Researchers found people who were obese at midlife were nearly 2.5 times more likely to develop dementia more than 20 years later than those who were normal weight.
But researchers say the link between obesity and dementia has not been thoroughly investigated. They say these results suggest that weight loss deserves further study as a possible means to reduce the risk of dementia and Alzheimer's disease.
Obesity Tied to Dementia Risk
In the study, Swedish researchers looked at the relationship between body mass index (BMI, a measurement of weight in relation to height used to indicate obesity) at midlife and the subsequent risk of dementia and Alzheimer's disease in nearly 1,500 people.
After an average of about 21 years of follow up, 61 participants were diagnosed with dementia and of those 48 had Alzheimer's disease.
The results showed that dementia and Alzheimer's disease was much more common among those who were obese at midlife. For example, people with a BMI over 30 (the definition of obese) at midlife were more than twice as likely to have dementia or Alzheimer's disease as those who were of normal weight.
Researchers say high blood pressure and total cholesterol levels at midlife also doubled the risk of dementia in later life, and the presence of more than one of these risk factors had an additive effect.
For example, when a person had all three of these risk factors at midlife, the risk of dementia or Alzheimer's disease was six times higher compared with someone with no risk factors.
The results appear in the October issue of the Archives of Neurology.