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Obesity may even affect the brain and memory, leading to its decline, according to a new study by researchers from the University of Alabama at Birmingham. The study found that some "epigenetic changes that dysregulate memory-associated genes are associated with chronic obesity". Hence, it found an enzyme in brain neurons of the hippocampus, a brain structure that is said to be related to memory.

Earlier studies found impairment of memory in obese, middle-aged or older people. But its underlying molecular mechanisms were not familiar. However, long-term memory creation is caused by changes in DNA methylation and hydroxymethylation, the result of epigenetic mechanisms.

In the current study, it is clear that such epigenetic changes in obese mice are linked to reduced amounts of the SIRT1 gene. This was the main reason of "decreased object location spatial memory in obese mice", according to HNGN.

"We feel this is a very exciting finding that identifies a new linkage between diet, epigenetics and cognitive function, especially in light of the burgeoning obesity epidemic in the U.S. and elsewhere," according to David Sweatt, corresponding author of the study, in a press release.

He added that it "offers a novel working model that may serve as a conceptual basis for the development of therapeutic interventions for obesity-induced memory impairment."

The study found a reduction in SIRT1 gene, as well as three other memory-associated genes, labelled as PPARGC1A, PPP1CB and RELN. They were all reduced in white mice that became obese due to 23 weeks of dieting. They also showed increased DNA methylation in their gene promotor regions, which was considered to be indicative of decreased gene expression.

As the changes took place over time, they suggested that the memory impairment due to obesity tends to take place with time. More research is needed to see if such epigenetic changes take place in obese humans or not.

The findings were published in the Jan. 27,2016 issue of The Journal of Neuroscience.