What's the story about diabetes, cholesterol and your brain?

Diabetes is a recognised risk factor for dementia. It is also associated with a higher risk of depression and eating disorders. What has now been found is that diabetes affects how much cholesterol our brain can make.

That’s right, our brain makes it’s own cholesterol that it uses to form synapses (the connections between brain cells). It is also used to form the vesicles or storage structures located at the synapse that contain the neurotransmitters, the brain’s chemicals that are passed from one brain cell to the next. We have a “fat” head and it is essential the brain can produce sufficient cholesterol for healthy brain function. Having too little cholesterol in the brain is associated with Alzheimer’s disease and other neurodegenerative conditions.

Studies using mice with type 1 (insulin deficient) diabetes looked at gene expression in an area of the brain called the hypothalamus. It was found that in these mice, gene expression for the synthesis of cholesterol was reduced. Treating them using insulin reversed the problem. They also found that those mice with unable to synthesise brain cholesterol gained more weight and ate more, indicating that diabetes may affect those brain hormones associated with appetite regulation.

This finding adds to our understanding of the relationship between diabetes, cholesterol and healthy brain function. If you have diabetes, having tight glycaemic (sugar) control and maintaining a healthy weight are essential to help your overall brain health and to protect against future cognitive decline.

Ryo Suzuki, Kevin Lee, Enxuan Jing, Sudha B. Biddinger, Jeffrey G. McDonald, Thomas J. Montine, Suzanne Craft, C. Ronald Kahn. Diabetes and Insulin in Regulation of Brain Cholesterol Metabolism. Cell Metabolism, Volume 12, Issue 6, 567-579, 1 December 2010 DOI: 10.1016/j.cmet.2010.11.006