By Paul R. Burghardt & Simon J. Evans

In the last article we spoke about the age at which a person develops diabetes increases their risk for different types of dementia. In effect, the longer you can hold-off developing diabetes the less risk you have for developing vascular dementia and Alzheimer’s Disease.

A recent article by De Felice and colleagues in the Proceedings of the National Academy of Sciences speaks to how preventing diabetes or effectively managing the disease can affect brain cells at the microscopic level.

In this study, the researchers were able to show that insulin blocks the protein A-derived diffusible ligand (ADDL). This protein causes all sorts of problems for neurons including withering of the “spines” that make connections with other neurons and redistribution of other neuronal components (receptors) that are critical for the formation of memories.

In a sense, it appears that insulin is helping neurons stick to a microscopic version of the “use it or lose it” principle. When insulin was able to interact (bind to) insulin receptors the ADDL protein was not able to bind to the nerve cells. If you don’t use your insulin receptors, you lose parts of your brain cells (i.e. spines).

One issue that needs to be pointed out regarding this paper is that these studies were carried out in “cell culture.” No, this is not a New-Wave band from the 80’s. Cell culture, in science at lease, refers to a technique used to grow cells in a dish. Once you have cells growing in this very controlled laboratory situation, you can test the effects of different drugs, chemicals, nutrients on various functions of those cells. This is great for learning about how the nuts and bolts of cell biology work, however this is not a “natural” situation for a cell, and it can be difficult to directly use the information gleaned from cell culture experiments in an intact organism (i.e. a walking talking human).

With that cautionary point about cell culture experiments in mind, we’d like to point out that there are studies showing that insulin-sensitizing drugs (drugs that help the body use insulin) can improve memory in diabetics and people with Alzheimer’s Disease. So this is something that people should pay attention to! Not just us nerdy scientists that are fascinated by how things work under a microscope.

The real take-home message for diabetics, relating to the previous blog, is that good management of your diabetes is EXTREMELY important. If insulin has the ability to block these nasty little ADDL proteins from eating the branches of your brain cells, then the better control of your insulin levels should help you fend off these proteins. If you are not diabetic, but have a family history, then take steps to reduce your risk of developing diabetes. This disease occurs over time, so the longer you can avoid it (see the February 17th blog) the less you are likely to accrue.

Now, if you’ve been reading faithfully, you’ll notice Simon focused on the same article in “Control your blood sugar, Improve your memory?” on February 11th, but we wanted to revisit it to tie together with the posted on February 17th, “Diabetes increases risk for developing dementia: what control do you have” to emphasize that no matter if you have ‘normal’ blood glucose control or have diabetes you can help reduce your risk for developing dementia.

Another side-note….although the narrator of the video clip below mentions that insulin does not cross the blood brain barrier (which protects the brain from bad stuff), there is pretty good evidence indicating that insulin actually does cross into the brain.

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