Those with bowel disorders are twice as likely to develop Alzheimer's.

The digestive system and the brain "are more connected than previously thought," to the point that those who suffer from persistent intestinal disorders are up to twice as likely to develop neurodegenerative diseases, such as Alzheimer's or Parkinson's , according to a study led by Spanish researcher Sara Bandrés-Ciga.

The researcher, director of the neurogenetics department at the Center for Alzheimer's and Other Dementias Research at the National Institutes of Health (NIH), co-directed this macro-study, which draws on three large databases: the UK BioBank and the biobanks of Scotland (SAIL Biobank) and Finland (FinnGen).

Their revolutionary findings were published this Wednesday in the scientific journal Science Advances , and were also contributed to by scientist Armando Reyes of the Spanish University of Malaga.

"The digestive system has its own 'second brain,' the enteric nervous system , capable of influencing the health of your main brain," Sara Bandres-Ciga explained in an interview with EFE.

Based on this knowledge, the Spanish scientist and her team have taken advantage of the enormous health database that has existed in the aforementioned biobanks since 2000 to explore the relationship between digestive disorders and neurodegeneration .

Researchers have considered some of the 155 metabolic, digestive, nutritional and endocrine diagnoses that have an impact on the gut-brain axis, including gastroenteritis , colitis or functional disorders such as irritable bowel syndrome , chronic constipation, chronic diarrhea, and abdominal pain and bloating.

They have also incorporated genetic and proteomic analysis into their characterizations, specifically genetic data from more than 487,000 people, and proteomic data from more than 52,000 people.

Their analysis has revealed that "the digestive system and the brain are more connected than previously thought, and that the health of the gut-brain axis directly influences the risk of neurodegeneration ," the researcher emphasized.

"Our data show that people with persistent gut disorders may be up to twice as likely to develop neurodegenerative diseases, such as Alzheimer's or Parkinson's , after the onset of gut-brain axis pathologies," he noted.

These correlations have been quantified and replicated at different time intervals, i.e., development of neurodegeneration at 5, 10 or 15 years.

Among the various intestinal diagnoses, researchers have found that people with non-infectious colitis, gastritis, and esophagitis had a higher rate of developing Alzheimer's or Parkinson's.

This relationship has also been observed in so-called functional bowel disorders, chronic conditions in which bowel function is altered without any obvious anatomical or metabolic disease.

They are usually conditions that cause abdominal pain, bloating, constipation, diarrhea or a combination of all these symptoms .

"We have seen that neurodegeneration doesn't depend solely on the brain: our digestive system is emerging as a key player in modulating the risk of developing Alzheimer's and Parkinson's," the researcher stated.

This implies, in his opinion, that "we must approach the study of neurodegenerative diseases from a systemic perspective, where neurodegeneration is not just a brain disease, but the result of an imbalance in multiple systems that interact through the gut-brain axis and other biological pathways ."

"Improving chronic gut disorders could reduce inflammation, metabolic imbalances, and microbiota alterations, all mechanisms we know influence brain function," he emphasized.

Bandrés-Ciga emphasized that "taking care of the gut can be an important preventative strategy," since, along with healthy lifestyle habits and controlling other risk factors, it could help reduce the likelihood of developing neurodegenerative diseases in the future.

Currently, it is estimated that more than 50 million people worldwide are living with dementia, with between 31 and 38 million suffering specifically from Alzheimer's disease and between 8.5 and 12 million from Parkinson's disease.

The study released today will contribute to the early identification of predictors of both diseases and improve early detection and treatment techniques . The authors have also developed an open, interactive resource to view the breakdown of comorbidities and the likelihood of both neurodegenerative diseases.