Reduced Reward Brain Region Size May Predict Weight Gain in Youth Facing High Financial Hardship

Findings from the nationwide longitudinal ABCD study suggest financial adversity can change brain development and raise risk for obesity.

A young boy sitting in a dimly lit room, lost in deep thought, reflecting emotional stress.

Shrinking reward-processing areas in young brains could explain why hardship leads to unhealthy weight gain.Unsplash

Published on:

09 Jul 2025, 9:30 pm

Given the rising rates of childhood obesity and its association with multiple chronic diseases, a team of Children’s Hospital Los Angeles researchers examined the relationships between financial adversity, changes in the brain, and weight gain in adolescents. Economic hardship has been associated with changes in subcortical neurodevelopment and the risk of developing obesity, but studies have yet to illuminate how these different factors interact, and in what sequence.

"We have to figure out what's the chicken or the egg," says Shana Adise, PhD, Investigator in the Center for Endocrinology, Diabetes, and Metabolism and the lead author on a study her team recently published in the Journal of Adolescent Health. “Do you have underlying differences in the brain that will cause you to overeat or crave certain foods that can lead to weight gain? Or are we observing these differences because of weight gain and food intake?”

The researchers compared a group of 3,606 youths between 9 and 12 years old who were of normal weight, overweight, or obese and experienced financial adversity, with adolescents of normal weight and with higher income.

Although similar, financial adversity and socioeconomic status are not the same. Financial adversity extends beyond the stresses of daily life and affects people across all socioeconomic levels. The researchers rated financial adversity by a summary score of respondents reporting if in the prior year they couldn't afford food, telephone service, could not pay the full amount of the rent or mortgage, were evicted, had utilities turned off from lack of payment, or could not afford medical or dental care.

The team analyzed children between 9 to 10 and 11 to 12 years old from the Adolescent Brain Cognitive Development (ABCD) Study, a nationwide longitudinal cohort study on brain development. CHLA is one of the 21 sites of this National Institutes of Health-supported study.

The study used magnetic resonance imaging (MRI) to detect subtle brain changes. Researchers found that financial adversity can influence the brain’s subcortical developmental regions associated with reward processing and control of food intake and may contribute to greater weight gain.

How stress can cause weight gain and brain changes

A stressed child surrounded by books and tempting comfort foods, with a shadowy 'stress hormone' figure at his behind.

Under pressure, the brain craves comfort — stress hormones trigger emotional eating in young minds.AI generated

We know that stress is associated with overeating and alterations to the brain. Humans have an innate biological stress response system. In modern times most of our stressors are psychological, but you still have that biological response. Your body doesn't understand it's facing psychological stressors and increases cortisol to fight or flee—even if you're just probably sitting in your chair. This causes any excess energy to be stored as fat, and your body wants to eat more because it thinks you spent energy even though you didn’t because you were sitting in 'your chair’.

Shana Adise, PhD, Investigator in the Center for Endocrinology, Diabetes, and Metabolism

The team focused on the subcortex, the center of appetite regulation that also controls some decision-making behavior. "Weight gain and stress both produce pro-inflammatory cytokines," says Dr. Adise. “Overactivation of pro-inflammatory cytokines can erode the neurons in the brain and cause cell death over time, so we think that both high stress and weight gain may cause neuroinflammation. Prolonged neuroinflammation leads to cell death and changes in the brain structure and function. But neuroinflammation is incredibly hard to see in the brain—so we looked for any structural abnormalities in these regions.”

Did the chicken or egg come first?

The researchers first examined whether financial adversity before and when children were 9 to 10 years old affected the relationship between subcortical development and weight gain. To understand the natural progression of weight gain in these relationships, they also examined MRIs from participants with a healthy weight at the baseline assessment.

Averaging results over two years showed how cumulative exposure to financial adversity could relate to weight gain. “We saw that for youth with higher levels of financial adversity, the smaller volume in these regions was associated with greater BMI change,” says Dr. Adise. “All the kids were at a healthy weight at the start of the study. Maybe about 300 started to creep into unhealthy weight gain. It's good that we're not seeing vast differences in subcortical volume and large weight gains.”

“I think it does give us some hope that perhaps we can intervene and set these children’s brains back on a healthy trajectory,” says Dr. Adise. “Adolescence is when the brain undergoes a lot of changes. So I think it's a critical window in time to focus on—from both a weight gain as well as a neurodevelopmental perspective.”

Reference:

1) https://www.jahonline.org/article/S1054-139X(25)00142-9/fulltext

(Newswise/HRN)

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