Do obesity and mental ill-health go “hand in hand”? Research suggests so

29 Apr 2019 --- Obesity may increase the risk of developing anxiety and depression in children and adolescents. This is according to separate research from Sweden and the UK – both to be presented at this year’s European Congress on Obesity (ECO) in Glasgow, UK, on the 28 April to 1 May. The Swedish study has noted that obesity is an independent risk factor for anxiety and depression in young people, while British researchers identified that obesity and emotional problems seem to develop concurrently as children grow up.

Obesity rates are rising worldwide. According to the World Health Organization (WHO), global obesity numbers have nearly doubled since 1980 and more than 40 million children under the age of five were overweight in 2011. Apart from its negative impacts on mental health and development, obesity can cause serious metabolic implications. Excess body weight was responsible for roughly 4 percent of cancers worldwide in 2012, and that number is likely to rise, an American Cancer Society peer-reviewed study found last year.

The Swedish study found that girls with obesity were 43 percent more likely to develop anxiety or depression compared to their peers in the general population. Similarly, boys with obesity faced a 33 percent increased risk for anxiety and depression compared to their counterparts. The study compared over 12,000 Swedish children who had undergone obesity treatment with more than 60,000 matched controls. 

Meanwhile, researchers from the University of Liverpool and University College London found that obesity and emotional problems tended to occur together in mid-childhood and adolescence, from ages seven to 14, but not in early childhood, at ages three and five. Girls had, on average, higher BMI and emotional symptoms than boys from ages seven to 14, but co-occurrence and development of obesity and mental ill-health were similar for both. The study analyzed data on more than 17,000 children born across the UK in 2000-2001, taking part in the Millennium Cohort Study.  Anxiety and depression are reported to be more common in children with obesity than in children of healthy weight.

Anxiety and depression appear to be more common in obese teens
Anxiety and depression are reported to be more common in children with obesity than in children of healthy weight, note the Swedish researchers, but it is unclear whether the association is independent of other known risk factors. Previous studies are hampered by methodological limitations including self-reported assessment of anxiety, depression and weight.

“We see a clear increased risk of anxiety and depressive disorders in children and adolescents with obesity compared with a population-based comparison group that cannot be explained by other known risk factors such as socioeconomic status and neuropsychiatric disorders,” says Louise Lindberg from the Karolinska Institutet, Stockholm, Sweden, who led the research. “These results suggest that children and adolescents with obesity also have an increased risk of anxiety and depression, something that healthcare professionals need to be vigilant about.”

To provide more evidence, the Swedish researchers conducted a further nationwide population-based study to investigate whether obesity is an independent risk factor for anxiety or depression. The study examined 12,507 cases of children aged six to 17 years from the Swedish Childhood Obesity Treatment Register, between 2005 and 2015. The subject group was compared to 60,063 controls from the general population, matched for sex, year of birth and living area.

The research team adjusted for a range of factors known to affect anxiety and depression including migration background, neuropsychiatric disorders, parental psychiatric illness and socioeconomic status. A total of 4,230 children and adolescents developed anxiety or depression over an average of 4.5 years.

Obesity was clearly linked to a higher risk of anxiety and depression in childhood and adolescence. Girls (11.6 percent versus 6 percent) and boys (8 percent versus 4.1 percent) with obesity were more likely to be diagnosed with anxiety and depression than those in the general population over the study period. Negative thinking, low self-esteem and impaired stress is more common in girls than in boys, which may be one of the reasons we see higher rates in girls compared to boys, Lindberg tells NutritionInsight.

In further analyses, excluding children with neuropsychiatric disorders or a family history of anxiety or depression, the risks were found to be even higher. In particular, boys with obesity were twice as likely to experience anxiety or depression as their normal-weight peers, while girls with obesity were 1.5 times more likely.

Is socioeconomic disadvantage a partial factor?
The British study found that socioeconomic disadvantage may explain part of the link between children’s obesity and mental ill-health. After taking social background into account, the association between BMI and emotional problems was reduced slightly. However, the association between BMI and emotional problems remained, with obesity at age seven a risk factor for emotional distress at age 11, and in turn, mental health problems predicting high BMI at age 14.

Both studies note that in light of the increasing association between such health conditions and obesity, early interventions from health officials that target both weight and mental health are crucial. 

This study, published in JAMA Psychiatry, found that rates of obesity and emotional problems among children increased gradually throughout childhood and adolescence. Almost 8 percent of young people were obese by age 14, and around double that number were reported to have had feelings of low mood and anxiety. By adolescence, around a fifth of those who were obese also had high levels of emotional distress.

“Although our study does not shed light on the reasons obesity and mental ill-health develop together during childhood, we can hypothesize that children with higher BMI may experience weight-related discrimination, which over time leads to increased depressive symptoms, as has been shown in adults,” says Dr. Charlotte Hardman, co-author of the study, from University of Liverpool.

Early intervention is crucial to all cases of obesity
Both studies note that in light of the increasing association between such health conditions and obesity, early interventions from health officials that target both weight and mental health are crucial. 

“As both rates of obesity and emotional problems in childhood are increasing, understanding their co-occurrence is an important public health concern, as both are linked with poor health in adulthood. The next steps are to understand the implications of their co-occurrence and how to best intervene to promote good health,” says Dr. Praveetha Patalay, co-author, University College London.

Linderg, of the Swedish study, suggests that children be screened for anxiety and depression when they first come in contact with healthcare professionals for their obesity problems, as a way to identify problems from early on.

However, further studies are needed to explain the mechanisms behind the association between obesity and anxiety and depression, Lindberg concludes.

By Laxmi Haigh