June 23 (UPI) -- Adults with inflammatory bowel disease are more than twice as likely to develop dementia than those without IBD, a study published Tuesday in the journal Gut found.
In addition, adults with IBD were diagnosed with dementia, on average, seven years earlier than those without the digestive disorder, the researchers found.
"The identification of increased dementia risk and earlier onset among patients with IBD suggest that [they] might benefit from education and increased clinical vigilance" to slow cognitive decline and improve quality of life," the authors wrote.
IBD is a group of digestive disorders that includes ulcerative colitis and Crohn's disease. As many as 3 million American adults have these conditions, according to the U.S. Centers for Disease Control and Prevention.
Meanwhile, roughly 6 million Americans are have some form of dementia, based on estimates from the Alzheimer's Association.
Evidence is mounting that communication between the gut, its resident bacteria -- also called the microbiome -- and the central nervous system is involved in various aspects of health and disease, the authors of the Gut study said.
This connection has been referred to as the "gut-brain axis."
While the cause of IBD is not clear, it is thought to develop from an impaired immune response to changes in the gut microbiome, the researchers said. In addition, recent research has linked the condition with another neurodegenerative disorder, Parkinson's disease.
For the Gut study, researchers analyzed data for 1,742 people 45 years old and older who were diagnosed with either ulcerative colitis or Crohn's disease between 1998 and 2011, and registered with the Taiwan National Health Insurance program, which was established in 1995 and is compulsory for all Taiwanese residents.
The researchers monitored participants' cognitive health for 16 years after diagnosis and compared it with that of 17,420 people who were matched for sex, age, access to healthcare, income and underlying health conditions, but who didn't have IBD.
During the study period, a larger proportion of those with IBD -- 5.5 percent -- developed dementia, including Alzheimer's disease, than those without IBD -- 1.5 percent -- the researchers found.
In addition, people with IBD were diagnosed with dementia at an average age of 76 years, compared to an average age of 83 years for those without IBD, the researchers said.
Those with IBD were six times as likely to develop Alzheimer's disease as were those without IBD, they said. The risk for dementia seemed to be associated with the length of time a person has IBD, they added.
Although the findings stop short of indicating a causal relationship between IBD and dementia, earlier studies have suggested that chronic inflammation and an imbalance in gut bacteria are potential contributors to cognitive decline, the researchers said.