Dementia: Lifetime weight gain or loss predicts risk


Dementia is a growing global public health problem, currently affecting 50 million people and projected to rise dramatically to more than 150 million cases worldwide by 2050. Obesity, commonly measured by the body mass index (BMI, which is obtained by dividing weight by the square of height), continues to be a global epidemic and previous studies have suggested that being in middle age can lead to an increased risk of dementia. But the association between BMI and dementia risk has always remained difficult to explain. Now, researchers from Boston University’s Chobanian & Avedisian School of Medicine and the Chinese Academy of Medical Sciences & Peking Union Medical College have found that different patterns of change in BMI over the course of a lifetime may be an indicator of the risk of a person’s dementia.


“These findings are important because previous studies looking at weight trajectories have not considered how patterns of weight gain/stability/loss might help signal that dementia is potentially imminent,” explained corresponding author Rhoda Au. , professor of anatomy and neurobiology. Through the Framingham Heart Study , one group of participants was followed for 39 years and their weight measured approximately every 2 to 4 years. The researchers compared the different patterns of weight (stable, gain, loss) between those who did and those who did not develop dementia

They found that the general trend of decreasing BMI was associated with a higher risk of developing dementia. However, upon further exploration, they found a subset with a pattern of initial BMI increase followed by decline , both occurring during midlife, that appeared to play a central role in the declining BMI–dementia association .

Au points out that it is relatively easy for individuals, family members and general practitioners to monitor weight. “If after a steady weight gain (common with advancing age), you experience an unexpected change towards weight loss after midlife, it would be good to consult your GP and find out the reason. Some potential treatments are emerging for which early diagnosis could be critical to efficacy of one of these treatments, once approved and made available,” adds the researcher. The researchers hope this study illustrates that the seeds of dementia risk are sown over many years, possibly even throughout the life span. “Dementia is not necessarily inevitable and monitoring risk indicators, something easy to notice, such as weight trends, could offer opportunities for early intervention that can change the trajectory of disease onset and progression.”

The study was published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.

  • BMI decline patterns and relation to dementia risk across four decades of follow-up in the Framingham Study (


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