Excess body fat increases the risk of depression

A new study from Aarhus University and Aarhus University Hospital, Denmark, shows that ten kilograms of extra body fat increases the risk of depression by seventeen percent.

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Carrying ten kilograms of excess body fat increases the risk of depression by seventeen per cent. The more fat, the greater the probability of developing depression. This is the main conclusion of a new study carried out by researchers from Aarhus University and Aarhus University Hospital, Denmark.

"Our study also indicated that the location of the fat on the body makes no difference to the risk of depression. This suggests that it is the psychological consequences of being overweight or obese which lead to the increased risk of depression, and not the direct biological effect of the fat. If the opposite was true we would have seen that fat located centrally on the body increased the risk the most, as it has the most damaging effect in biological terms," says the study's last author Dr. Søren Dinesen Østergaard. 

He is professor at the Department of Clinical Medicine at Aarhus University and affiliated with the Department of Affective Disorders at Aarhus University Hospital. 

Prior studies in the field have predominantly used Body Mass Index (BMI) to measure obesity. BMI is calculated solely on the basis of body weight and height and is therefore a fairly crude measure, that does not, for example, take build and muscle mass into account.

"BMI is an inaccurate way of measuring overweight and obesity. Many elite athletes with a large muscle mass and a low body fat mass will have a BMI above 25, which is classified as overweight according to the common definition. This obviously doesn't make much sense. Therefore, one of the strengths of our study is that we've been able to zoom in and look at the specific relationship between the amount of body fat and the risk of depression," explains Dr. Østergaard.

In the study, which has been published in the journal Translational Psychiatry, the researchers have analysed data from two large genetic data sets: the UK Biobank, which contains data on the correlation between genetic variants and physical measurements (including body fat mass distributed around parts of the body); and the Psychiatric Genomics Consortium, which contains information on the correlation between genetic variants and depression.

Dr. Østergaard also highlights his research group's choice of the 'Mendelian randomization' method as the main reason why the study was successful. He also emphasises that the findings are particularly significant in light of the fact that almost 40 per cent of the world's adult population is overweight. 

"In addition to the known physical consequences of obesity such as diabetes and cardiovascular disease, there is also a significant and now well-documented psychological component, which needs to be dealt with as well. This is yet another argument for resolving the obesity epidemic," he says, before emphasising that it is important to have a balanced approach to the issue: 

"As it appears to be the psychological consequences of obesity, such as a negative body image and low self-esteem that is the main driving force behind the increased risk of depression, society's efforts to combat obesity must not stigmatise, as this will probably increase the risk of depression even further. It is important to bear this in mind so we can avoid doing more harm than good in the effort to curb the obesity epidemic," says Dr. Østergaard. 

FACTS ABOUT MENDELIAN RANDOMIZATION:

Mendelian randomization (named after the Austrian monk Gregor Mendel, who was the father of modern genetics) is a method which in recent years has helped researchers to overcome a major challenge associated with observational studies - namely that of making causal inference. In observational studies researchers often find correlations between two conditions - e.g. between obesity and depression - where it is difficult, or rather impossible, to determine whether there is indeed a causal effect going from obesity to depression - or vice versa. Mendelian randomization may solve this challenge.

Mendelian randomization can be described as nature's version of the randomised controlled trials that are carried out when testing whether a new drug has the desired (causal) effect in the treatment of a disease. In the clinical trials of drugs, lots are drawn to determine whether individual participants will receive the active drug or a placebo, without them knowing which treatment they have been assigned to. Instead, Mendelian randomization takes advantage of the fact that a completely natural randomization takes place during the formation of the sex cells (egg cells and sperm cells), which represent the origin of all human beings. When sex cells are formed, the parents' genetic variants - including those that give rise to increased body fat- are randomly distributed. Therefore, some individuals will have received many of these variants and others less. In the study in question, the researchers have utilised this natural and random source of variation to determine whether people who have received many genetic variants for increased body fat have an increased risk of suffering depression.

THE RESEARCH RESULT - MORE INFORMATION

Genetic epidemiological study utilising data from the UK Biobank (with information on the association between genetic variants and fat mass based on a study of 330,000 people) and the Psychiatric Genomics Consortium (with information on the association between genetic variants and depression based on a study of 135,000 people with depression and 345,000 control subjects).

