Background: Coeliac disease (CD) is increasingly prevalent and is associated with both gastrointestinal (GI) and extra-intestinal manifestations. Psychiatric disorders are amongst extra-intestinal manifestations proposed. The relationship between CD and such psychiatric disorders is not well recognised or understood. Aim: The aim of this systematic review and meta-analysis was to provide a greater understanding of the existing evidence and theories surrounding psychiatric manifestations of CD. Methodology: An online literature search using PubMed was conducted, the prevalence data for both CD and psychiatric disorders was extracted from eligible articles. Meta analyses on odds ratios were also performed. Results: A total of 37 articles were included in this review. A significant increase in risk was detected for autistic spectrum disorder (OR 1.53, 95% CI 1.24–1.88, p < 0.0001), attention deficit hyperactivity disorder (OR 1.39, 95% CI 1.18–1.63, p < 0.0001), depression (OR 2.17, 95% CI 2.17–11.15, p < 0.0001), anxiety (OR 6.03, 95% CI 2.22–16.35, p < 0.0001), and eating disorders (OR 1.62, 95% CI 1.37–1.91, p < 0.00001) amongst the CD population compared to healthy controls. No significant differences were found for bipolar disorder (OR 2.35, 95% CI 2.29–19.21, p = 0.43) or schizophrenia (OR 0.46, 95% CI 0.02–10.18, p = 0.62). Conclusion: CD is associated with an increased risk of depression, anxiety, eating disorders as well as ASD and ADHD. More research is required to investigate specific biological explanations as well as any effect of gluten free diet
