According to a study presented at the annual meeting of the Radiological Society of North America (RSNA) obesity has been found to trigger inflammation in the nervous system.
Obesity in young people has become a significant public health problem. In the U.S., the percentage of children and adolescents affected by obesity has more than tripled since the 1970s, according to the Centres for Disease Control and Prevention. Data from the World Health Organization indicates that the number of overweight or obese infants and young children ages five years or younger increased from 32 million globally in 1990 to 41 million in 2016.
While obesity has been associated with chronic diseases and conditions such as heart disease and hypertension, evidence suggest that obesity can trigger inflammation in the nervous system that could result in damage to vital regions of the brain. Developments in MRI like diffusion tensor imaging (DTI), a technique that tracks the diffusion of water along the brain’s signal-carrying white matter tracts, have enabled researchers to study this damage directly.
The study involved the comparison of DTI results in 59 obese adolescents and 61 healthy adolescents, from 12 to 16 years of age. Based on the DTI, the researchers derived a measure called fractional anisotrophy (FA), which correlates with the condition of the brain’s white matter. The lower the FA indicates increasing damage in the white matter.
The results showed a reduction of FA values in the obese adolescents in regions located in the corpus callosum, a bundle of nerve fibres that connects the left and right hemispheres of the brain. Decrease of FA was also found in the middle orbitofrontal gyrus, a brain region related to emotional control and the reward circuit. None of the brain regions in obese patients showed an increased FA.
“Brain changes found in obese adolescents related to important regions responsible for control of appetite, emotions and cognitive functions,” said study co-author Pamela Bertolazzi, a biomedical scientist and Ph.D. student from the University of São Paulo in Brazil.
This pattern of damage correlated with some inflammatory markers like leptin, a hormone made by fat cells that helps regulate energy levels and fat stores. In some obese people, the brain does not respond to leptin, causing them to keep eating despite adequate or excessive fat stores. This condition, known as leptin resistance, makes the fat cells produce even more leptin.
Worsening condition of the white matter was also associated with levels of insulin, a hormone produced in the pancreas that helps regulate blood sugar levels. Obese people often suffer from insulin resistance, a state in which the body is resistant to the effects of the hormone.
Dr. Bertolazzi also highlighted that further studies are required to decide conclusively if the inflammation is a result of structural changes in adolescent brains. [APBN]