At first blush, it may be hard to imagine a connection between type 2 diabetes and Alzheimer’s disease or other forms of dementia. But it’s real—and it’s so strong that some experts are now referring to it as type 3 diabetes or brain diabetes. By any name, it’s the progression from type 2 diabetes to Alzheimer’s disease and other forms of dementia marked by memory deficits and a dramatic decline in cognitive function.
While all people with diabetes have a 60 percent increased risk of developing any type of dementia, including Alzheimer’s, recent research suggests that women with type 2 diabetes have a 19 percent greater risk of a certain type, known as vascular dementia (which is caused by problems with blood supply to the brain) than men do. Overall, older adults with type 2 diabetes suffer from greater declines in working memory and executive functioning (a set of mental processes that involve planning, organization, controlling attention, and flexible thinking) than their peers do.
Granted, not everyone who has type 2 diabetes will develop Alzheimer’s disease, vascular dementia, or any other form of dementia, and there are many people who have Alzheimer’s or another form of dementia who don’t have diabetes, notes Gary Small, M.D., a professor of psychiatry at the UCLA Semel Institute and author of The Alzheimer’s Prevention Program. But the reality is, “these risk factors tend to add up: If you have diabetes, that doubles the risk of developing Alzheimer’s. If you have a first-degree relative—a parent or sibling, for example—with Alzheimer’s, that doubles your risk.” And if you have poorly controlled blood pressure, abdominal (a.k.a., central) obesity, or sleep apnea, your risk of developing dementia is increased even more.
Surprisingly Harmful Ripple Effects
As far as how type 2 diabetes increases the risk of dementia—well, it’s complicated. For starters, high blood sugar leads to inflammation throughout your body and brain. With respect to Alzheimer’s, this is a problem because chronic inflammation has been linked with the formation of amyloid plaques and tau tangles, abnormalities in the brain that are hallmarks of Alzheimer’s disease, Dr. Small explains.
In addition, insulin resistance (the hallmark of type 2 diabetes) can impair blood flow to the brain, which means brain cells aren’t getting sufficient oxygen and nutrients for them to function properly. And then there’s the added problem of insulin insensitivity in the brain—simply put, just as insulin resistance plays out in the rest of the body, when there’s impaired insulin signaling in the brain, brain cells can’t use glucose (their primary energy source) properly, and brain function suffers as a result. In case that isn’t worrisome enough, “when circulation to the brain is compromised, you’re more prone to developing small strokes [that can increase the risk of dementia],” Dr. Small says.
Meanwhile, type 2 diabetes can cause toxic proteins to accumulate in the brain and it may impair the brain’s ability to clear out waste products, too, explains Suzanne Craft, Ph.D., professor of medicine and director of the Alzheimer’s Disease Core Center at the Wake Forest School of Medicine in Winston-Salem, North Carolina. Moreover, “type 2 diabetes may [compromise] … important brain functions such as the formation and maintenance of new connections between brain cells.” Any way you slice it, the combination of these signaling, cellular, and functional changes adds up to a vastly increased vulnerability to cognitive impairment as you get older.
Protecting Your Brain Matter
While this all may sound alarming, there’s good news: Half of a person’s risk of developing Alzheimer’s is attributable to factors you can change, such as diet and physical activity, Dr. Small says. Taking steps to control your diabetes with medication and lifestyle changes may help reduce your risk of developing any form of cognitive impairment. So consider this yet another wake-up call to take steps now to protect your brain and your body from the harmful effects of diabetes. Here’s how:
Exercise regularly. You’ll gain a double dose of benefits for diabetes control and your brain, Craft says. Specifically, aerobic exercise boosts circulation throughout the body and the brain and helps your body use insulin better; meanwhile, strength-training workouts can enhance insulin sensitivity and lower your blood sugar. That’s why the American Diabetes Association recommends doing 30 minutes of moderate-to-vigorous intensity exercise at least five times per week and strength training at least twice per week.
Eat a healthy diet. That means one that’s “low in processed foods and added sugars and rich in whole foods,” Craft advises. Remember, too: Certain spices (such as turmeric and cinnamon) and aromatic herbs (such as oregano) have anti-inflammatory and/or blood-sugar-lowering effects.
Manage your body weight. In particular, “central obesity—fat around the abdominal organs—is pro-inflammatory,” Dr. Small notes. Besides being a risk factor for the development of type 2 diabetes, abdominal obesity increases your risk of heart disease and impairs brain health, increasing the risk for Alzheimer’s disease, he adds. Consider this added incentive to get your weight into a healthy range (a body mass index under 25) and your waist circumference under 35 inches if you’re a woman, under 40 inches if you’re a man.
Maintain tight blood sugar control. Follow your doctor’s advice for taking any diabetes medications and monitoring your blood sugar. Doing so may reduce your risk of developing dementia as well as other complications from diabetes. “Insulin used to treat diabetes may protect the brain from toxic amyloid proteins that damage brain cell connections,” Dr. Small says, while other drugs used to treat type 2 diabetes “increase sensitivity to insulin and enhance its brain protective effects.”
To keep your mind sharp, it’s also wise to get plenty of good quality sleep and to manage stress. (Mindfulness meditation can be especially helpful for relieving stress, improving mental focus, and fortifying neuronal connections, Dr. Small says.) It also helps to train your brain with the right forms of stimulation, whether you want to learn a new skill (piano or chess, anyone?), read challenging books, or play word games, math games, computer games, or trivia games.
Ultimately, “it’s easier to protect a healthy brain than to try to repair damage once it’s extensive,” Dr. Small says. “And what you do to help your brain also helps your body.” That’s a double payoff, if ever there was one.
Stacey Colino is an award-winning writer, specializing in health and psychology, based in Chevy Chase, Maryland. She has written several books including Disease-Proof: The Remarkable Truth About What Makes Us Well, with Dr. David Katz.
Disclaimer: The statements on this page represent the views of the UCLA Semel Institute for Neuroscience and Human Behavior and do not necessarily represent the views of the University of California, or UCLA or its Chancellor.