(Press-News.org) Increased adiposity is likely to cause reduced physical activity in children, according to research published in this week's PLOS Medicine. The results of the study, conducted by Rebecca Richmond and colleagues from the MRC Integrative Epidemiology Unit at the University of Bristol, UK, suggest that promoting weight loss in overweight and obese children might also increase childhood activity levels.
Previous studies have shown an association between low physical activity and higher body mass index (BMI) in children but were not able to determine whether childhood adiposity influences physical activity levels. To address this question, the authors analyzed a panel of genes reliably associated with adiposity to examine whether children with a genetic predisposition for increased BMI were more likely to have lower rates of physical activity, which would imply a causal effect.
Because there are no common genetic variants known to be linked to reduced physical activity, the researchers could not investigate whether the reverse is also true, namely that genetic predisposition to lower physical activity might also cause higher BMI.
They studied a group of children from the Avon Longitudinal Study of Parents and Children (Children of the 90s/ALSPAC) and measured their BMI and total body fat. A small movement-counting device also recorded the total daily activity of 5,595 of the children. In addition, the researchers examined the children's genetic make-up for the presence of variants known to be linked to obesity. By applying Mendelian randomization, a method of using measured variation in genes of known function to assess the causal effect of a modifiable exposure on disease, the authors showed that greater BMI is likely to be causally associated with lower daily activity. Specifically, the analysis demonstrated that for every 3.3 kg/m2 increase in BMI, the children recorded ~2.8 less minutes per day of moderate-to-vigorous-intensity activity.
The findings show that obese children have a propensity to reduced levels of physical activity, which may in turn lead to further weight gain, and support targeting weight reduction in efforts to increase childhood activity levels. According to the authors,
"The study illustrates how genetics can be used to help find causal relationships in complex networks of observational measurements. It is intuitive to think of and observe relationships between factors such as obesity and activity in the population, however it is less clear in which direction these associations lie, whether they are causal or whether it is worth allocating considerable resources to assessing the impact of potential interventions."
INFORMATION:
Funding: RCR is funded by the Wellcome Trust 4-year studentship (Grant Code: WT083431MF). NJT, GDS, and GM work within the Integrative Epidemiology Unit (IEU), which is supported by the MRC (MC_UU_12013/1 and MC_UU_12013/3) and the University of Bristol. ARN works within the NIHR Biomedical Research Unit at the University of Bristol and the University Hospitals Bristol NHS Foundation Trust in Nutrition, Diet and Lifestyle. The UK Medical Research Council and the Wellcome Trust (Grant ref: 092731) and the University of Bristol provide core support for ALSPAC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: GDS is a member of the Editorial Board of PLOS Medicine. All other authors have declared that no competing interests exist.
Citation: Richmond RC, Smith GD, Ness AR, Hoed Md, McMahon G, et al. (2014) Assessing Causality in the Association between Child Adiposity and Physical Activity Levels: A Mendelian Randomization Analysis. PLoS Med 11(3): e1001618. doi:10.1371/journal.pmed.1001618
IN YOUR COVERAGE PLEASE USE THIS URL TO PROVIDE ACCESS TO THE FREELY AVAILABLE PAPER:
http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1001618
Contact:
Nicholas Timpson
University of Bristol
UNITED KINGDOM
+44 117 3310131
N.J.Timpson@bristol.ac.uk
Increased adiposity and reduced physical activity in children: Cause or effect?
2014-03-18
ELSE PRESS RELEASES FROM THIS DATE:
1 in 3 patients with bloodstream infections given inappropriate therapy
2014-03-18
DURHAM, N.C. -- Growing drug resistance, a high prevalence of S. aureus bacteria and ineffective antibiotics prescribed to one in three patients are among the challenges facing community hospitals in treating patients with serious bloodstream infections, according to researchers at Duke Medicine.
The findings, published March 18, 2014, in the journal PLOS ONE, provide the most comprehensive look at bloodstream infections in community hospitals to date. While the majority of people in need of medical care go to community hospitals, much of the existing research on bloodstream ...
Penn Medicine researchers show how lost sleep leads to lost neurons
2014-03-18
PHILADELPHIA - Most people appreciate that not getting enough sleep impairs cognitive performance. For the chronically sleep-deprived such as shift workers, students, or truckers, a common strategy is simply to catch up on missed slumber on the weekends. According to common wisdom, catch up sleep repays one's "sleep debt," with no lasting effects. But a new Penn Medicine study shows disturbing evidence that chronic sleep loss may be more serious than previously thought and may even lead to irreversible physical damage to and loss of brain cells. The research is published ...
