Impaired cognitive function in Crohn's disease: Relationship to disease activity

Gerard Clarke, Paul J. Kennedy, John A. Groeger, Eamonn MM Quigley, Fergus Shanahan, John F. Cryan, Timothy G. Dinan

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Background & aims: Impaired attention and response inhibition have been reported in patients with Crohn's disease (CD) in clinical remission. Prospective studies are needed to determine whether this is a stable feature of CD and whether a similar impairment is evident in ulcerative colitis (UC). Thus, our aims were to examine whether patients with CD and UC exhibited a persistent impairment in attentional performance, and if this impairment was related to key biological indices of relevance to cognition. Methods: A prospective observational study was conducted on fifteen patients with CD and 7 with UC in clinical remission recruited from a specialty clinic and 30 healthy matched control participants. A neuropsychological assessment was carried out at baseline (visit 1) and at a 6 month follow-up (visit 2). Plasma proinflammatory cytokines, the plasma kynurenine:tryptophan (Kyn:Trp) ratio and the salivary cortisol awakening response (CAR) were also determined at each visit. Results: Across visits, patients with CD exhibited impaired attentional performance (p ​= 0.023). Plasma IL-6 (P ​= ​0.001) and the Kyn:Trp ratio (P ​= ​0.03) were consistently elevated and the CAR significantly blunted (P ​< ​0.05) in patients with CD. No significant relationships were identified between any biochemical parameter and altered cognitive performance. Conclusions: Impaired cognitive function is a stable feature of patients with CD. These data suggest that even where remission has been achieved, the functional impact of an organic gastrointestinal disorder on cognition is still evident. However, it is unclear at present if physiological changes due to disease activity play a role in cognitive impairment in CD.

Original languageEnglish (US)
Article number100093
JournalBrain, Behavior, and Immunity - Health
StatePublished - May 2020


  • Cognition
  • Crohn's disease
  • Gut-brain axis
  • Immune system
  • Inflammatory bowel disease
  • Tryptophan

ASJC Scopus subject areas

  • Nephrology


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