Brain Abnormalities Seen in Children with Severe Form of Diabetes

Children with a rare syndrome that includes a form of insulin-dependent diabetes have brain abnormalities that appear to create cognitive problems later in life, according to new imaging research.

The scientists, from Washington University School of Medicine in St. Louis (MO, USA), examined children with Wolfram syndrome, which causes insulin-dependent diabetes in childhood. The disorder also causes hearing and vision loss and kidney difficulties. As patients get older, they can develop cognitive difficulties and dementia, and more than half die before their 30th birthday. Earlier case studies had used imaging to identify brain abnormalities, but doctors had assumed those changes occurred late in the disease process when Wolfram’s patients got older. The new findings suggest, however, that some alterations in the brain occur early in childhood.

The study’s findings were published in the online July 11, 2012, in the journal Public Library of Science (PLoS) One. “This work strongly suggests that brain changes occur very early in the disease,” said first author Tamara Hershey, PhD. “The Wolfram gene is important throughout the body--in the heart, retina, pancreas, and so on. The pancreas is affected very early in development eventually leading to diabetes, so it stands to reason that other organs like the brain may also be affected at an early age, even before a child experiences any cognitive problems.”

Wolfram syndrome results from mutations in a single gene called WSF-1, which was first identified in 1998 by the late M. Alan Permutt, MD, a former professor of medicine and of cell biology and physiology. He later developed an animal model of the disorder. In 2010, Dr. Permutt organized the world’s first clinic exclusively for patients with Wolfram syndrome. The initiative gathered children worldwide to St. Louis for testing and assessment. Another clinic was held in 2011, and a third will take place this summer at St. Louis Children’s Hospital.

Dr. Hershey, a professor of psychiatry, of neurology and of radiology, centered on the neurologic features of Wolfram syndrome. She leads the scientific efforts of the interdisciplinary clinic, along with Bess A. Marshall, MD, associate professor of pediatrics, who is the clinic’s medical director. Almost a dozen Washington University faculty members evaluate patients at the Wolfram clinic as part of studies to better understand the syndrome.

For the new study, Dr. Hershey obtained brain scans of Wolfram patients ages 5-25 and other young patients who only had type 1 diabetes, along with healthy controls in the same age range. The study represents the first time that scientists have attempted to measure and statistically quantify brain differences in patients with Wolfram syndrome. “These individuals are intact cognitively, and some of them are very smart, high-functioning kids,” she noted. “But we have been able to detect significant differences in the size of certain brain structures, leading us to believe that some of these differences must happen during brain development.”

In particular, Dr. Hershey’s group has identified alteration in the brainstem and the cerebellum. They also discovered that the skulls of these children tended to be smaller than would have been expected, based on their ages at the time of the study. The investigators also identified differences in the thickness of the brain’s cortex, in particular, in parts of the cortex related to vision. “We were able to pinpoint those regions of the brain that are most affected in terms of size--the brainstem and the cerebellum,” she stated. “And we also used a type of imaging called diffusion tensor imaging [DTI] that allowed us to measure the integrity of white matter pathways in the brain. Again, we found evidence that the brainstem and the cerebellum white matter were affected in patients with Wolfram syndrome, compared to those with type 1 diabetes only and healthy controls.”

DTI employs magnetic resonance imaging (MRI) to map the brain’s white matter tracts and perform fiber tracking. Wolfram syndrome is very rare, affecting an estimated one in 770,000 children. Before these comprehensive research clinics were established, most of what scientists knew about the brains of patients with the disorder had come from clinical exams of adult patients or autopsies of patients with Wolfram’s.

Dr. Hershey believes that by conducting annual MRI scans and continuing to track patients with Wolfram syndrome over time, it may be possible to distinguish changes that occur during brain development from those that occur due to degeneration related to the disorder.

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Washington University School of Medicine in St. Louis