Topline
People who were overweight or obese when diagnosed with dementia had a lower risk of death than those at a normal weight, a new study found—raising further questions about how weight loss and nutritional health change as dementia progresses.
HEIDELBERG, GERMANY – MARCH 30: In this photo illustration a caregiver helps man to drink in nursing home on March 30, 2022 in Heidelberg, Germany. (Photo Illustration by Ute Grabowsky/Getty Images)
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Key Facts
Research published in the Journal of Alzheimer’s Disease found that patients with a body mass index of 30 to 34.9 at the time they were diagnosed had a 27% lower risk of death than patients with a normal BMI, while those with a BMI between 25 and 29.9% had a 16% lower risk.
People with class 2 and 3 obesity, meaning a BMI at or above 35, had a 22% lower risk of death, the study found.
The researchers used Health and Retirement Study data collected from 1998 through 2022, looking at 4,523 people who were dementia-free when they enrolled but were later diagnosed, and adjusted the analysis for factors like other chronic conditions, smoking and demographics.
The researchers looked for several forms of bias, including weight-loss confounding, collider bias (a statistical error from only studying people who developed dementia) and survivor bias, but they concluded these did not explain the association.
They still don’t know exactly why people who were overweight or obese had a lower risk of death, but said the findings support that weight at the time of diagnosis is a “meaningful prognostic signal.”
They believe being overweight or obese could help people with dementia because changes in the brain’s central drive can make it more difficult for patients to eat and feed themselves, and having extra weight, including more muscle mass and energy stores, could benefit patients.
KEY BACKGROUND
The study’s findings are particularly surprising because obesity is generally linked to worse health outcomes, and prior research has shown that obesity between the ages of 35 and 65 can increase the risk of getting dementia by around 30%. While prior research has largely looked at whether obesity contributes to chances of getting dementia in the first place, these new findings focus on what a person’s weight at the time of diagnosis says about their chances of survival.
SURPRISING FACT
Weight loss associated with dementia can begin a decade before the disease is diagnosed. A 2023 study found that weight loss accelerates in the years leading up to a diagnosis and continues afterward, but begins a decade or more before.
CRUCIAL QUOTE
“This doesn’t mean that patients with dementia should attempt to become overweight or obese, as our study was not designed to test that question,” said Virginia Chang, the study’s lead author.
FURTHER READING
Researchers Suggest Estrogen Replacement Therapy Could Fight Dementia. What To Know (Forbes)
6 Ways To Protect Your Brain Health Before It Becomes A Memory Problem (Forbes)
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