Obesity Can Increase Your Risk
of Dementia By Up To 80 Percent
Being obese can increase the risk of Alzheimer’s
Disease by as much as 80 per cent, according to a study in the
May issue of Obesity Reviews.
But it’s not just weight gain that poses a risk. People who are
underweight also have an elevated risk of dementia,
unlike people who are normal weight or overweight.
US researchers carried out a detailed review of 10 international
studies published since 1995, covering just over 37,000 people,
including 2,534 with various forms of dementia. Subjects were
aged between 40 and 80 years when the studies started, with follow-up
periods ranging from three to 36 years.
The review, which included studies from the USA, France, Finland,
Sweden and Japan, also included a sophisticated meta-analysis
of seven of the studies, published between 2003 and 2007 with
a follow-up period of at least five years.
All kinds of dementia were included, with specific reference
to Alzheimer’s Disease and to vascular dementia – where areas
of the brain stop functioning because the blood vessels that supply
them are damaged by conditions such as high blood pressure or
heart disease.
“Our meta-analysis showed that obesity increased the relative
risk of dementia, for both sexes, by an average of 42 per cent
when compared with normal weight” says Dr Youfa Wang, Associate
Professor of International Health and Epidemiology at Johns Hopkins
Bloomberg School of Public Health, Baltimore.
“And being underweight increased the risk by 36 per cent.
“But when we looked specifically at Alzheimer’s Disease, the
increased risk posed by obesity was 80 per cent. The increased
risk for people with vascular dementia was 73 per cent.
“The risks were greater in studies where sufferers developed
Alzheimer’s Disease or vascular dementia before the age of 60
or in studies with follow-up periods of more than 10 years.
“We also found that obesity was more likely to be a risk factor
for women when it came to developing Alzheimer’s Disease and for
men when it came to vascular dementia.”
The authors estimate that 12 per cent of the dementia risk in
the study population could be attributed to obesity, with this
rising to just over 21 per cent in patients with Alzheimer’s Disease.
It’s estimated that up to 10 per cent of people aged 65 or more
suffer from some form of dementia and two-thirds of those have
Alzheimer’s Disease.
“There has been controversy about the links between obesity and
dementia for a number of years, but previous findings have been
mixed and inconclusive” says Dr Wang.
“The advantage of carrying out a meta-analysis is that it provides
researchers with access to a large number of study subjects and
it is possible to iron out the inconsistencies and come to overarching
conclusions.
“Our detailed analysis clearly shows a U-shaped relationship
between weight and dementia, with people who are obese or underweight
facing a greater risk.
“We believe that our results show that reducing the prevalence
of obesity is a promising strategy for preventing the progression
of normal ageing into Alzheimer’s Disease.”
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