People with a gut condition have double the risk of dementia than the general population, a new study has found.

And those with inflammatory bowel disease (IBD) – including ulcerative colitis and Crohn’s disease – are likely to be diagnosed with the condition earlier in their lives, researchers found.

The authors said there is increasing evidence supporting “reciprocal communication” between the gut and central nervous system in disease, termed the “gut-brain axis”.

Previous studies have found a link between IBD and Parkinson’s disease.

So the Taiwanese researchers set out to investigate the links between IBD and dementia.

Using a national Taiwanese database, 1,742 IBD patients were identified and compared with more than 17,000 people without this condition.

The participants were tracked for 16 years to see whether they developed dementia.

Just 1.4% of people in the control group went on to develop dementia compared with 5.5% of patients with IBD.

After taking account of potentially influential factors, including age and underlying conditions, people with IBD were more than twice as likely to develop dementia as those without.

Patients with IBD were diagnosed with dementia at 76 years old on average, compared with 83 years of age among the control group.

“We found increased risk of dementia following the diagnosis of IBD, with the average age of onset seven years younger compared with matched controls,” the authors wrote.

“Vigilance and education for dementia among elderly patients with IBD may improve early intervention to slow cognitive decline and improve quality of life.”

Commenting on the study, Dr Rosa Sancho, head of research at Alzheimer’s Research UK, said: “As surprising as it may be, current research suggests the gut and the brain are linked through what is termed the gut-brain axis.

“The brain doesn’t operate in isolation from the rest of the body and inflammation plays a role in the development of the diseases like Alzheimer’s that cause dementia.

“In this population-based study, researchers looked to see whether having a pre-existing inflammatory bowel condition affected a person’s dementia risk, but it did not look for the reasons underlying this. While this research suggests having inflammatory bowel disease increased the risk of dementia, further research is needed before we can be sure about cause and effect.

“A better understanding of the dementia risk in people with inflammatory bowel disease may help improve dementia diagnoses and get treatments to people who need them at the earliest opportunity. Only through research like this will we keep people connected to their families, their worlds and themselves for longer.”

Fiona Carragher, director of research at Alzheimer’s Society, said : “The role of gut health and the gut microbiome is currently a key focus in dementia research and, although the links to dementia and brain health are not yet well understood, it has been linked to other neurodegenerative disorders like Parkinson’s disease.

“As with every observational study, it’s impossible to know whether having inflammatory bowel disease directly increases our risk of getting dementia later in life. There are also many other factors that were not controlled in this study, including diet, exercise and elements of psychological health such as depression and anxiety, which could have played a role.

“If we can understand more about this complex relationship between brain and gut health, it could open up new approaches to tackling dementia, which affects 850,000 people in the UK.”