Memory Performance: Negatively Impacted by Higher Glucose, even in Non-Diabetics Interview with:
Lucia Kerti MA
From the Departments of Neurology
Charité–University Medicine, Berlin What are the main findings of the study?

Answer: The results of our study on 141 healthy older people suggest that chronically higher blood glucose levels may have a negative influence on memory performance even in the absence of type 2 diabetes or even pre-diabetes. Moreover, our findings indicate that elevated blood glucose levels impair the functioning of brain areas like the hippocampus, a structure particularly relevant for memory. An important novel aspect in our study was the additional analysis of diffusion tensor imaging-based mean diffusivity within the hippocampal, which allowed us to obtain information on microstructure. We here provided first-time data of an association between higher blood glucose levels and lower hippocampal microstructure. Decreased hippocampal microstructure as measured by mean diffusivity may reflect a disruption of neuronal membranes and increased extracellular water content, leading to decreased signaling within and between hippocampal cells. Thus, information transfer between cells, indispensable for memory encoding, storage and retrieval, would be compromised. In sum, our data suggest that chronically higher blood glucose levels even within the “normal range” may decrease memory functions, possibly in part mediated by microstructural changes within the hippocampus. Were any of the findings unexpected?

Answer: Our findings were in line with previous studies that were able to demonstrate associations between non diabetic glucose levels and memory performance and hippocampal volume. Yet, we here provided first-time results showing not only an association between higher glucose levels and poorer memory performance, but also a partial mediation of these effects by hippocampal volume and microstructure. What should clinicians and patients take away from your report?

Answer: As a general recommendation, several lifestyle choices tend to lower blood glucose levels in young and old individuals. These include avoidance of obesity (particularly in mid-life), consuming a diet rich in fibers, vegetables, fruit, fish, and whole-grain products (sometimes referred to as “Mediterranean foods”), and undertaking physical activity on a regular basis. Moreover, in individuals at risk – e. g., those presenting with obesity -, and in everyone from age 55 onwards, regular health checks at the primary care physician should include fasting glucose and HbA1c levels for early detection and treatment of elevated glucose levels. What recommendations do you have for future research as a result of this study?

Answer: Future interventional trials should elucidate whether specific lifestyle changes aimed at long-term improvement of glucose control actually prevent cognitive decline in aging. One strategy to be assessed would be lower dietary caloric intake, or dietary supplementation that “mimic” the effects of caloric restriction. Another important strategy would be to regular physical activity. Smaller interventional trials are currently running at our site and others around the world, but larger international collaborative initiatives will be needed as well.


Higher glucose levels associated with lower memory and reduced hippocampal microstructure

Lucia Kerti, A. Veronica Witte, Angela Winkler, Ulrike Grittner, Dan Rujescu, and Agnes Flöel

Article | Neurology 10.1212/; published ahead of print October 23, 2013