Less Brain Gray-Matter Volume in Youth With Type 2 Diabetes

Marlene Busko

June 21, 2016

NEW ORLEANS — Twenty obese 10- to 20-year-olds with recently diagnosed type 2 diabetes had significantly smaller brain gray-matter volumes than 20 lean, nondiabetic controls of the same age, race, and gender, in a new study.

Although the study wasn't powered to detect neurocognitive differences, it did find that the children and youths with type 2 diabetes had lower Woodcock-Johnson word attack scores — that is, they had worse phonetic skills when reading nonsense words aloud.

Jacob M Redel, MD, a clinical fellow at Cincinnati Children's Hospital, Ohio, presented the study on June 14 at the President's Oral Session here at the American Diabetes Association (ADA) 2016 Scientific Sessions. "Whether these findings explain poorer cognitive scores observed previously remains to be determined," he and his group say in their abstract.

"It does imply that something happens to the brain in people with diabetes — very early in exposure and even in children," Elizabeth R Seaquist, MD, University of Minnesota School of Medicine, Minneapolis, told Medscape Medical News. "They clearly need to do a comparison with an obese group of children because obesity has its own effects on the brain, but it tells us again that diabetes isn't good for the brain."

Other studies have examined brain development in children with type 1 diabetes, "but this is really the first in type 2 children," Dr Seaquist said. Moreover, brain development is a slow, lengthy process that can be altered by many things. "Correlating [brain development] to cognitive changes over time is going to be important," and a larger study might shed more light on other measures of cognition, she added.

The sample was small, and therefore these interesting findings need to be interpreted with caution, Desmond Schatz, MD, session comoderator and president, medicine and science, of the American Diabetes Association, and professor of pediatrics, University of Florida, Gainesville, echoed, in a comment to Medscape Medical News. Follow-up study should also look at gray-matter volume in the parents and siblings of these young diabetic patients, he suggested.

In the meantime, this study hints at "some really disturbing consequences of early appearance of diabetes and the aggressive nature of the disease," he said. "I certainly think we need to monitor this because if there's a way to intervene it's absolutely critical," Dr Schatz summarized.

Type 2 Diabetes and Brain Development in Children

Previous studies have shown that compared with their peers, youth with type 2 diabetes have worse cognitive-function test scores, but there has not been a comprehensive assessment of total and regional brain gray-matter volume in this patient population, according to Dr Redel.

To investigate this, the researchers enrolled 20 obese patients with diagnosed type 2 diabetes and matched them with healthy controls.

The participants had a mean age of 16.7 years, and the diabetic patients had a higher mean body mass index (BMI) than the control patients (37.5 vs 24.5). On average, the patients with diabetes had a mean HbA1c of 7.9% when they were diagnosed with diabetes 2.8 years ago.

MRI scans revealed that, compared with controls, the youth with type 2 diabetes had less total gray-matter volume (717 cm2 vs 656 cm2 ; P = .012) but similar white-matter and total brain volumes.

To account for different brain sizes in children and youth of the same age, race, and sex, the researchers calculated "adjusted gray-matter volume" (gray-matter volume divided by total volume); this measure too ""was still significantly lower in the diabetic patients (P = .02).

Having a lower volume of brain gray matter predicted a lower word-attack score (P = .043).

The researchers plan to do a follow-up study in a larger group of subjects, with obese, nondiabetic control patients, said Dr Redel.

Dr Redel and colleagues have no relevant financial relationships. Dr Seaquist is a former president of the American Diabetes Association and has consulted for Sanofi, Medtronic, Locemia Solutions, and Novo Nordisk. She has been on speakers' bureaus for Locemia Solutions and Novo Nordisk and has received research grants from Eli Lilly and the National Institutes of Health. Dr Schatz has no relevant financial relationships.

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American Diabetes Association 2016 Scientific Sessions; June 14, 2016; New Orleans, Louisiana. Abstract 376-OR

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