The different parts of our bodies are intricately tied together, and good health in one area can often mean benefits in other areas too. Take, for example, a potential link between a better education and a reduced risk of having gut disorders.
The research builds on a previous study by some members of the same team that uncovered a genetic association between Alzheimer's disease (where cognitive functioning breaks down) and gastrointestinal tract health problems.
"Gut disorders and Alzheimer's may not only share a common genetic predisposition but may be similarly influenced by genetic variations underpinning educational attainment," says geneticist Simon Laws, from Edith Cowan University in Australia.
The team pooled data from 766,345 people that had been involved in genome-wide association studies, looking at the relationships between Alzheimer's disease, specific cognitive traits, and a series of gut disorders.
Those gut disorders included peptic ulcer disease (PUD), gastritis-duodenitis, gastroesophageal reflux disease (GERD), irritable bowel syndrome, diverticulosis, and inflammatory bowel disease (IBD).
A "strong and highly significant inverse global genetic correlation" between cognitive traits and the majority of the gut disorders emerged from the analysis – but not for IBD.
The researchers think this link may depend on effects at specific parts of the genome. A gene-based analysis also found a significant genetic overlap of cognitive traits with Alzheimer's and gastro-intestinal disorders.
This relationship could even be relatively direct. By applying what's known as a Mendelian Randomization Analysis, the researchers showed it was highly possible factors like education and higher intelligence reduced the risk of certain gut disorders.
What's more, the team also found some evidence that GERD caused cognitive decline over several traits, including intelligence and educational qualification. This gut-brain relationship may indeed go both ways.
"GERD may be a risk factor for cognitive impairment, so it's important for health workers to look for signs or symptoms of cognitive dysfunction in patients presenting with the gut disorder," says geneticist Emmanuel Adewuyi, from Edith Cowan University.
We've seen numerous previous studies looking at the gut-brain axis and how it can be managed. For example, eating healthy foods can potentially reduce stress levels in the brain when a diet is properly managed.
Exactly how these relationships form isn't yet clear, but the connection between our brains and our digestive systems seems to be one of the strongest there is – and problems at one end of this chain can lead to problems at the other.
Findings from the research could influence government policies, the researchers suggest: the data shows that better levels of education and cognitive thinking are somehow influencing the chances of problems in the gut.
"The results support education as a possible avenue for reducing the risk of gut disorders by, for example, encouraging higher educational attainment or a possible increase in the length of schooling," says Adewuyi.
"Hence, policy efforts aimed at increasing educational attainment or cognitive training may contribute to a higher level of intelligence, which could lead to better health outcomes including a reduced risk of gut disorders."
The research has been published in the International Journal of Molecular Sciences.