Inflammatory bowel disease linked to increased dementia risk

Last Updated: 2020-07-06

By Anne Harding

NEW YORK (Reuters Health) - People with inflammatory bowel disease (IBD) are more than twice as likely to develop dementia, especially Alzheimer's disease (AD), according to a new population-based cohort study.

IBD patients were also diagnosed with dementia about seven years earlier than controls, on average, Dr. Yen-Po Wang of Taipei Veterans General Hospital in Taipei, Taiwan, and colleagues report in Gut.

"We found an association between IBD and elevated risk for dementia, suggesting that patients with IBD may benefit from increased clinical vigilance and holistic medical care through a multidisciplinary approach," Dr. Wang told Reuters Health by email. "Early recognition and intervention will slow cognitive decline and improve the quality of life for patients and their loved ones."

Patients with ulcerative colitis (UC) or Crohn's disease (CD) may continue to have inflammation despite being in clinical remission, the authors note. They are also at increased risk of depression and anxiety, themselves independently linked to a greater likelihood of having IBD and worse outcomes from the disease. Recent research also found a higher risk of Parkinson's disease in IBD patients.

To investigate whether IBD might be associated with an increased risk of dementia, the authors followed 1,742 IBD patients 45 and older and 17,420 controls matched by sex, healthcare access, income and dementia-related comorbidities.

During follow-up, which lasted up to 16 years, 5.5% of the IBD group developed dementia, versus 1.4% of controls, for a significant hazard ratio of 2.54. Average age at dementia diagnosis was 76.24 years, vs. 83.45 for controls. There were no differences in risk between men and women or with CD vs. UC.

The increased risk was most pronounced for AD (1.9% of IBD patients vs. 0.2% of controls; HR, 6.19), but was also seen with vascular and unspecified dementia.

"Further research is needed to assess the effect of individual IBD medications on dementia. However, we hope our findings will lay the foundation to stimulate future research in the connection between IBD and dementia, and the development of novel intervention and therapeutics possibly leveraging the gut-brain axis," Dr. Wang said.

"IBD is a complex disease which causes a lot of suffering to patients," the researcher added. "We hope our findings will increase vigilance of dementia among elderly patients with IBD, leading to early detection and intervention through a multidisciplinary approach."

The findings are "not unexpected," given what is known about how chronic inflammation in the gut can affect the brain, and how glial cells in the brain are deactivated in response to inflammation, said Dr. Emeran A. Mayer, a professor at the G. Oppenheimer Center for Neurobiology of Stress and Resilience at UCLA.

"I was really glad to see this. This will be followed up by other studies hopefully," said Dr. Mayer, who did not participate in the study.

While the current treatment of IBD would not change based on the findings, there is growing evidence that anti-inflammatory diets, such as the plant-based Mediterranean diet, may reduce the risk of AD, Dr. Mayer added. "If I were a patient with ulcerative colitis, I'd definitely be on that diet," he said.

"This model of peripheral inflammatory signaling to the brain could affect other brain disorders as well," the researcher noted. If future research bears out the findings, he added, "this could really be a general mechanism to explain (brain-related) comorbidities in inflammatory bowel disease."

SOURCE: https://bit.ly/3dTG4Jg Gut, online June 23, 2020.