The research group comprises Maria S. Speed, Oskar H. Jefsen, Anders D. Børglum, Doug Speed and Søren D. Østergaard - all from Aarhus University.

Nearly 20 percent of suicidal youths have guns in their home

Researchers say emergency department doctors should screen all pediatric patients for suicide risk WASHINGTON, DC – Nearly one in five children and teens found to be at risk for suicide report that there are guns in their homes, and 15 percent of those at risk for suicide with guns in the home know how to access both the guns and the bullets, according to a study to be presented Monday, May 6, at the Pediatric Academic Societies (PAS) annual meeting in Washington, DC. Suicide is the second leading cause of death among young people ages 10 to 24 years in the United States, according to Centers for Disease Control and Prevention data. Nearly half of youths who die by suicide use a firearm. Researchers conducted a study to create a suicide risk screening tool that health care professionals in emergency departments (EDs) could use to figure out which youths need further mental health evaluation to keep them from harming themselves. As part of that study, researchers asked youths about access to guns in or around their home and about gun/bullet storage. "For more than 1.5 million adolescents, the ED is their primary point of contact with the health care system, which makes the ED an important place for identifying youth at risk for suicide," said Stephen J. Teach, MD, MPH, FAAP, associate chief in the Division of Emergency Medicine at Children's National Medical Center in Washington, DC, and co-author who will be presenting the study at the PAS meeting. Many clinicians and parents do not know how to ask youth about suicide, so they require screening tools to assist in detection, added study senior author Lisa M. Horowitz, PhD, MPH, staff scientist/pediatric psychologist at the National Institute of Mental Health, National Institutes of Health, Bethesda, Md. "According to our data, when asked their opinion, nearly all of the kids in our study were in favor of suicide screening in the ED. Our study shows that if you ask kids directly about suicide, they will tell you what they are thinking." Study participants included 524 patients ages 10 to 21 who were seen for medical/surgical or psychiatric complaints at one of three pediatric EDs. They were asked to fill out a 17-item questionnaire that the researchers used to develop the Ask Suicide-Screening Questions (ASQ), a four-question screening tool that can be used for all pediatric patients visiting the ED. The ASQ has been validated against a longer more in-depth suicide assessment tool. "While many youths who kill themselves have mental health disorders, up to 40 percent of youths who kill themselves have no known mental illness," said co-author and youth suicide expert Jeffrey A. Bridge, PhD, principal investigator at The Research Institute at Nationwide Children's Hospital and associate professor of pediatrics at The Ohio State University. "Therefore, it is important to screen all children and adolescents for suicide, regardless of the reason they are visiting the ED." Of the patients who completed the screening tools, 151 (29 percent) were found to be at risk for suicide, and 17 percent of them reported guns in or around the home. Of those at risk for suicide and reporting guns in the home, 31 percent knew how to access the guns, 31 percent knew how to access the bullets, and 15 percent knew how to access both the guns and the bullets. "This study highlights the importance of parents understanding the risks of having guns in their homes," said Dr. Bridge. "Being at risk for suicide and having access to firearms is a volatile mix. These conversations need to take place in the ED with families of children at risk for suicide." Suicide Prevention CE Course ### To view the abstract, "Access to Firearms among Patients Screening Positive for Suicide Risk in Pediatric Emergency Departments," go to http://www.pas-meeting.org/2013DC/Abstracts/LB%20Pub%20All%202013.pdf The research was supported by the Intramural Research Program of the National Institute of Mental Health, the National Institutes of Health (Drs. Horowitz & Pao); institutional research funds from the Research Institute at Nationwide Children's Hospital and grant K01 MH-69948 from the National Institute of Mental Health (Dr. Bridge); institutional research funds from the Program for Patient Safety and Quality at Boston Children's Hospital Boston (Dr. Wharff). The Pediatric Academic Societies (PAS) are four individual pediatric organizations that co-sponsor the PAS Annual Meeting – the American Pediatric Society, the Society for Pediatric Research, the Academic Pediatric Association, and the American Academy of Pediatrics. Members of these organizations are pediatricians and other health care providers who are practicing in the research, academic and clinical arenas. The four sponsoring organizations are leaders in the advancement of pediatric research and child advocacy within pediatrics, and all share a common mission of fostering the health and well-being of children worldwide. For more information, visit http://www.pas-meeting.org. Follow news of the PAS meeting on Twitter at http://twitter.com/PedAcadSoc.