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Inflammatory bowel disease may accelerate the development of dementia
Last reviewed: 27.07.2025
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A new study from Karolinska Institutet demonstrates a link between inflammatory bowel disease and faster cognitive decline in patients with dementia.
The study, published in the journal Gut, points to the need for personalised treatments, the researchers say.
“Our findings suggest that inflammatory bowel disease (IBD) may impair cognitive function in people with dementia,” said lead author Hong Xu, associate professor in the Department of Neuroscience, Care and Society Sciences at Karolinska Institutet in Sweden. “This opens up opportunities for more effective care strategies with closer monitoring and targeted treatments, which will hopefully improve the quality of life of these people.”
The Gut Can Affect the Brain
Much has been written in recent years about the connection between the gastrointestinal tract and the brain. There are hypotheses that IBDs such as Crohn's disease or ulcerative colitis may contribute to dementia, but how exactly these diseases affect cognitive function remains a mystery.
In this study, researchers used the Swedish Cognitive Impairment and Dementia Registry (SveDem) to identify people who developed IBD after being diagnosed with dementia. The study included 111 people with dementia and newly diagnosed IBD. They were compared with 1,110 matched people with dementia but without IBD. The two groups were similar in age, sex, type of dementia, comorbidities, and current medication.
The researchers analyzed changes in the Mini-Mental State Examination (MMSE), a commonly used measure of cognitive function, over time and compared the rate of decline between the two groups. They also looked at how the MMSE scores changed in the first group before and after the IBD diagnosis.
Faster cognitive decline
People with dementia and IBD experienced faster cognitive decline, with worsening after IBD diagnosis than before. People with both diagnoses had almost 1 more point of decline in MMSE scores per year compared with people with dementia alone.
“This reduction is clinically significant and comparable to the difference between patients taking the new Alzheimer’s drug donanemab and those not taking it,” Dr. Xu said. “Further studies are needed to understand how inflammatory bowel disease affects the brain and whether treating IBD can slow cognitive decline.”
Because this was an observational study, cause and effect relationships could not be established. Additionally, the researchers had no data on the severity of the participants' IBD and only limited information on how exactly they were treated.