People with inflammatory bowel disease might be vulnerable to developing dementia, a new study suggests.
Inflammatory bowel disease, or IBD, is an umbrella term for ulcerative colitis and Crohn's disease. Both cause chronic inflammation in the digestive tract, thought to be triggered by a misguided immune system attack.
In the new study of more than 19,000 adults, those with IBD were twice as likely to develop dementia over 16 years. They were also diagnosed seven years sooner, on average -- at age 76, versus 83 among people without IBD.
The findings do not prove IBD directly contributes to dementia, the researchers stressed.
One possibility is that certain lifestyle factors help explain the link, said lead researcher Dr. Bing Zhang, of the University of California, San Francisco.
He said future research should dig further -- looking, for example, at whether better control of IBD is tied to a lower dementia risk.
A bigger question, according to Zhang, is whether there is a role for the "gut-brain axis" -- which refers to the complex communication between the digestive system and the central nervous system.
Other research has found that IBD patients may have a higher risk of Parkinson's disease, another brain-based disorder. And there is lab evidence that metabolic byproducts churned out by gut bacteria can affect brain function.
It's also possible that the chronic, intermittent gut inflammation is, itself, underlying the IBD-dementia link, said Dr. Emeran Mayer. He is a professor at the University of California, Los Angeles School of Medicine and author of the book "The Mind-Gut Connection."
"I think the hypothesis that longstanding chronic gut inflammation contributes to neurodegenerative changes in the brain is very intriguing," Mayer said.
On the other hand, he added, lifestyle factors -- especially diet -- could potentially explain the higher dementia risk among people with IBD.
Zhang agreed, as the study lacked information on lifestyle factors such as diet and exercise.
The findings, published June 23 in the journal Gut, are based on medical records from 1,742 Taiwanese IBD patients aged 45 and up. Each patient was compared against 10 people who did not have IBD but were similar in other ways -- such as age, sex, income and other health conditions linked to dementia risk. Those included high blood pressure, diabetes and a history of stroke.
Overall, 5.5% of IBD patients were diagnosed with dementia over 16 years, versus 1.4% of the comparison group. After the researchers weighed other factors, IBD was still linked to a twofold higher risk of dementia.
Zhang said that if researchers can discover specific mechanisms that link IBD and dementia, that could potentially lead to new treatments someday.
For now, there are too many unanswered questions to give IBD patients specific advice on lowering dementia risk.
"The study was not able to identify a role of biologics or other medications underlying the increased risk," Mayer said. "It's not possible to make any recommendations regarding pharmacologic [drug] therapy."
He did, however, suggest some general steps people can take: Exercise regularly, address sources of chronic stress, and eat a healthy diet.
"In particular," Mayer said, "a largely plant-based diet, like the traditional Mediterranean diet, has been shown to reduce inflammatory markers in the circulation."
Another expert who wasn't part of the study noted that many IBD patients struggle with micronutrient and vitamin deficiencies.
"Because of the inflammatory nature of the disease and the role of the bowel in absorbing and/or retaining nutrients, patients with IBD often have micronutrients, vitamins and minerals deficiencies, including B12 and other B complex, vitamin D, as well as protein-calorie deficiency, that can all play a role in brain health and risk of dementia," said Dr. Aline Charabaty. She is director of the Inflammatory Bowel Diseases (IBD) Center at Sibley Memorial Hospital in Washington, D.C.
And she made another point: "Patients with IBD often restrict their diet or favor one food group over the other to manage their symptoms, which again can lead to nutrients deficit and imbalance, which can affect brain health," Charabaty added.
The Crohn's and Colitis Foundation has more on inflammatory bowel disease.