediated through effects on physical activity.
Building on previous work showing that ERα activity in the brain prevents obesity in both males and female rats, the researchers used a series of complex experiments to demonstrate that specific deletion of the ERα gene from SIM1 neurons, which are highly expressed in the medial amygdala, cause a marked decrease in physical activity and weight gain in both male and female mice fed with regular chow, without any increase in food intake. In addition, this deletion caused increased susceptibility to diet-induced obesity in males but not in females.
Deletion of the ERα receptor also blunted the body weight-lowering effects of a glucagon-like peptide-1-estrogen (GLP-1-estrogen) conjugate.
In contrast, over-expression or stimulation of SIM1 neurons increased physical activity in mice and protected them from diet-induced obesity.
These findings point to a novel mechanism of neuronal control of physical activity, which in turn appears to have important effects on the susceptibility to weight gain.
Today’s guest post comes from Kristy Wittmeier, PhD (and CON Bootcamper), a physiotherapist at the Winnipeg Health Sciences Centre and Director of Knowledge Translation at the Manitoba Centre for Healthcare Innovation. She has a special interest in physical activity as a tool to prevent and manage obesity-related conditions in youth. Her current positions and affiliation with the Children’s Hospital Research Institute of Manitoba allow her to combine research and practice to improve patient outcomes. Twitter: @KristyWittmeier
If you were trying to build a coordinated provincial strategy to promote healthy weight in children and youth, where would you start? This has been a question on the minds of a team of healthcare providers and researchers in Manitoba for some time now.
Manitoba has the highest rate of type 2 diabetes in children in Canada, a condition that is in part related to obesity. In Manitoba, youth are diagnosed with type 2 diabetes at a rate 20 times higher than in any other province.
There are well-established, multidisciplinary clinical programs in our province that work with youth living with type 2 diabetes. For example, the Diabetes Education Resource for Children and Adolescents, which has existed since 1985, runs two weekly clinics and an outreach program for youth affected by type 2 diabetes.
Recently, the diabetes care team joined forces with pediatric kidney specialists in the province to provide a combined clinic for youth affected by both type 2 diabetes and kidney complications.
Manitoba is also home to the Maestro Project, which helps teens living with type 2 diabetes navigate what could otherwise be a difficult transition from pediatric to adult health care services and teams.
Similarly, research teams that include community advisors and families are tackling important questions related to the origins of type 2 diabetes and exploring innovative interventions to improve the health and quality of life for kids with this diagnosis.
Members of the DREAM (Diabetes Research Envisioned and Accomplished in Manitoba) Theme at the Children’s Hospital Research Institute of Manitoba are studying important biological, social and psychological factors linked with early kidney disease in youth with type 2 diabetes in a study called iCARE (Improving renal Complications in Adolescents with type 2 diabetes through REsearch).
While we have made significant progress in the area of type 2 diabetes care and research, we have made less progress in the areas of prevention and treatment of obesity in children and youth. We are one of the few provinces in Canada without a specialized clinical team dedicated to pediatric obesity. We lack a comprehensive provincial strategy that can link health care providers to each other, or to existing community programs that might help families. Gaps in services can leave families without access to care that could help their children. This is the issue that we have decided to tackle in a study that was recently funded by the Children’s Hospital Research Institute of Manitoba.
Our study is called “Mapping the state of pediatric weight management programs in Manitoba.” We will start with a survey within Manitoba, to identify existing programs that are available to families affected by obesity in our province. We want to know what is currently available. Where can health care providers refer families? And importantly, what resources are missing in our province to be able to provide an evidence-based approach to pediatric weight management?
While the title suggests we are solely focused on Manitoba, we are in fact looking to shape our provinces’ approach by learning from others across Canada and the United States.
To do this, the second part of the study will involve updating a 2010 study that mapped Canadian pediatric weight management programs to understand what has changed on the national landscape. What new programs exist and where? What programs are no longer offered and why?
Then we will move on to more in-depth conversations with members of the eight clinics involved in the Canadian Pediatric Weight Management Registry (CANPWR), and an additional eight clinics in the United States to better understand how their approaches evolved, barriers and successes that they have experienced and other key learnings that they can share to help inform a Manitoba approach.
Once we have brought the information from these activities together, we will hold a meeting for families, community members, clinicians, researchers, healthy living organizations and policy makers in the province. We will look at the data together and prioritize the next important steps on this journey.
We all need to work together to build healthier families, healthier communities and healthier populations. This novel approach that integrates the experiences and priorities of others will ensure that when we launch a new direction for pediatric obesity management in Manitoba, it will be relevant and targeted to everyone’s needs.
The recent report card on physical activity released by Participaction strongly recommends (unsupervised) free play as a means to increase physical activity in kids.
But free play has far greater benefits on children’s development than just physical fitness, especially when there is an element of risk involved.
That is the conclusion of a paper by Marianna Brussoni and colleagues, published in the International Journal of Environmental Research and Public Health.
