Inflammatory bowel disease linked to accelerated cognitive decline in individuals with dementia: a nationwide cohort study

A recent study by Erkert et al identified a new role for Alzheimer’s disease (AD)-associated presenilins as key molecules involved in maintaining intestinal epithelial function, barrier integrity and immune homeostasis, linking AD and inflammatory bowel disease (IBD) at the molecular level.1 2 Meanwhile, Zhang et al , from an epidemiological perspective, reported that individuals with IBD have a higher risk of developing dementia, particularly AD.3 The ‘gut-brain axis’, which links the intestine and the central nervous system (CNS), has received significant attention in recent years. IBD may impact brain function by triggering systemic inflammation, disrupting neuronal regulation and altering interactions between the gut microbiota and the CNS, potentially leading to dementia.4 5 However, whether IBD accelerates cognitive decline in dementia remains unclear. Dementia is an irreversible disease that worsens over time.6 Since dementia is currently incurable, slowing cognitive decline and understanding its mechanisms are crucial for improving the lives and healthcare support for affected individuals.7 We conducted a propensity score-matched cohort study to investigate the association between IBD and the progression of dementia, as measured by Mini-Mental State Examination (MMSE) scores. Using the Swedish Registry for Cognitive/Dementia Disorders (SveDem) and the Swedish National Patient Register, we identified individuals with dementia and incident IBD from 2007 to 2018. For each individual with dementia with later IBD, we matched 10 individuals with dementia without IBD using the nearest matching method and a calliper of 0.1 to balance confounders between the two groups. We defined …