People who are overweight or obese in midlife have 80% higher risk of developing dementia, Alzheimer's disease or vascular dementia in old age, says a new study.
"Currently, 1.6 billion adults are overweight or obese worldwide and over 50 pc of adults in the US and Europe fit into this category," said study author, Weili Xu at Karolinska Institute in Stockholm, Sweden.
"Our results contribute to the growing evidence that controlling body weight or losing weight in middle age could reduce your risk of dementia," he added.
Researchers studied information from the Swedish Twin Registry on 8,534 twins aged 65 or above. Of these, 350 were diagnosed with dementia and 114 had possible dementia. The body mass index (BMI) of these subjects had been taken 30 years earlier.
According to the study, 2,541 twins or nearly 30 pc were found to be either overweight or obese during middle age. Being overweight was defined as having a (BMI) between 25-30 and obesity was defined as a (BMI) of higher than 30.
The results remained the same after considering other factors such as education, diabetes and vascular disease.
The study shows that a total of 26 pc of those with no dementia had been overweight in midlife compared to 36 pc of those with questionable dementia and 39 pc of those with diagnosed dementia.
Three pc of those with no dementia had been obese in midlife, compared to five pc of those with questionable dementia and seven pc of those with diagnosed dementia.
Researchers also analyzed twin pairs where one twin had dementia and other did not, and found that there was no longer a significant relationship between overweight and obesity and dementia in midlife.
"This suggests that early life environmental factors and genetic factors may contribute to the link between midlife overweight and dementia," Xu said.
The research is published in the current print issue of Neurology(r), the medical journal of the American Academy of Neurology.