Intestinal diseases can accelerate dementia

The study analyzed data from 111 patients with dementia who were subsequently diagnosed with IBD — ulcerative colitis or Crohn’s disease. Each of these patients was compared by gender, age, level of education, comorbidities, and type of dementia with five patients from the control group (534 people in total) who developed dementia without concomitant inflammatory bowel diseases.

The authors used the MMSE (Mini-Mental State Examination) scale, which is used to measure the degree of cognitive impairment. The average follow-up period was about four years.

In people with dementia and concomitant IBD, the level of cognitive decline was significantly higher: their MMSE scores worsened by 0.74 points per year more than in the control group. The difference persisted even after accounting for factors such as the type of dementia, other chronic diseases, medication intake, and education level.

In addition, there was a tendency for patients with dementia and IBD to have a higher risk of death during the follow-up period, although this association did not reach statistical significance.

According to the authors, accelerated cognitive decline may be associated with chronic inflammation characteristic of IBD. It is known that inflammatory processes in the body can cause neuroinflammation — the activation of immune cells in the brain, such as microglia, which in the long term can contribute to the death of neurons and accelerated deterioration of cognitive abilities.

The hypothesis of the involvement of the gut-brain axis, a biological mechanism linking the gut microbiota, the immune system, and the central nervous system, is also being considered. Microbiota disorders, which often accompany IBD, can have systemic effects, including changes in the permeability of the blood-brain barrier and activation of proinflammatory pathways.

Despite the limited number of IBD patients in the cohort, the results demonstrate the importance of considering inflammatory diseases when monitoring patients with dementia. According to the authors, a decrease of almost one MMSE point per year is a significant amount comparable to the effect of new drugs for the treatment of Alzheimer’s disease, such as monoclonal antibodies (for example, lecanemab).

“Our results highlight the need for a more personalized approach in the treatment of dementia patients, especially if they have concomitant inflammatory diseases. Such patients need more careful monitoring and, possibly, specific intervention strategies,” said the study’s lead author, Dr. Hong Xu.

In the future, scientists plan to conduct additional research involving a wider sample of patients to clarify the mechanisms of the relationship between inflammation in the intestine and neurodegenerative processes in the brain. In addition, it will be necessary to check whether IBD treatment — for example, immunomodulators or biologics — affects the rate of cognitive decline.