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Does High Glucose Affect Memory in Those without Diabetes?

New data point to the negative effects on the brain of high glucose…. 

Previous studies have shown that high levels of glucose can have negative effects on the hippocampus region of the brain which is associated with long and short term memory.

A total of 141 participants from Germany took part in the study. Patients with severe underlying diseases, psychiatric conditions, and type 2 diabetes were excluded. Fasting glucose, HbA1c, and insulin were collected. Using the Rey Auditory Verbal Learning Test, participants were evaluated on delayed recall, learning ability, and memory consolidation. Volume of the hippocampus was also measured using MRI scans.

Scores in all three memory categories were lower when participants had higher HbA1c (long term glucose) and fasting glucose (short term glucose) levels with a p value ≤ 0.01. Insulin had little effect on scores with a p value ≤ 0.07. Multiple regression models found a strong correlation between glucose metabolism and memory performance. A decrease in hippocampal volume has been associated with decreased memory performance. Results from the study show that lower levels of HbA1c meant larger hippocampal volume. Lower fasting glucose levels and higher hippocampal volume were also related but not as great. Insulin and hippocampal volume did not have any correlation to each other. In reference to microstructure, lower levels of all glucose markers (Hb1Ac, FBG, insulin) were associated with lower mean diffusity in the hippocampus which related to improved hippocampal barrier density.

Researchers concluded that even in the absence of type 2 diabetes, high blood glucose can have negative consequences on memory.

Practice Pearls:
  • The hippocampus is a part of the limbic system and is associated with memory. Decreased volume/size of the hippocampus has been associated with impaired memory function.
  • The hippocampus has high vulnerability meaning it may be one of the first targets of the deleterious process set in motion by chronically elevated glucose levels.
  • Lifestyle changes aimed at long-term improvement of glucose control may be a promising strategy to prevent cognitive decline in aging.

Kerti, L. et al. Higher Glucose Levels Associated with Lower Memory and Reduced Hippocampal Microstructure. Neurology 81:1746-1752