Brain Regions Differ in Children With Prader-Willi Compared to Obese Peers: Study
Size difference with PWS included hypothalamus, which helps control hunger, thirst
Compared to their typically developing peers, children with Prader-Willi syndrome show marked differences in the shapes and sizes of many structures in the brain, including some important for regulating hunger, a new study reports.
Changes seen in patients were not seen in obese children who didn’t have Prader-Willi, indicating these differences are not a secondary result of obesity.
The study, “Alteration of brain nuclei in obese children with and without Prader-Willi syndrome,” was published in Frontiers in Neuroinformatics.
Prader-Willi is a genetic disorder that causes abnormalities in cognitive development and hyperphagia (uncontrolled hunger) that often leads to excessive weight gain. These behavioral and cognitive abnormalities presumably arise due to differences in how the brain develops.
While some studies have investigated how brain structures are altered with Prader-Willi, these changes (and their effects on behavior and development) aren’t completely understood. Complicating matters, obesity itself has been associated with alterations in the brain, which can make it hard to tease out what changes are due to the genetic disorder and which stem from obesity.
A trio of scientists in China analyzed brain images of 12 children with Prader-Willi — eight girls and four boys (mean age, 7.2). For comparison, they also looked at images for two control groups without Prader-Willi: one of 18 children who were clinically obese and a group of 18 who weren’t. The analysis focused specifically on brain nuclei, clusters of nerve cells with related functions.
Results showed no significant differences in brain structure between the two control groups.
In children with Prader-Willi syndrome, the size of several brain regions was significantly reduced. Among the affected brain regions were the amygdala, which is important for processing emotions; the thalamus, which is involved in processing sensory signals; and the hippocampus, critical for memory.
Size reductions were also noted in the hypothalamus, which helps regulate systems that aren’t under conscious control, such as sleep and body temperature. The hypothalamus is also important for controlling hunger and thirst. Reductions in the size of the nucleus accumbens, another region important for feeding, were also reported in Prader-Willi patients.
Since these alterations were found in children with Prader-Willi, but not those who didn’t have the disease, this indicates brain nuclei alterations “might be associated with eating disorders, cognitive disability, and endocrine [hormone-related] abnormalities that mark” the genetic disorder, the researchers noted. And the changes are likely attributable to Prader-Willi and not to secondary effects of obesity on the brain’s development, since they weren’t present even in obese controls.
“Our results suggest that although PWS and obesity share predominant clinical manifestations (e.g., overweight and hyperphagia) … impairment in brain nuclei may be very different,” the investigators wrote, noting their study was limited by its small size, as well as technical constraints in measuring brain regions, underscoring a need for more research to learn how Prader-Willi alters the brain. “In the future, the relationship between genetic subtypes and structural change could be investigated to examine the influence of heritable differences involving PWS on brain nuclei.”
About the Author
