A large study from South Korea has found that middle-aged adults with metabolic syndrome—an unhealthy cluster of conditions including belly fat and high blood pressure—may face a higher risk of developing dementia before age 65. The study was published in the journal Neurology and involved nearly two million people.
Young-onset dementia is diagnosed when symptoms appear before the age of 65. While it’s less common than dementia in older adults, it can have a major impact, affecting people during their working years or while they’re still raising families. This study does not prove that metabolic syndrome causes dementia, but it does show a strong connection.
Metabolic syndrome is a medical term used when a person has belly fat plus at least two other risk factors: high blood pressure, high blood sugar, high levels of triglycerides (a type of fat in the blood), or low levels of HDL cholesterol—the “good” cholesterol. All of these conditions increase the risk of heart disease and diabetes, but this study shows they may also be linked to brain health.
The researchers, led by Dr. Minwoo Lee of Hallym University Sacred Heart Hospital, used data from South Korea’s national health insurance system to track the health of adults aged 40 to 60 who had regular checkups between 2009 and 2015.
These checkups included measurements of waist size, blood pressure, blood sugar, and cholesterol. About 25% of the participants were found to have metabolic syndrome.
Over the following eight years, nearly 9,000 people developed some form of dementia—about 0.45% of all participants. But among those with metabolic syndrome, the rate was almost twice as high: 0.86 cases per 1,000 person-years, compared to 0.49 for those without it.
“Person-years” means the total number of people in the study, multiplied by how long they were followed.
Even after adjusting for other health and lifestyle factors—like age, physical activity, education level, depression, and stroke—people with metabolic syndrome had a 24% higher risk of dementia.
When looking at specific types, the syndrome was linked to a 12% higher risk of Alzheimer’s disease and a 21% higher risk of vascular dementia, which is caused by reduced blood flow to the brain.
The risk was even higher in women. Female participants with metabolic syndrome had a 34% increased risk of developing dementia, while the risk for men was 15% higher. Younger participants in their 40s were also more at risk than those in their 50s.
Perhaps most concerning, the risk of dementia increased as more risk factors were present. Participants with all five components of metabolic syndrome had a 70% greater risk of developing dementia than those with none.
These findings suggest that taking care of your health in midlife—especially by reducing belly fat, controlling blood pressure and sugar, eating well, exercising, and quitting smoking—may help lower the risk of developing dementia at a younger age.
Dr. Lee emphasized the importance of lifestyle changes. “Our findings suggest that reducing the risk of metabolic syndrome may help reduce the risk of young-onset dementia,” he said. However, he also noted that more long-term research is needed.
Future studies should track people over a longer time and use brain scans to look for early signs of dementia. This could help confirm whether there’s a direct link and better explain how metabolic syndrome affects brain health.
One limitation of the study is that it didn’t take into account genetic risks for Alzheimer’s, such as carrying the APOE4 gene, which is known to increase dementia risk. Still, the findings offer a powerful reminder: protecting your heart and metabolic health might also help protect your brain.
If you care about dementia, please read studies about dietary strategies to ward off dementia, and how omega-3 fatty acids fuel your mind.
For more health information, please see recent studies about Choline deficiency linked to Alzheimer’s disease, and what to eat (and avoid) for dementia prevention.
The research findings can be found in Neurology.
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