Being Too Thin in Middle Age May Boost Dementia Risk
There’s an old saying that you can never be too rich or too thin. Most of us will never have occasion to test the truth of the former, but the latter is evidently incorrect. You can be too thin for your own good. At least, that’s the apparent message behind new research from British researchers, who looked at body mass index (BMI) and subsequent risk of being diagnosed with dementia.
According to investigators at the London School of Hygiene & Tropical Medicine, people who are underweight in middle age are 34% more likely to develop dementia than people who maintain normal body weight. Obese people were actually about 30% less likely to be diagnosed with dementia. Even after adjusting for possible confounding factors, such as alcohol use, or smoking, the findings held up.
Scientists aren’t sure why being dagger thin should be associated with an increased risk of dementia later in life. Nor do they understand why being overweight should appear to confer a certain amount of protection against the loss of memory and reasoning ability that come with dementia.
"The reasons why a high BMI might be associated with a reduced risk of dementia aren't clear, and further work is needed to understand why this might be the case," said Dr. Nawab Qizilbash, the study's lead author. "If increased weight in mid-life is protective against dementia, the reasons for this inverse association are unclear at present. Many different issues related to diet, exercise, frailty, genetic factors, and weight change could play a part."
Other investigators counter that this may not be the final word, however. Professor Deborah Gustafson from SUNY Downstate Medical Center, New York, wrote, "The published literature about BMI and dementia is equivocal. Some studies report a positive association between high mid-life BMI and dementia, whereas others do not…”
So, while the jury is still out on the subject, there’s some evidence that it may not be desirable to be “too thin” after all. And that dovetails nicely with my philosophy, which is to be “real, not ideal.”
Nawab Qizilbash, John Gregson, Michelle E Johnson, Neil Pearce, Ian Douglas, Kevin Wing, Stephen J W Evans, Stuart J Pocock. BMI and risk of dementia in two million people over two decades: a retrospective cohort study. Lancet Diabetes Endocrinol, April 2015 DOI: 10.1016/S2213-8587(15)00033-9