Stem cells from muscle can repair nerve damage after injury, Pitt researchers show
2014-03-18
PITTSBURGH, March 18, 2014 – Stem cells derived from human muscle tissue were able to repair nerve damage and restore function in an animal model of sciatic nerve injury, according to researchers at the University of Pittsburgh School of Medicine. The findings, published online today in the Journal of Clinical Investigation, suggest that cell therapy of certain nerve diseases, such as multiple sclerosis, might one day be feasible.
To date, treatments for damage to peripheral nerves, which are the nerves outside the brain and spinal cord, have not been very successful, ...
Trends in food supplements differ from country to country, new study finds
2014-03-18
A new study, published today in the journal in PLOS ONE, shows which plant food supplements are most popular across Europe, with consumers using them to complement their diets or to maintain health.
The team of researchers from the Fundación para la Investigación Nutricional and the University of Surrey found that these products are taken in many different forms, including in tea, juice or by tablet. They analysed data from six European countries, collecting information from 2359 adult consumers of plant food supplements in Finland, Germany, Italy, Romania, Spain and ...
Risk of psychiatric diagnoses, medication use increases after critical illness
2014-03-18
Critically ill patients receiving mechanical ventilation had a higher prevalence of prior psychiatric diagnoses and an increased risk of a new psychiatric diagnosis and medication use after hospital discharge, according to a study in the March 19 issue of JAMA.
With recent advances in medical care, more patients are surviving critical illness. Critically ill patients are exposed to stress, including pain, respiratory distress, and delirium, all of which may impact subsequent mental health. The extent of psychiatric illness prior to critical illness, as well as the magnitude ...
Pregnancy associated with greater risk of certain bacterial infection; may worsen outcomes
2014-03-18
In a surveillance study of infection with the bacterium Haemophilus influenzae among women of reproductive age in England and Wales from 2009-2012, pregnancy was associated with a greater risk of this infection, which was associated with poor pregnancy outcomes such as premature birth and stillbirth, according to a study in the March 19 issue of JAMA.
Haemophilus influenzae can cause illnesses that include respiratory infections. Some studies have suggested an increased risk of invasive H influenzae disease during pregnancy, although these were based on a small number ...
Study examines use of age-adjusted D-dimer levels to exclude lung blood clots
2014-03-18
Using a patient's age to raise the threshold for an abnormal result of a blood test used to assess patients with a suspected pulmonary embolism (blood clot in lungs) appeared to be safe and led to fewer healthy patients with the diagnosis, according to a study in the March 19 issue of JAMA.
D-dimer is a breakdown product of a blood clot, and measuring D-dimer levels is one way doctors exclude a diagnosis of pulmonary embolism (PE). Several studies have shown that D-dimer levels increase with age. As a result, the proportion of healthy patients with abnormal test results ...
Children with glomerular kidney disease more likely to have hypertension as adults
2014-03-18
Men who as children had glomerular disease, a disorder of the portion of the kidney that filters blood and one that usually resolves with time, were more likely than men without childhood glomerular disease to have high blood pressure as an adult, according to a study in the March 19 issue of JAMA.
Glomerular disease was defined for this study as glomerulonephritis or nephrotic syndrome (both are kidney disorders). Most children who develop glomerular disease have a favorable prognosis with complete resolution of all signs and symptoms. Yet the long-term complications ...
Study finds no evidence that vitamin D supplements reduce depression
2014-03-18
NEW YORK, NY (March 18, 2014) — Vitamin D deficiency has been implicated in numerous health conditions in recent years, including depressed mood and major depressive disorder. Recent observational studies provide some support for an association of vitamin D levels with depression, but the data do not indicate whether vitamin D deficiency causes depression or vice versa. These studies also do not examine whether vitamin D supplementation improves depression.
A systematic review of clinical trials that have examined the effect of vitamin D supplementation on depression ...
JCI online ahead of print table of contents for March 18, 2014
2014-03-18
Cardiac conduction altered by intragenic enhancer
Genome-wide association studies (GWAS) have determined a surprising link between dysfunctional cardiac conduction and variants within SCN10A, which encodes nociceptor-associated sodium-gated ion channel subunit NaV1.8. Follow-up functional studies targeting NaV1.8 revealed only a minor contribution to cardiac physiology; therefore, it was unclear how SCN10A mutations promoted the development of cardiac conduction disease. In this issue of the Journal of Clinical Investigation, the research groups of Vincent Christoffels, ...