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Deficits in grey brain matter found in children with congenital hypothyroidism
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American Thyroid Association's 80th Annual Meeting
Early thyroid hormone deficiency in children with congenital hypothyroidism was associated with reductions in grey brain matter density, according to data presented at the American Thyroid Association 80th Annual Meeting.
“Reductions in brain matter density are associated with later compromised cognitive functioning,” Joanne Rovet, PhD, senior scientist in the neuroscience and mental health program at The Hospital for Sick Children in Toronto, said during the meeting.
Previous research has suggested an association between hippocampal atrophy and congenital hypothyroidism, so Rovet and colleagues set out to asses whether other conditions may possibly be affected.
The study included 15 children with congenital hypothyroidism and 21 controls aged 10 to 16 years. Children underwent neuroimaging, and T1-weighted images were assessed with voxel-based morphometry.
"Data indicated that congenital hypothyroidism showed 11 regions of reduced grey matter relative to controls and no meaningful cluster involving more grey matter than controls," Rovet told Endocrine Today.
Compared with the control group, voxel-based morphometry identified two voxel clusters >30,000 in each frontal lobe in the group of children with congenital hypothyroidism. In addition, more grey matter was found in the bilateral hippocampus, in multiple regions of visual pathways and bilateral amygdala and putamen in children with congenital hypothyroidism.
“In congenital hypothyroidism, neurogenesis is reduced in brain regions subserving cognitive abilities on which these children consistently show difficulty,” Rovet said. “This effect likely reflects their lack of thyroid hormone from onset of disease until euthyroidism is achieved following early treatment.”
Rovet concluded that “the large frontal clusters observed may signify disrupted functioning of larger systems compared with localized frontal deficits. Additionally, these system deficits may be contributing to observed visuospatial and memory deficits.” - by Jennifer Southall
For more information:
- Rovet J. Oral #9. Presented at: The American Thyroid Association’s 80th Annual Meeting; Sept. 23-27, 2009; Palm Beach, Fla.
Read more from the ATA's 80th Annual Meeting>>
The screening and prompt treatment of infants with congenital hypothyroidism is one of the great successes in endocrinology. Children who receive timely and adequate thyroxine treatment have normal, or nearly normal, intellectual function as assessed by standard intelligence tests. In a series of studies using more sophisticated tools to assess sensory and cognitive processing, Rovet and colleagues have identified more subtle functional deficits in individuals with treated congenital hypothyroidism. The current study uses brain imaging to show reduced grey matter in brain areas corresponding to identified functional deficits in visuospatial processing and memory. These findings are important in our understanding of thyroid hormone action in human brain development. Individuals with treated congenital hypothyroidism, however, are a heterogenous group with respect to variability in: endogenous thyroid hormone production, maternal thyroid function and iodine intake during pregnancy, time interval from diagnosis to T4 treatment, T4 dose utilized and adherence to treatment. Understanding the relative importance of these factors will be important in translating these findings to clinical practice.
– Gregory Brent, MD
Endocrine Today Editorial Board member
