In a new study, researchers found that obesity is linked to a higher risk of dementia up to 15 years later.
They found that people who are obese in late adulthood face a 31% increased risk of dementia than those whose body mass index (BMI) is within the ‘normal’ range. The risk may be particularly high for women.
The findings suggest that weight management could play a big role in reducing risk.
The research was conducted by a team at UCL.
Current clinical guidelines suggest that obesity is an important modifiable risk factor linked to individual lifestyle behaviors.
But the association has remained somewhat unclear due to conflicting findings from different studies, with some suggestions that obesity could even be considered a protective health factor among older adults.
In the study, the research team collected data from 6,582 people in a nationally representative sample of the English population aged 50 years and over.
They found that people whose BMI was 30 or higher (at the obese level) at the start of the study period had a 31% greater risk of dementia, at an average follow-up of 11 years than those with BMIs from 18.5-24.9 (normal level).
There was also a big gender difference in the risk of dementia associated with obesity.
Women with abdominal obesity (based on waist circumference) had a 39% increased risk of dementia compared to those with a normal level.
This was independent of their age, education, marital status, smoking behavior, genetics (APOE ε4 gene), diabetes, and hypertension—and yet this association was not found among the male participants.
When BMI and waist circumference were viewed in combination, obese study participants of either gender showed a 28% greater risk of dementia compared to those in the normal range.
Prior evidence suggests that obesity might cause an increased risk of dementia via its direct influence on cytokines (cell signaling proteins) and hormones derived from fat cells, or indirectly through an adverse effect on vascular risk factors.
Some researchers have also suggested that excess body fat may increase dementia risk through metabolic and vascular pathways that contribute to the accumulation of amyloid proteins or lesions in the brain.
The team says it is possible that the association between obesity and dementia might be potentially mediated by other conditions, such as hypertension or anticholinergic treatments.
While not explored in this study, the research question of whether there an interactive effect between obesity and other midlife risk factors, such as high blood pressure, diabetes and APOE ε4 carrier status, in relation to dementia will be tested in upcoming work.
One author of the study is Dr. Dorina Cadar (UCL Institute of Epidemiology & Health Care).
The study is published in the International Journal of Epidemiology.
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