Randomized controlled trial of a gluten-free diet in patients with schizophrenia positive for antigliadin antibodies (AGA IgG): a pilot feasibility study

Abstract

Background: Approximately one-third of people with schizophrenia have elevated levels of anti-gliadin antibodies of the immunoglobulin G type (AGA IgG) — a higher rate than seen in healthy controls. We performed the first double-blind clinical trial of gluten-free versus gluten-containing diets in a subset of patients with schizophrenia who were positive for AGA IgG.

Methods: In this pilot feasibility study, 16 participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG (≥ 20 U) but were negative for celiac disease were admitted to an inpatient unit for a 5-week trial. All participants received standardized gluten-free meals and were randomized in a double-blind fashion to receive a shake containing 10 g of gluten flour or 10 g of rice flour each day. Participants were rated for psychiatric, cognitive and gastrointestinal symptoms at baseline and endpoint.

Results: Of the 16 participants, 14 completed the 5-week trial (2 discontinued early for administrative reasons). Compared with participants on the gluten-containing diet, participants on the gluten-free diet showed improvement on the Clinical Global Impressions scale (Cohen d = –0.75) and in negative symptoms (Cohen d = –0.53). We noted no improvement in positive or global cognitive symptoms, but did observe an improvement in attention favouring the gluten-free diet (Cohen d = 0.60). Robust improvements in gastrointestinal adverse effects occurred in the gluten-free group relative to the glutencontaining group. Adverse effects were similar between groups.

Limitations: This study was limited by its small sample size; larger studies are needed.

Conclusion: This feasibility study suggests that removal of gluten from the diet is associated with improvement in psychiatric and gastrointestinal symptoms in people with schizophrenia or schizoaffective disorder.

Trial registration: ClinicalTrials.gov NCT01927276.

Conflict of interest statement

D. Kelly served as an advisor to Lundbeck and HLS Therapeutics. A. Fasano is the founder and a stock holder of Alba Therapeutics. R. Buchanan served on the advisory boards for Astellas Pharma, Avanir, Boehringer Ingelheim-RCV, ITI, Inc., Lundbeck and Roche. He was a consultant for Takeda and Upsher-Smith Laboratories and on the DSMB for Pfizer. W. Carpenter has served as an advisor to Boehringer Ingelheim, Allergan, Health Analytics and Teva. All other authors have nothing to disclose.

© 2019 Joule Inc. or its licensors

Figures

Fig. 1

Participant flow diagram. AGA = antigliadin antibodies; IgG = immunoglobulin G; tTG = tissue transglutaminase.

Fig. 2

Change in SANS score by group (least squares mean). SANS = Scale for the Assessment of Negative Symptoms.