Body weight and risk for Dementia are both a confusing and complex topic. One can find reports that state obesity increases the risk for dementia as well as ones that indicate the opposite –that being underweight is the risk factor. And to make things even more confusing, there is evidence that indicates being overweight may protect some people from Dementia.*
It’s needless to say, these unexpected findings are difficult to explain and generate considerable discussion and controversy both in the media and between researchers.
However, what these seemingly conflicting findings show is risk – the factors that influence the likelihood of having Dementia is difficult to assess. A too high body mass index (BMI), uses an equation to calculate a numerical rating of your health based on height and weight, is only one of many known risk factors.
Therefore the big challenge is how to determine the combined effects of having multiple risk factors, such as diabetes, insufficient exercise, and smoking. Does having additional factors make having dementia three times more likely than being overweight alone? Or perhaps the risks compound and put people at 10 times the risk for Dementia?
Is it possible that having a high BMI becomes protective when combined with habits and activities known to reduce risk? As you can see, the number of environmental, behavioral, health-related and genetic influences is huge and the combinations of risk factors are infinite.
Another challenge is separating associative risks from those that cause the outcome. For example, obesity is associated with increased risk for diabetes, but in itself does not cause diabetes. What causes diabetes is the inability of the pancreas to produce sufficient insulin. And, as it turns out, having diabetes is a risk factor associated with having dementia later-in-life.
Therefore, based on what we currently know about BMI and risk for Dementia the best answer is, “it depends.” This means, at this time, the best we can to reduce risk is to make a lifelong commitment to what current clinical research shows are health-promoting habits.
*The Lancet Diabetes and Endocrinology, http://www.thelancet.com/journals/landia/article/PIIS2213-8587(15)00033-9/abstract), Accessed: September 2016.
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