Can IBD Affect Memory and Thinking? A 2026 Systematic Review of 66 Studies Investigates

Many people living with inflammatory bowel disease describe a feeling of mental cloudiness: difficulty concentrating, forgetting words mid-sentence, struggling to stay focused. This experience, sometimes called "brain fog," has been widely reported by people with Crohn's disease and ulcerative colitis, but the underlying science has until recently been scattered across disparate research fields. A systematic review published in the Journal of Crohn's & Colitis in May 2026 has now brought those threads together, asking directly: does IBD play a role in cognitive decline? (Motisi Bertulli et al., J Crohn's Colitis, 2026)

What the Systematic Review Examined

The review team, led by Motisi Bertulli and colleagues, conducted a structured search of PubMed and Scopus databases through August 2024. They identified and analysed 66 studies spanning three research areas: population-based studies examining cognitive outcomes in people with IBD, genetic investigations looking at shared biological pathways, and preclinical (laboratory and animal) models exploring mechanisms (Motisi Bertulli et al., 2026).

The breadth of sources is significant. Population studies can show patterns across large groups of real patients, genetic approaches can identify whether IBD and cognitive vulnerability share underlying biological architecture, and preclinical models help researchers understand how inflammation might affect brain tissue, even if those findings cannot be directly applied to human clinical care without further study.

What the Evidence Shows About Cognitive Function in IBD

Across the body of studies reviewed, patients with IBD were found to exhibit potentially impaired cognitive function, with the areas most commonly affected being memory, attention, and executive processing (the set of mental skills involved in planning, organising, and flexible thinking) (Motisi Bertulli et al., 2026).

Three factors emerged as contributors to this pattern: disease activity, chronic inflammation, and psychological stress. This cluster is not entirely surprising. The NHS describes Crohn's disease as capable of causing wide-ranging complications beyond the gut; chronic inflammation affects multiple organ systems, and IBD is a condition with a significant psychological burden (NHS: Crohn's disease complications). What this review adds is a systematic look at whether these well-known features of IBD may have consequences for cognition specifically.

A Note on Study Types

It is important to read these findings with care. The 66 studies in this review include preclinical research (work done in laboratory settings or animal models) alongside population-based human studies. Preclinical evidence provides mechanistic hypotheses and helps explain how an effect might occur, but it cannot tell us how often or how severely cognitive changes occur in people with IBD in daily life.

The review authors themselves concluded that the current evidence base requires additional longitudinal studies and randomised trials to understand which, if any, IBD therapies have neuroprotective potential (Motisi Bertulli et al., 2026). This means the research points to a real and plausible phenomenon, but the scale, clinical significance, and reversibility of any cognitive effects in people with IBD are not yet fully characterised.

Treatments May Matter

One notable finding from the review is that certain treatments appeared to have a protective effect on cognitive outcomes. The review did not reach firm conclusions about which specific therapies are most beneficial; the authors call for randomised trials to clarify this, but the signal is meaningful. It suggests that controlling disease activity and inflammation, already the central aim of IBD treatment, may have benefits that extend beyond gut symptoms.

This is consistent with the broader understanding that well-managed IBD reduces the burden of systemic inflammation, which in turn reduces the range of potential extraintestinal effects.

What This Means for People Living with IBD

If you have IBD and have noticed changes in your mental sharpness, you are not imagining something unusual. The experience is real, and research is now actively investigating the biological reasons behind it. However, changes in memory, concentration, or clarity can have many causes, including medication side effects, disrupted sleep, anaemia, nutritional deficiencies, anxiety, and depression, and each of these is worth exploring with a clinician.

This systematic review does not mean that IBD inevitably causes cognitive decline. The research community is still working to understand whether the cognitive patterns observed in studies reflect a direct effect of IBD, a consequence of factors that commonly accompany IBD, or some combination of both.

If you have concerns about memory or concentration, speak with your doctor or GP. A clinical assessment is the appropriate first step, and it is the only way to identify what is happening in your specific situation. Do not adjust any IBD treatment on the basis of this article.