Gray matter differences imaged in diabetic teens

Prior research has established that teenagers with type 2 diabetes have different gray matter volumes and poorer cognitive function than their nondiabetic peers. A new MRI-based study at Cincinnati Children's Hospital Medical Center has imaged the particular regions in which the differences occur.

Lead author Jacob Redel, MD, presented the team’s findings June 14 at the annual scientific sessions of the American Diabetes Association in New Orleans.

The researchers examined total and regional brain gray matter volumes in 20 teens with type 2 diabetes mellitus (T2DM), most of whom had the condition for a relatively short duration (average 2.8 years from diagnosis).

They compared these observations with brain MR images from 20 healthy control participants matched for race, sex and age.

None of the subjects in either group had evidence of neuropsychological disease or prior abnormal MRI.

The team made comparisons using high-resolution T1-weighted structural MRI scans and voxel-based morphometry analysis, according to the study abstract.

Compared to members of the control group, the T2DM cohort had decreased total gray matter volume (717±74 vs. 656 ±71).

Specifically, the T2DM youth had 10 regions—within the temporal lobe, occipital lobe, parietal lobe, cingulate gyrus and basal ganglia—with significantly less gray matter volume than their peers in the control group.

Perhaps surprisingly, the T2DM group also had five regions—within the frontal lobe and basal ganglia—with significantly greater gray matter volume than controls.

This part of the brain is known to regulate or control voluntary motor movements, procedural learning, habits, cognition and emotion.

“Youth with short duration of T2DM show significant differences in gray matter volume,” the authors conclude in their abstract. “Whether these findings explain poorer cognitive scores observed previously remains to be determined.”

In a press release, Cincinnati Children’s says the researchers further noted a relationship between less gray matter volume in the brain and the ability to pronounce and sound out unfamiliar words.

“Our results do not show cause and effect,” Redel states in the release. “We don't know if the changes we found are the direct result of diabetes, but studies in adults with type 2 diabetes with longer duration of disease also show brain volume differences, brain vascular changes and cognitive decline.”

Redel adds that the new findings support the consensus that preventing type 2 diabetes in adolescents can ward off complications with cognitive function later in life.

Cincinnati Children’s says the researchers are considering setting up a larger study, one that would add participants who are obese but without type 2 diabetes.

“This would allow them to examine whether differences found on MRI are more related to obesity or high blood sugar seen in diabetes,” according to the institution, “and test whether other cognitive domains, such as memory, language, intellect and attention, are affected by brain volume differences.”