When it comes to Alzheimer's prevention, most women focus on doing brain games and eating generous doses of omega-3 fatty acids ( avocado, anyone?). But mounting evidence shows that they also need to pay more attention to their blood sugar levels.
According to new research published in Diabetologia, if left untreated, insulin resistance, which results in excessively high blood sugar levels, may be one of the first signs of cognitive decline and Alzheimer's to come -- especially in women. Alzheimer's is an irreversible brain disorder that reduces cognitive skills over time, eventually leading to the inability to perform routine tasks. More than five million Americans currently have the disease. Almost two-thirds of them are women, according to the Alzheimer's Association.
For the study, researchers from the University of Turku in Finland tested the language skills, semantic memory and executive functions of 5,935 men and women, ages 30 to 97. The brain's temporal lobe, which tends to be smaller in people with higher levels of insulin resistance, is primarily responsible for these functions. The researchers found that higher levels of insulin resistance were associated with poorer scores in women, but not in men.
This research suggests that women's brains may be more vulnerable to the effects of insulin resistance than men's brains, says lead study author Laura Ekblad, a researcher at the University of Turku in Finland. She notes that previous research shows that lesions in the brain, called white matter hyperintensities, are common in people with metabolic problems such as insulin resistance, but are more common in women than they are in men.
"More and more evidence from studies on cellular mechanism show that insulin has specific and important effects on the brain. When insulin resistance is present, there is too much insulin circulating in the blood flow, which leads to a reduced transportation of insulin to the brain," Ekblad says. "Previous studies show that reduced brain insulin levels can directly contribute to cognitive decline and the pathophysiology of Alzheimer's disease in multiple ways."
For instance, apart from contributing to brain lesions, insulin resistance alters the flow of blood and the delivery of glucose (or sugar) to brain cells to use as fuel, says Abbott medical director Refaat Hegazi. Also, as Type 2 diabetes is a risk factor for cardiovascular disease, elevated blood cholesterol, mainly LDL cholesterol, values can lead to vascular changes in the brain. Research from Albany University in 2013 has even suggested that Alzheimer's disease is actually just the late stages of Type 2 diabetes.
Know Your Blood Sugar Levels, Reduce Your Alzheimer's Risk
The most alarming -- and potentially lifesaving -- aspect of this study is that, by including young and middle-aged adults, it found that the link between insulin resistance and poorer cognition is present years before both the onset of severe cognitive problems and, in many cases, before the diagnosis of Type 2 diabetes.
After all, more than 1 out of 3 adults have prediabetes, a condition in which the body's blood sugar levels are too high -- but not high enough to be classified as diabetic. During prediabetes, the body becomes increasingly resistant to insulin. However, 9 of out 10 people with prediabetes don't know they have it. Meanwhile, approximately 29.1 million Americans -- or 9.3 percent of the population -- have diabetes, according to the Centers for Disease Control and Prevention. About 30 percent of them are undiagnosed.
That's why it's so important, especially if you are overweight, have high blood pressure or abnormal cholesterol levels, to get your blood sugar levels checked with a routine blood test. Your primary care provider can perform one during your next annual physical, or if you are especially concerned about your levels, you can stop in sooner.
If you learn that you do have diabetes, a 2015 study in the World Journal of Diabetes shows that properly managing the disease through prescription medications may reduce or delay the onset of Alzheimer's disease. "People with uncontrolled Type 2 diabetes open themselves up to health issues from insulin resistance, particularly its negative effects on the brain's blood vessels and nerves, Hegazi says.
However, unlike diabetes, prediabetes is not only treatable, but reversible. Lifestyle changes, such as diet and exercise, may decrease the percentage of prediabetic patients who develop diabetes to 20 percent, according to a 2014 review published in The Permamente Journal. And by reducing your risk of diabetes, you can reduce your risk of Alzheimer's disease.
Whatever your current blood sugar level, Ekblad says, taking control of it now may mean the difference between a future with or without Alzheimer's.