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How More Belly Fat Is Linked To Dementia: Liver Metabolizes Fat By Stealing Proteins From Brain

belly fat
Belly fat can make the liver work overtime, forcing it to tap into PPARalpha reserves in other parts of the body, including the brain. Tobyotter, CC BY 2.0

There are already so many reasons to lose the belly fat — the fatty area particularly responsible for obesity-related disease. But now, a new study sheds light on how too much abdominal fat can lead to dementia, as the liver steals proteins associated with memory and learning away from the hippocampus and other parts of the body, in order to help metabolize the fat. 

“We need to better understand how fat is connected to memory and learning so that we can develop effective approaches to protect memory and learning,” Dr. Kalipada Pahan, a professor of neurology at Rush University Medical Center, said in a statement.

Previous studies had already found that obese people were 3.6 times more likely to develop dementia than those of normal weight, but the link between the two incidents was unclear. Researchers at Rush University discovered that the protein, peroxisome proliferator-activated receptor alpha (PPARalpha), had responsibilities beyond helping the liver metabolize fat in the abdomen. It was also present in the hippocampus of the mice that were tested, and was involved with boosting learning and memory capability.

When abdominal fat was too much for the liver’s stores of PPARalpha to handle, the liver began tapping into PPARaplha reserves in other parts of the body, including the brain. Soon, these proteins became depleted, causing memory and learning impairment.

The researchers used two different kinds of genetically altered mice. They had PPARalpha deficiencies in either their hippocampus or in their livers. While PPARalpha deficiency in the brain was related to memory loss and an inability to learn, PPARalpha deficiency in the liver were unaffected. “Our study indicates that people may suffer from memory-related problems only when they lose PPARalpha in the hippocampus,” Dr. Pahan said in the statement, adding that more research needs to be conducted in order to determine the best way to maintain PPARalpha in the brain.

Low PPARalpha levels are just one of the many factors that contribute to obesity’s contribution to age-related memory loss. Earlier this year, British researchers presented a joint study that found that obesity affected performance on a number of memory and reasoning tests taken by participants over the course of 12 years. Another component of the study found that obese middle-aged individuals were twice as likely to develop dementia.

“We know dementia levels are going to rise because our population is growing older and Alzheimer’s disease is an illness of old age,” Tim Marsh, of the UK Health Forum, told the Guardian. “But it is clear that obesity is another factor that is putting more and more members of the population at risk. Recent research by several groups has indicated that individuals who are obese in their 40s and 50s have twice the average risk of getting dementia in their 70s.”

Source: Roy A, Jana M, Pahan K, et al. Regulation of Cyclic AMP Response Element Binding and Hippocampal Plasticity-Related Genes by Peroxisome Proliferator-Activated Receptor α. Cell Reports. 2013. 

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