For their paper, risky play was defined as play that involves an element of danger, including the possibility of physical injury. Such types of play include play at height, speed, near dangerous elements (e.g., water, fire), with dangerous tools, rough and tumble play (e.g., play fighting), and where there is the potential for disappearing or getting lost.
This systematic review of 21 relevant research studies shows that risky outdoor play not only improves physical health (despite the inherent risk of injuries and even death), but also social health and behaviours, risk for injuries, and reduced aggression.
Specifically, studies have shown improvements in risk detection and competence, increased self-esteem and decreased conflict sensitivity and conflict resolution, better developed motor skills, enhanced social behaviour, greater independence, improved risk management strategies, and the ability to negotiate decisions about substance use, relationships and sexual behaviour during adolescence.
Obviously, risky behaviour is risky – according to the researchers,
“In Canada, approximately 2,500 children age 14 and under are hospitalized annually as a result of playground falls (play at height)—81% are for fractures.”
Nevertheless, weighing all of the available evidence, the researchers came to the following conclusions:
“Although these findings are based on ‘very low’ to ‘moderate’ quality evidence, the evidence suggests overall positive effects of risky outdoor play on a variety of health indicators and behaviours in children aged 3-12 years. Specifically, play where children can disappear/get lost and risky play supportive environments were positively associated with physical activity and social health, and negatively associated with sedentary behaviour.
Play at height was not related to fracture frequency and severity. Engaging in rough and tumble play did not increase aggression, and was associated with increased social competence for boys and popular children, however results were mixed for other children.
There was also an indication that risky play supportive environments promoted increased play time, social interactions, creativity and resilience.
These positive results reflect the importance supporting children’s risky outdoor play opportunities as a means of promoting children’s health and active lifestyles.”
Clearly, these finding go against the popular policies that focus on harm reduction and making kids’ play environments as safe as possible.
Perhaps these policies are doing more harm than good – as always, you never know where the unintended consequences of well-meant public policies rear their ugly head.
This week, Participaction released the 2015 report card on activity in Canadian kids (a yearly exercise formerly undertaken by Healthy Active Kids), and its message is simple – send your kids outside to play!
This is how Participaction defines the protection paradox:
“We may be so focused on trying to intervene in our children’s lifestyles to make sure they’re healthy, safe and happy, that we are having the opposite effect….We overprotect kids to keep them safe, but keeping them close and keeping them indoors may set them up to be less resilient and more likely to develop chronic diseases in the long run.”
And it works best when you send the kids out alone – here is what research shows:
- Grade 5 and 6 students who are often or always allowed to go out and explore unsupervised get 20% more heart- pumping activity than those who are always supervised.
- 3- to 5-year-old kids are less likely to be active on playgrounds that are designed to be “safer,” because many kids equate less challenging with boring.
- Children and youth are less likely to engage in higher levels of physical activity if a parent or supervising adult is present.
Safe is boring – who would have guessed?
And here’s even more research to support this idea:
- Kids with ready access to unsupervised outdoor play have better-developed motor skills, social behaviour, independence and conflict resolution skills.
- Adventure playgrounds and loose parts playgrounds, which support some exposure to “risky” elements, lead to an increase in physical activity and decrease in sedentary behaviours.
“We need to consider the possibility that rules and regulations designed to prevent injuries and reduce perceived liability consequences have become excessive, to the extent that they actually limit rather than promote children’s physical activity and health. Adults need to get out of the way and let kids play.”
Time to set your kids free!
However, it turns out that perhaps one of the most powerful predictors of mortality is a simple and inexpensive assessment of grip strength – something rarely assessed in clinical practice.
Now, a study by Darryl Leung and colleagues, in a paper published in The Lancet, reports that grip strength does just that.
The paper presents data from the Prospective Urban-Rural Epidemiology (PURE) study, a large, longitudinal population study done in 17 countries of varying incomes and sociocultural settings involving nearly 150,000 individuals.
During a median follow-up of 4·0 years, grip strength (as a simple measure of muscular strength) was found to be inversely associated with all-cause mortality (hazard ratio per 5 kg reduction in grip strength 1·16), cardiovascular mortality (1·17), non-cardiovascular mortality (1·17), myocardial infarction (1·07), and stroke (1·09).
In fact, grip strength was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure.
In contrast, grip strength was not associated with diabetes, hospital admission for pneumonia or COPD, injury from fall, or fracture.
Interestingly, the association between grip strength and cardiovascular mortality is not new – however, the association with all-cause mortality and the consistency of this findings across populations and economic strata is remarkable.
Obviously, these findings beg the question whether increasing grip strength (or rather muscular strength in general) through resistance training and adequate protein intake will lower mortality – a question that would take a rather large randomised controlled study to answer.
Till then, it is prudent to remember that association does not prove causation – it would thus be premature to conclude that your weak handshake is killing you.