People with a higher body-mass index are more likely to develop dementia, new research finds.
Being classed as overweight rather than in the normal range increases the dementia risk by 16-33%.
For a person who is 170cm (5’7″), for example, carrying an extra 14.5kg (32lbs) over the ideal weight, will increase their dementia risk between 16 and 33%.
Being classed as obese (an additional 14.5kg) adds the same amount of dementia risk again, making a total of up to 66%.
The study analysed data from 1.3 million adults in the US and Europe.
Professor Mika Kivimäki, the study’s first author, said:
“The BMI-dementia association observed in longitudinal population studies, such as ours, is actually attributable to two processes.
One is an adverse effect of excess body fat on dementia risk.
The other is weight loss due to pre-clinical dementia.
For this reason, people who develop dementia may have a higher-than-average body mass index some 20 years before dementia onset, but close to overt dementia have a lower BMI than those who remain healthy.
The new study confirms both the adverse effect of obesity as well as weight loss caused by metabolic changes during the pre-dementia stage.”
Previous studies have given conflicting messages about the effect of obesity on dementia.
Some have suggested more weight may have a protective effect, others, like this one, the reverse.
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The study was published in the journal Alzheimer’s & Dementia (Kivimäki et al., 2017).