Higher Blood Glucose Leads to Change in Brain Structure

Chronically high blood glucose levels in older adults were associated with performance on cognitive tests, as well as structural changes to learning-relevant hippocampus section of the brain.

Agnes Floel, MD, of Charite-University Medicine in Berlin, and colleagues, analyzed data from 141 adults, 50 to 80 years old, with body mass index value of 25 to 30. Mean glycated hemoglobin (HbA1c) levels were 5.8%, mean age was 63-years-old.

Researchers conducted blood sampling, brain MRI scans, and the Rey Auditory Verbal Learning Test, searching for associations between HbA1c levels and cognitive performance.

They found that for each standard deviation increase in HbA1c, a decrease of 0.18 to 0.27 standard deviations (Delayed recall: -0.27, Learning ability: -0.22, Memory consolidation: -0.18) occurred in learning ability, memory, and delayed recall.

They also observed decreases in hippocampal volume in participants with heightened HbA1c levels. “Even in the absence of manifest type 2 diabetes mellitus or impaired glucose tolerance, chronically higher blood glucose levels exert a negative influence on cognition, possibly mediated by structural changes in learning-relevant brain areas,” researchers concluded.

“Therefore, strategies aimed at lowering glucose levels even in the normal range may beneficially influence cognition in the older population, a hypothesis to be examined in future interventional trials.”

–Michael Potts

Reference:

Floel A, Kerti L, Witte V, Winkler A, et al. Higher glucose levels associated with lower memory and reduced hippocampal microstructure [Published online before print October 23, 2013] Neurology doi: 10.1212/01.wnl.0000435561.00234.ee