25) to an increased risk of cognitive decline. Preventing or controlling those chronic conditions now may not only protect you from serious problems like Alzheimer’s down the road, but it may even help you think more clearly today.You may be surprised to find that underlying health problems can make it harder to remember someone’s name or puzzle through a complex problem. But research has consistently linked high blood pressure, diabetes, and obesity (25) to an increased risk of cognitive decline. Preventing or controlling those chronic conditions now may not only protect you from serious problems like Alzheimer’s down the road, but it may even help you think more clearly today.
You know that having high blood pressure puts you at risk for heart disease, but increasing evidence shows it can also affect your brain health. Two large, recent studies show a significant link between high blood pressure and the risk of dementia, including Alzheimer’s disease. High blood pressure, or hypertension, can damage tiny blood vessels in the brain and lead to scarring (called lesions) in the brain’s white matter, its communication system. That breakdown in brain cell communication leads to cognitive decline and dementia. In both studies, systolic blood pressure (the top number) was the critical factor, and since the damage was cumulative, the researchers emphasized that getting and keeping blood pressure under control in early and midlife is essential to protect your brain as you get older.
The first study, published in 2009 in the Journal of Clinical Hypertension, looked at brain scans of more than 1,400 postmenopausal women and found that those who had blood pressure above 140/90 mm Hg (hypertension)—whether or not they were taking blood pressure medication—had more and larger white matter lesions than those whose blood pressure was under control. The second study, published in 2010 in the journal Stroke, found that white matter damage increased with every twenty-point jump in systolic blood pressure.
Getting your blood pressure down to 120/80 mm Hg or below not only appears to protect you against dementia, but it also significantly lowers your risk of stroke and other blood vessel damage. The National Institutes of Health is currently investigating whether aggressively treating hypertension to lower systolic blood pressure to below 120 (“normal”) offers additional health benefits. This Systolic Blood Pressure Intervention Trial (SPRINT) study is the first clinical trial of its kind and is expected to have results by 2018. Until then, talk to your doctor about how lifestyle changes and supplements can keep your blood pressure under control (52), or whether or not you should take medication.
Experts are still trying to figure out exactly how diabetes influences brain health, but research shows that diabetics are one-and-a-half times more likely to experience mild cognitive impairment, vascular dementia, and Alzheimer’s disease than people without diabetes. High blood sugar, excess insulin, and problems with insulin sensitivity all appear to be factors (25), affecting brain cells, memory function, and your ability to learn. For example, a 2009 study in the journal Diabetes Care found that even a 1 percent increase in A1C levels (a long-term measure of blood sugar) was linked to lower scores on cognitive tests. Other research reveals that people with and without diabetes who have poor blood sugar control—either too high or too low—have worse cognitive performance.
Insulin is also critical for good brain health: It helps transport glucose to brain cells for energy and plays a role in many brain functions, including cognitive processes. When your brain doesn’t have enough insulin, or if the insulin isn’t working properly (called insulin resistance), it can result in cognitive decline. Insulin resistance, for example, seems to be a factor in Alzheimer’s, since people with the disease can’t regulate their blood sugar as efficiently. And studies show that too much insulin can age your brain and increase risk of cognitive decline and dementia, including Alzheimer’s disease.
To protect your brain, as well as the rest of your body, aim to keep your blood sugar under 100 mg/dL, the cutoff point for prediabetes. Exercising regularly and eating fewer processed and refined foods will go a long way toward preventing or controlling diabetes (13, 25, 50, 55). And if you already have diabetes, your best bet for brain health is to work with your doctor to keep tight control over your blood sugar levels.