Brain Health Study: Midlife Lipid and Glucose Levels Linked to Alzheimer's Disease
Did you know your health in middle age can have profound impacts on your risk of developing Alzheimer’s Disease? A recent study found that even at the young age of 35, cholesterol and blood glucose levels can impact your risk of developing Alzheimer’s Disease later in life. In this article, we break down the results of this study and how you can best support your health in midlife.
The study titled Midlife lipid and glucose levels are associated with Alzheimer's disease1 investigated how lipid (fat) and glucose (sugar) levels throughout adulthood may impact one’s risk of Alzheimer’s Disease.
Almost 5,000 people participated in the Framingham Heart Study, a 74-year ongoing cohort study that looks at factors contributing to heart disease. Each participant underwent examinations of cholesterol and blood glucose levels, blood pressure, and body mass index (BMI) every 4 years for a total of 37 years of follow-up. This unique study design allows researchers to see how certain markers of health throughout adult life may affect how people age and what diseases they develop. In this case, researchers observed which participants developed Alzheimer’s disease as they got older, and which lipid and glucose levels correlated with a higher or lower risk of Alzheimer’s disease at different phases of adulthood.
The results revealed that higher HDL cholesterol (“good” cholesterol) was associated with a reduced risk of Alzheimer’s Disease, while higher triglyceride, blood glucose, and diastolic blood pressure levels were associated with an increased risk of Alzheimer’s. What do all these terms mean? We’ll break them down further.
HDL cholesterol (high-density lipoprotein) is often considered the “good” cholesterol as it absorbs other types of cholesterol and brings it to the liver, which then flushes it from the body. An ideal HDL level for adults is greater than 60 mg/dL. Having a 15 mg/dL elevation in HDL as early as the age of 35 corresponded to a 15% reduced risk of Alzheimer’s disease. In middle adulthood between the ages of 51-60, HDL levels provided an 18% reduced risk of developing Alzheimer’s later in life. HDL levels in late adulthood (age 61-70) were not associated with the risk of Alzheimer’s.
Triglycerides are the most common type of fat in your body, and come from foods, especially butter, oils and other fats you eat. These lipids (waxy fats) are stored in your body as fat cells. Thus, it is ideal to keep triglycerides low. A healthy triglyceride level is less than 150 mg/dL. In early adulthood (age 35-50), high triglycerides were associated with a 30% increased risk of Alzheimer’s in the study. However, in middle and late adulthood, there was no association between triglyceride levels and Alzheimer’s risk.
Blood glucose (aka blood sugar) levels can have many effects on health so it’s important for these levels to remain within a healthy range. Healthy blood glucose levels are less than 100 mg/dL after fasting for 8 hours, or less than 140 mg/dL 2 hours after eating. In middle adulthood, every 15 mg/dL increase in blood sugar corresponded to a 14.5% increased risk of Alzheimer’s. There was no association between blood glucose levels in early and late adulthood and Alzheimer’s risk.
Diastolic blood pressure is the second number recorded in blood pressure and represents the pressure in between heartbeats. High diastolic blood pressure is linked to a higher risk of heart disease, aneurysm, and peripheral artery disease. A typical diastolic blood pressure value is 80 mmHg. In the Framingham Heart Study, elevated diastolic blood pressure was associated with an increased risk of Alzheimer’s only in late adulthood.
In the study, Alzheimer’s risk was not associated with LDL cholesterol (aka bad cholesterol), BMI, smoking, or systolic blood pressure at any age.
Takeaways for Brain Health
Optimizing your lipid and glucose levels throughout your life can help support your brain and reduce your risk of Alzheimer’s Disease. The good news is that there are several lifestyle and dietary factors that help you boost HDL cholesterol, lower triglycerides, and lower blood glucose. And all of these factors also directly support brain health!
Keeping your lipid and glucose levels in check throughout adulthood also reduces your risk for cardiovascular disease and diabetes. These chronic diseases can significantly impact quality of life and further increase your risk of Alzheimer’s disease.
Here are some key lifestyle and dietary factors to support vascular, metabolic, and brain health:
- Exercise: physical activity can boost HDL levels and decreases triglycerides by using up some of the fat stored in the body for energy. Aerobic exercises like walking, running, swimming, or cycling also help lower blood glucose.
- Eat healthy fats: foods like nuts, seeds, avocado, olive oil, and fatty fish like salmon provide healthy omega-3s to reduce triglycerides, boost HDL cholesterol, and help regulate blood glucose. It may seem counterintuitive to eat more fats to improve cholesterol levels, but healthy fats are a very important part of a brain-healthy diet. Look for mono- and polyunsaturated fats, and limit saturated and trans fats that come from foods like margarine, fried foods, and commercial baked goods.
- Consume more fiber: Fiber is a type of carbohydrate that our digestive tract cannot break down and absorb, so fiber-rich foods help prevent spikes in blood glucose. They also reduce the absorption of cholesterol from foods to improve lipid levels. Foods like oats, quinoa, barley, beans, peas, and seeds are high in fiber.
- Eat a diversity of fruits and vegetables: Non starchy vegetables like leafy greens, zucchini, green beans, and Bok Choy provide fiber and antioxidants to help support healthy cholesterol and glucose levels. Fruits that are lower in sugar like berries and citrus are also great sources of fiber and antioxidants.
- Manage stress: chronic stress can also increase cholesterol and blood glucose. Practicing ways to reduce stress like meditation, yoga, spending time with family and friends, getting enough sleep, or writing in a journal can help keep lipid and glucose levels in a healthy range.
The results of this research study allow us to take small steps toward optimizing our lipid and glucose levels to best support lifelong brain health.
- Zhang, X., Tong, T., Chang, A., et al., Midlife lipid and glucose levels are associated with Alzheimer’s disease. Alzheimer’s Dement., 2022, 1–13.