Childhood obesity and depression may be caused by shared abnormalities in the brain’s reward centers, new research suggests.
The connection between the two conditions has long been thought of as a ‘chicken and egg’-type paradox wherein overweight youths experience low-self esteem that kicks off a cycle of overeating to make themselves feel better, followed by weight gain that fuels depressive symptoms.
However, a Stanford University study published Monday found that the two conditions may actually have the same driving force: low levels in two areas of the brain responsible for rewards.
Pinpointing the specific ways these conditions affect the brain opens up the possibility of better treatments, and could help both children and parents focus less on stigma and more on solutions.
A study based on MRI scans from 42 obese children and teens with depression found a link between the conditions and low volumes in two of the brain’s reward centers
The childhood obesity epidemic affects one in five children in the US, bringing with it a range of health problems that were previously only concerns for adults including high blood pressure, high cholesterol and type two diabetes.
Children with obesity have been known to have a higher risk of developing depression, instigating a cycle that often persists into adulthood.
The team at Stanford developed the idea for the study based on previous research examining the two conditions individually that had revealed abnormalities in the brain’s reward centers.
‘Independently, in obesity and depression, the same brain networks popped up, and that was curious to us,’ said lead author Dr Manpreet Singh, a child and adolescent psychiatrist at Lucile Packard Children’s Hospital Stanford.
‘We thought maybe that was a link that would help us understand better why these symptoms coexist.’
The study published Monday in Hormones and Behavior looked at brain MRI scans of 42 children and teens between nine and 17 years old with a body-mass index greater than the 85th percentile.
Each of the participants struggled with moderate-to-severe depressive symptoms.
Standard clinical tests and questionnaires were used to evaluate each person’s level of depression and their eating behaviors, including emotional and uncontrolled eating.
OBESITY ON THE RISE IN AMERICA’S YOUNGEST CHILDREN
The rate of childhood obesity has tripled since the 1970s, affecting one in five children in the US and 14 percent of those ages two to four years old, according to CDC data released in February.
Childhood obesity is now the number one health concern among parents in the US, topping drug abuse and smoking.
Obesity continues to plague more than one third of adults in the US, and experts have warned that that proportion will only grow as younger generations do.
Over the last two decades, the US has implemented countless awareness programs to try to combat the obesity epidemic.
Former First Lady Michelle Obama became a mascot for healthier children while her husband was in office, spearheading the ‘Let’s Move’ campaign, designed to motivate children to eat healthier and stay active in an effort to promote overall health.
But in December of last year, the United States Department of Agriculture announced that it would relax the school lunch guidelines she championed – requiring more fresh fruits and vegetables and low-sugar dining options – in favor of new rules that would allow sweetened milk and sodium rich entrees.
They were also tested for insulin resistance, a dysfunction that occurs when the body’s hormone for regulating blood sugar becomes less effective.
Finally they each underwent an MRI scan to assess brain structure and function.
Overall the results revealed deficits in two areas of the brain responsible for processing rewards: the hippocampus and anterior cingulate cortex.
People with low volumes in those two areas were more likely to have high levels of insulin resistance, more severe depressive symptoms or both.
Additionally, those with more insulin resistance were more likely to eat in an unrestrained manner but they experienced less pleasure from eating and less pleasure in general.
Greater insulin resistance and greater depression were also linked to stronger connections between the two reward centers.
The study authors concluded that the findings put them one step closer to understanding the shared mechanisms behind both childhood obesity.
‘We want to help children and families understand that these conditions are brain-based phenomena,’ Dr Singh said.
The researchers are now conducting a long-term study of children and teens, including the participants from this just-completed study, to assess how their brains and clinical symptoms track together over time.
In clinical trials of future therapies, brain MRIs may help researchers evaluate how well treatments are working.
‘That’s the exciting promise of the next phase of this work: We’ll be utilizing the information we get from the brain to develop targeted, mechanistic treatments that we can then track to see if they have the effect they’re supposed to have on the brain,’ Singh said.
The researcher’s ultimate goal is to develop effective methods of preventing the conditions before they escalate and cause lasting damage.
‘With this new study, we are trying to understand the earliest age at which this vulnerability begins, and also the earliest time we will be able to intervene when we find the appropriate intervention,’ said senior author Dr Natalie Rasgon, professor of psychiatry and behavioral sciences.
‘Early intervention is important because, later in life, these are the same brain areas which will ultimately be vulnerable to neurodegenerative processes as well. It’s a double whammy.’