Genetic link between Alzheimer's and gut disorders confirmed

People with gut disorders may be at greater risk of developing Alzheimer’s disease (AD), according to a groundbreaking study from Edith Cowan University (ECU) that has confirmed a genetic link between the two. Previous observational studies have suggested a relationship between AD and gastrointestinal tract disorders, but what underpins these relationships was unclear — until now.

In what is claimed to be the first comprehensive assessment of the genetic relationship between AD and multiple gut disorders, researchers from ECU’s Centre for Precision Health analysed large sets of genetic data from AD and several gut-disorder studies — each of about 400,000 people. The team discovered people with AD and gut disorders have genes in common, with their results published in the journal Communications Biology.

“The study provides a novel insight into the genetics behind the observed co-occurrence of AD and gut disorders,” said research lead Dr Emmanuel Adewuyi.

“This improves our understanding of the causes of these conditions and identifies new targets to investigate to potentially detect the disease earlier and develop new treatments for both types of conditions.”

When the researchers conducted further analysis into the shared genetics, they found other important links between AD and gut disorders. For example, Adewuyi said abnormal levels of cholesterol were shown to be a risk for both AD and gut disorders.

“Looking at the genetic and biological characteristics common to AD and these gut disorders suggests a strong role for lipids metabolism, the immune system and cholesterol-lowering medications,” he said.

“Whilst further study is needed into the shared mechanisms between the conditions, there is evidence high cholesterol can transfer into the central nervous system, resulting in abnormal cholesterol metabolism in the brain.

“There is also evidence suggesting abnormal blood lipids may be caused or made worse by gut bacteria (H. pylori), all of which support the potential roles of abnormal lipids in AD and gut disorders.

“For example, elevated cholesterol in the brain has been linked to brain degeneration and subsequent cognitive impairment.”

The study’s findings suggest that cholesterol-lowering medications (statins) could be therapeutically beneficial in treating both AD and gut disorders. According to Adewuyi, “Evidence indicates statins have properties which help reduce inflammation, modulate immunity and protect the gut.”

Adewuyi did acknowledge that there is a need for more studies and that patients would need to be assessed individually to judge whether they would benefit from statin use. The research also indicated that diet could play a part in treating and preventing AD and gut disorders.

The study was supervised by Centre for Precision Health Director Professor Simon Laws, who said that while the research didn’t conclude that gut disorders cause AD or vice versa, the results are still immensely valuable.

“These findings provide further evidence to support the concept of the gut–brain axis — a two-way link between the brain’s cognitive and emotional centres and the functioning of the intestines,” Laws said.

Image credit: ©stock.adobe.com/au/fizkes

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