Having diabetes can put you at greater risk for heart disease, kidney failure, blindness and nerve damage. Can it put you at higher risk for dementia, too?
“The connection is definitely there, but it’s tenuous. There are a lot of theories about how it might happen, but not a lot of proof,” says John Buse, MD, PhD, director of the UNC Diabetes Care Center and chief of the Division of Endocrinology and Metabolism.
Dr. Buse helped explain some of the possible explanations for how diabetes and dementia might be linked.
1. Diabetes can damage the heart and blood vessels, which can impact the brain.
People with type 2 diabetes tend to have high blood pressure and higher levels of triglycerides, or fat, in the blood. This puts them at higher risk of blood vessel damage and inadequate blood flow to their tissues, Dr. Buse says. “Triglycerides are associated with lower levels of the good cholesterol and more particles of bad cholesterol circulating in the blood. These bad cholesterol particles damage blood vessels,” he says.
The high blood pressure and cholesterol problems impact the blood vessels in two ways: They can narrow the arteries and lead to stroke, or they can damage the body’s tiny blood vessels, leading to poor availability of oxygen and nutrients.
These complications of diabetes are often associated with heart disease and stroke, among other conditions. “Sometimes this mixture of high blood sugar, high blood pressure and cholesterol abnormalities associated with high triglycerides is referred together as cardiometabolic risk,” Dr. Buse says. “That is, diabetes comes with certain baggage, part of which is the high blood sugar, but it’s also these other processes that lead to the complications of diabetes.”
The damage done to the blood vessels as a result might contribute to dementia. “It’s a very broad explanation for dementia, but it could certainly drive higher risks,” Dr. Buse says.
2. Blood sugar and metabolic processes create changes in the brain that lead to dementia.
“A second classical explanation is particularly an issue in type 1 diabetes, and that is problems with recurrent episodes of hypoglycemia, or low blood sugar,” Dr. Buse says. Although research has not shown a definitive link between blood sugar and dementia, Dr. Buse says it is something to worry about. “Certainly, every diabetes doctor in the field has had a patient who had a low blood sugar event and was really not quite the same cognitively afterward. For individuals who have had low blood sugar for a long period of time, it does seem to damage the brain in a permanent way, though this might be a case that a diabetes doctor sees only every few years.”
3. Stress plays a role in both diabetes and dementia.
Dr. Buse says that because both dementia and diabetes cause physiological stress on the body, this could link the two conditions. “Clearly, stress is associated with a higher risk of diabetes as well as worse cognitive outcomes,” he says. “Whether it’s the impact of stress hormones such as adrenaline or cortisol on the body that causes a higher risk or if stress is just another interrelated factor, we don’t know.”
4. It’s inherently a mutual connection.
People with diabetes have a higher risk of dementia and chronic mental illnesses, such as schizophrenia and major depressive disorder, while people with dementia and mental illnesses also have a high risk of diabetes. “We do wonder a bit about whether it’s a bidirectional process; that is, we don’t know if one causes the other or if they feed on each other,” Dr. Buse says.
There’s also a possibility that medications play a role. “Many of the drugs that we use to manage chronic mental illness have clear impacts on metabolism and worsen diabetes control, but we generally do not think of diabetes drugs causing mental illness,” he says.
One possible example is metformin, one of the most commonly used medications for people with diabetes. “Metformin can be associated with low vitamin B12 levels,” Dr. Buse says. “People with profoundly low vitamin B12 levels can have significant cognitive impairment. For people on metformin, we measure B12 levels to make sure they’re normal or prescribe supplements to bring them back to normal.”
What You Can Do to Take Care of Yourself
Although the connection between diabetes and dementia is not understood, people with diabetes can take steps to reduce their risk. Namely, that means effectively managing diabetes, Dr. Buse says. That includes:
- Reducing weight if you are overweight or obese
- Controlling blood pressure and blood sugar
- Lowering cholesterol with statin medications
- Eating a broad diet that focuses on high-quality foods such as whole grains, nuts, fresh fruits and vegetables, and a wide assortment of fats
- Following a regular routine of moderate to vigorous exercise
- Taking aspirin if you have known vascular disease
- Not smoking
Need to talk to a doctor about your diabetes or dementia risk? Find one near you.