Keeping Your Brain Strong With Diabetes

Diabetes has powerful effects on the brain. Chronically high blood sugar seems to reduce brain function for many people. How do you protect your brain from diabetes’ effects?

We know that insulin is crucial to a healthy central nervous system (or CNS, the brain and spinal cord). Insulin works differently in the brain than in the rest of the body. Scientists in Seattle found that most of insulin’s effects on how we think and eat come through “CNS mechanisms” other than glucose uptake.


When blood glucose levels are high, insulin has trouble getting into the brain. The molecules that transport it across the “blood-brain barrier” are affected by diabetes or by high sugars. This is called “CNS insulin resistance.”

William Klein, PhD, professor of neurology at Northwestern University, says that, “Insulin seems to play a role in learning and memory.” If insulin can’t do its job in the brain, learning and memory are compromised. This process can lead to Alzheimer disease according to Erika Gebel, PhD.

Studies show that both Alzheimer disease and “vascular dementia” are more common in people with Type 2 diabetes. People with poorly controlled Type 1 diabetes may also be at risk, according to an article in the journal Diabetes.

“Vascular dementia” means brain damage caused by blood vessel damage. Alzheimer dementia is a disease where proteins called beta-amyloids attach to nerve cells and appear to block insulin from working. This is why Alzheimer has been called “Type 3 diabetes.”

The effects can be seen in memory loss, poorer decision-making, and loss of focus. It’s a sneaky complication. You’re not likely to notice it for a long time, although other people might.

Improving your brain
This is all pretty scary news, but diabetes brain symptoms can be prevented and often reversed. Three main strategies seem to work.

• Physical exercise. According to the National Institute on Aging (NIA), “Physical exercise may play a role in reducing risk for Alzheimer disease and age-related cognitive decline.”

According to NIA, rat and mouse studies have found that exercise grows new blood vessels that supply blood to the brain. It also causes nerve cells to make more connections. So brain shrinkage may be stopped with exercise!

Human studies have found that people who walked regularly had better memory and better ability to plan ahead than people who did nonaerobic exercises such as stretching.

• Mental exercise. Brains can get smarter, but you have to exercise them, too. NIA says we have to stay “cognitively active” throughout life. (“Cognition” means thinking.) We can do this through social engagement or through brain activities.

“Social engagement” includes volunteering, working, living, or hanging out with other people. “Activities such as reading books and magazines, going to lectures, and playing games are also linked to keeping the mind sharp,” according to NIA.

What kind of brain exercise?
Brain exercises, often called “cognitive training,” are all the rage on the Internet now. They work, at least to a degree. In a study called ACTIVE, healthy adults 65 and older participated in 10 sessions of training for memory and thinking fast. “The sessions improved participants’ mental skills in the area in which they were trained. These improvements persisted 10 years after the training was complete.”

My mother was one of the early subjects in the studies that led to popular programs such as Lumosity and Dakim BrainFitness. The programs worked her hard, but the results were great, and she continues to use them. She is now 91 years old and probably thinks faster and better than I do.

According to The New York Times, a study by researchers at the University of California, San Francisco, showed “a [computerized] driving game did improve short-term memory and long-term focus in older adults.”

Dr. Murali Doraiswamy of the Duke Institute for Brain Sciences believes that people probably don’t need “a $300 subscription to a gaming company.” (Actual prices are more like $6 to $10 a month.)

He said doing challenging things on your own, like attending a lecture or learning an instrument, would probably have the same benefits. “Each person has to personalize for themselves what they find fun and challenging and what they can stick with.”

In brain training, it’s better not to do the same thing over and over. Mental activities like chess and sudoku are good for you, but if that’s all you do, it becomes more habit than thinking. Mental activities that do some good for you or for other people in the real world may be better than games. But all mental activity helps. I hope researching and writing these articles every week is helping me.

• Diet. Our nutritionist Amy Campbell wrote here that fatty fish, omega-3 oils, cruciferous vegetables (such as broccoli, cabbage, and kale), blueberries, walnuts, leafy greens (such as collards or mustard greens), and Concord grape juice have all shown benefits for brain health. Supplements such as vitamins C and E, the herb gingko biloba, acetyl-l-carnitine, and others may also be good for your brain.

Of course, any strategy that improves glucose control is also likely to help insulin get into the brain and stop diabetes-related dementia. Inhaled insulin may one day be a treatment for Alzheimer, even in people without diabetes.

Conclusion: If you keep your body and brain active and control your glucose, you can stay smart.