Obesity in people aged above 50 puts them at 28% more risk of developing dementia, finds study
The secret to keeping the brain healthy and sharp may lie around the belly. Larger waist size may place older adults, especially women, at a higher risk of developing dementia a decade-and-a-half later, a new study found. However, people can make some lifestyle modifications to cut that risk.
Researchers from the UK followed more than 6,000 participants for 15 years, keeping tabs on their height, weight, waist circumference and brain function. They found that women with more belly fat — with waist circumference measuring more than 88 cm — had a 39% greater risk of dementia than their counterparts with lower waist size. For obese men and women over 50 years of age, the risk stood at 28%.
According to the Centers for Disease Control and Prevention (CDC), dementia is not a disease but a general term that describes an impaired ability to remember, think or make decisions. Over 5.8M Americans are living with dementia, of which Alzheimer's disease is the most common form. "Our findings suggest that rising obesity rates will compound the issue," Andrew Steptoe, a study co-author and professor of psychology and epidemiology at University College London, told CNN.
The research included 6,582 UK adults aged over 50. During the 15-year study period, researchers interviewed these participants to gauge their physical and mental fitness. Between 2002-2017, 453 or 6.9% of the participants developed dementia. They then looked for links between waist size and obesity risk after removing other factors that may also put people at risk of dementia such as sex, baseline age, education, physical activity, smoking and a gene linked with Alzheimer's disease: apolipoprotein E-ε4.
Their results showed that 74% of the participants who developed dementia were overweight or obese and the risk was higher for women with belly fat. "Our results suggest that having an increased body weight or abdominal obesity are associated with increased dementia incidence. These findings have significant implications for dementia prevention and overall public health," the researchers said.
Commenting on these findings, Dr Richard Isaacson told CNN that people who want to protect their brain health over time should pay attention to their waist size. He heads the Alzheimer's Prevention Clinic at Weill Cornell Medicine and New York-Presbyterian Hospital. Studies have linked waist-to-hip ratio (WHR) with cognitive decline. Some scientists have noted that a part of the brain involved in memory shrinks in people with obesity. Still, the researchers do not have a clear understanding of how body fat drives dementia.
But there are theories. One study suggested that fat around the belly makes hormones that could harm the brain. Another possible explanation is that body fat may play a part in triggering a buildup of harmful brain proteins that are tied to dementia. UK researchers believe that targetting obesity could bring down the dementia burden. It can be done by identifying individuals at a higher risk of cognitive decline. In the future, they hope to include more people in the study to better understand the underlying mechanisms. Until then, the researchers recommend eating healthy and exercising to stave off obesity.
The study is published in the International Journal of Epidemiology.