Youth Obesity and the Nucleus Accumbens

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In the past decade, the prevalence of obesity in children and adolescents has significantly increased from 4% in 1975 to over 18% globally today, affecting up to 35% of youth in the United States. Obesity is associated with poor mental health and higher mortality rates. Therefore, it has become increasingly urgent to develop a technique to tackle this problem.

A recent study funded by institutes from the National Institute of Health provides promising results towards finding a way to predict obesity in children and adolescents.

Researchers analysed a set of data collected from over 11’000 children (aged 9 to 10) using a highly specialised brain-imaging technique to analyse cell density in the Nucleus Accumbens (NAcc). Their aim was to compare waist circumference and cell density to determine whether there is a correlation between the two.

Obesity has previously been quantified using body mass index (BMI), however, recent guidelines have suggested that waist circumference may be a better estimate in children.

The NAcc is a region of the brain best known as part of the reward system, its roles involve two essential neurotransmitters: dopamine, which promotes desire, and serotonin, whose effects include satiety and inhibition. Recent research on the NAcc has suggested it has a role in promoting unhealthy eating and other reward-motivated behaviours in adults when there is a greater concentration of specialised cells in the region – an inflammatory response.

Nucleus Accumbens. Wikipedia, 2020.

The findings confirmed the correlation. The greater concentration of cells in the NAcc, the larger the waist circumference of the child. Even more surprisingly, it was also found that the neuroinflammation could also predict the child’s future weight gain in a follow-up study a year after.

Previous studies in animals had shown that a diet high in saturated fats spurs neuroinflammation in the brain which increases the number of cells in the nucleus accumbens. This accumulation often triggers compulsive eating in animals.

It is discussed that the relationship found might be explained by the fact that the NAcc has a role in motivating eating behaviour, therefore, a higher cell density will signify an increase in unhealthy eating which will eventually result in an increase in waist circumference.

The researchers labelled this a ‘vicious cycle’ where eating unhealthy food leads to a craving for more unhealthy food. The results provide a basis for future interventions to tackle this increasingly prevalent issue. This can inform prevention strategies and promote early interventions.

Original source: Rapuano, K., Laurent, J., Hagler, D., Hatton, S., Thompson, W., Jernigan, T., Dale, A., Casey, B. and Watts, R., 2020. Nucleus accumbens cytoarchitecture predicts weight gain in children. Proceedings of the National Academy of Sciences, p.202007918. https://doi.org/10.1073/pnas.2007918117

Image source: Science Daily, 2017

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