HealthDay News — A new study of nearly two million people suggests that those who are overweight or obese in middle age may be less likely to develop dementia than their normal-weight and underweight peers. The report was published online in The Lancet Diabetes & Endocrinology.
Nawab Qizilbash, MD, from OXON Epidemiology Ltd. in Madrid, and colleagues analyzed nearly 20 years of medical records on 1,958,191 British adults, whose average age was 55 at the start of the study. During 15 years of follow-up, 45,507 of the participants developed dementia.
Overweight and obese people were about 30% less likely to develop dementia 15 years later than people of a healthy weight. Conversely, underweight people were 34% more likely to develop dementia than those whose weight was normal, according to the study authors.
The associations between weight and dementia held up even after the researchers took into account when the participants were born or their age at diagnosis. And factors such as drinking and smoking, which are known risk factors for dementia, made little difference in the results, the researchers added.
Deborah Gustafson, PhD, a professor of neurology at the SUNY Downstate Medical Center in New York City, and author of an accompanying editorial in the journal, questioned the study’s methods. Specifically, she wondered whether weight measured in middle age actually reflects the risk of dementia 15 years later. Since there are genetic components to both weight and dementia, the role of weight by itself isn’t clear, she told HealthDay.
“Despite the high number of participants [in the study], it is not the final word, given the methodological questions,” Gustafson said. “More research is needed, as well as clarification of these results.”
Qizilbash N, et al. BMI and risk of dementia in two million people over two decades: a retrospective cohort study. Lancet Diabetes Endocrinol. 2015; doi: 10.1016/S2213-8587(15)00033-9.
Gustafson D. BMI and dementia: feast or famine for the brain? Editorial. Lancet Diabetes Endocrinol. 2015; doi: 10.1016/S2213-8587(15)00085-6.