Brain Health

Are Obesity And Alzheimer's Related?

Are Obesity And Alzheimer's Related? about undefined
Obesity is a well-known risk factor for Alzheimer's disease. But new research shows there may be more to the link between having a higher percentage of body fat and developing dementia. Researchers at the University of Texas Health Science Center at San Antonio are pointing to genes. Here's the story and how you can use these new findings to better protect your memory...

Alzheimer's disease and the growing link to obesity

Over 55 million people worldwide have dementia, according to the World Health Organization (WHO). Alzheimer’s disease is the most common type of dementia affecting 32 million people. Previous research suggests that maintaining an appropriate body mass index (BMI) for your height may reduce your risk for Alzheimer’s disease. A person is obese if their weight is higher than what is believed to be normal for their height. You can calculate your BMI by taking your weight in pounds divided by your height squared in inches and multiplying it by 703. A BMI over 25 suggests you're overweight, while a BMI of 30 to 39 suggests you're obese and a BMI of 40 or more indicates morbid obesity. In addition, a recent study found that neurodegeneration caused by obesity is similar to that of Alzheimer’s disease... which suggests that controlling weight could help slow cognitive decline and lower your risk for Alzheimer’s. Other research shows that obesity triggers inflammation in the body. This leads to an increased risk for developing dementia, and other diseases including cardiovascular disease, stroke, and diabetes. The research is another reason why doctors encourage you to lose weight if you have a high body mass index or suffer from abdominal obesity. But there's more...

The case for a genetic link

In a study published in February 2023, researchers from The University of Texas Health Science Center at San Antonio discovered that 21 out of 74 known genes related to Alzheimer’s are also linked to obesity. Scientists are hopeful that this may help explain why adults who experience obesity during midlife frequently develop Alzheimer’s disease. The research team decided to look for a genetic link between obesity and Alzheimer’s because they knew from previous studies that obesity, especially in midlife, was a known risk factor – even though they don’t completely understand why. Dr. Claudia Satizabal is assistant professor at the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases and the University of Texas Health Science Center-San Antonio. She’s also the study’s corresponding author. Dr. Satizabal explained, saying, “We asked the question, what if obesity changes the expression of key genes implicated in Alzheimer’s that could help explain some of the mechanisms linking these two conditions?”

Genetic link: Alzheimer's and obesity llinked genes mean higher risk

In the study, Dr. Satizabal and her team analyzed 74 Alzheimer’s-related genes from more than 5,600 participants of the famed Framingham Heart Study. From this analysis, researchers discovered that of those 74 genes, 21 were either under-expressed or over-expressed in obesity. What’s more, scientists also found 13 Alzheimer’s- related genes linked to BMI, and eight linked to waist-to-hip ratio. While they expected some associations because of the recent genetic studies of Alzheimer’s that point to genes involved in lipid metabolism and the immune system – both of which become dysregulated in obesity, the results were still a surprise. “However, we were a little surprised to see as many – the expression of nearly 30 percent of the Alzheimer’s disease genes showed links with obesity,” Dr. Satizabal added.

What should you do?

Dr. Satizabal stressed that she and her team can’t derive immediate recommendations for patients from this study. However, in our opinion the medical world should sit up and listen because growing health research directly links excess body fat and dementia risk. She added, “It’s important to discuss with patients the implications of excess weight, especially obesity, to preserve cardiovascular and brain health as we age.” The limitation of the study is that the data from the Framingham Study was from a mostly white population. Dr. Satizabal believes other ethnicities may have an even stronger link. Dr. Satizabal says, “We think the associations between Alzheimer’s-related genes and obesity might be even more relevant in Hispanics, who have a higher prevalence of obesity. But that is yet to be tested. We need to increase the sampling of diverse populations to find more genetic markers related to dementia.” Their next step is to sample dementia-related genetic markers in more diverse populations, and to follow up on key cellular and molecular mechanisms. Meanwhile, other experts are weighing in on what we should do with this new research.

If you are at increased risk for Alzheimer's disease...

Dr. Santosh Kesari, neurologist at Providence St. John’s Health Center in Santa Monica, and regional medical director for the Research Clinical Institute of Providence Southern California, said he wasn’t surprised by the study’s findings because they know obesity triggers many health problems. However, Dr. Kesari stresses that we by no means know the full story yet. He added, “It seems some of the story is in this new publication because some of the genes involved that are related to obesity and the increased risk of Alzheimer’s in this dataset highlight the role of neuroinflammation.” “At least a few of the genes are linked. We know obesity causes inflammation and some of those same genes seem to be implicated in neuroinflammation, which we think is one of the underlying mechanisms of dementia, including Alzheimer’s.” Dr. Kesari stressed that the earlier you can start preventive measures, the better. If you have genetic risk for Alzheimer’s and know it in your 30s or 40s, start early to adjust your lifestyle and lower your weight to reduce your risk factors for dementia decades later.

What about people who already have dementia?

Once you already have Alzheimer’s, weight reduction is still important, but it won’t have nearly the impact on your brain that it does earlier in life. However, we believe that it's never too late to choose a healthier lifestyle. By reducing weight then you can reduce your blood pressure, your blood sugar and reduce your risk of major health challenges (such as heart disease)as well as reduce insulin resistance or any vascular risk factors (like poor blood flow) that could be contributing to your memory loss. Best of all, when you maintain a healthy weight, you'll feel better and be able to live a more active lifestyle. It’s not only healthier for your body and your brain, it's a lot more fun. Best Regards, The Awakening From Alzheimer’s Team
https://www.who.int/news-room/fact-sheets/detail/dementia https://jamanetwork.com/journals/jamaneurology/article-abstract/2792227 https://www.nature.com/articles/s41588-022-01024-z https://www.nhlbi.nih.gov/science/framingham-heart-study-fhs  

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