LONDON — A surprising study contradicting all previous research found that being fat in middle age appears to cut the risk of developing dementia rather than increase it, the Lancet scientific journal has reported.
A study of two million people found that the underweight were far more likely to develop dementia, a growing problem among the elderly in the Western world.
Underweight people had a 34 percent higher risk of developing dementia than those of a normal weight, the study found, while the very obese had a 29 percent lower risk of becoming forgetful and confused and showing other signs of senility.
Obesity levels, like dementia levels, are soaring worldwide.
Researchers said that if other studies confirm the findings, the next step would be to examine if people who eat more unknowingly take in dementia-fighting nutrients in the extra food they consume.
The study, published in the Lancet Diabetes and Endocrinology Journal, flies in the face of previous smaller studies — and much modern health advice — that what is good for the heart is also good for the head.
A 2008 study of 6,000 people published in the Neurology journal found that people who have big bellies in their ’40s were much more likely to get Alzheimer’s and other forms of dementia in their ’70s. That study was among the first to link middle-aged spread to a fading mind.
But the new research “overshadows those (previous studies) by orders of magnitude,” said Nawab Qizilbash of Oxon Epidemiology, who led the study. “We show completely the opposite,” Qizilbash said, as quoted by the Times of London.
Patients were an average 55 years old and 45,507 of them developed dementia over an average of nine years. The risk of dementia fell steadily as their weight rose, the researchers found.
Qizilbash, as quoted in the Times, said the findings held despite attempts to adjust it for other causes of dementia and the tendency of obese people to die earlier.
“We did a lot of analysis to see if we could explain it but it just seems to persist. We couldn’t get rid of it, so we’re left with this apparent protective effect,” the scientest was quoted as saying.
The co-author of the paper said the results suggested “that doctors, public health scientists and policymakers need to re-think how to best identify who is at high risk of dementia.”
“If we can understand why people with a high body mass index have a reduced risk of dementia, it’s possible that further down the line, researchers might be able to use these insights to develop new treatments,” Stuart Pocock of the London School of Hygiene and Tropical Medicine was quoted as saying by the London newspaper.
Qizilbash warned, however, that being overweight or obese brings with it a much higher risk of death from any cause and a higher risk of stroke and other diseases.
“So even if there is a protective effect against dementia from being overweight or obese, you’re not living long enough to benefit from it,” Qizilbash was quoted as saying by the Times.