Randomized controlled trial of a gluten-free diet in patients with schizophrenia positive for antigliadin antibodies (AGA IgG): a pilot feasibility study.
Study Goal
The researchers aimed to determine whether a gluten-free diet improves psychiatric, cognitive, and gastrointestinal symptoms in individuals with schizophrenia or schizoaffective disorder who have elevated anti-gliadin antibodies (AGA IgG).
Results Summary
Participants on the gluten-free diet showed improvements in negative symptoms and attention, as well as robust reductions in gastrointestinal adverse effects, compared to those on the gluten-containing diet. No significant improvements were observed in positive or global cognitive symptoms.
Population
Individuals with schizophrenia or schizoaffective disorder who had elevated AGA IgG but were negative for celiac disease.
Effective Dosage
10 g of gluten flour or rice flour daily via a shake.
Duration
5 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
gluten-free diet | decrease | Clinical Global Impressions scale | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | Cohen d = –0.75 | showed improvement | #1 |
gluten-free diet | decrease | negative symptoms | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | Cohen d = –0.53 | showed improvement | #2 |
gluten-free diet | no change | positive symptoms | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | - | noted no improvement | #3 |
gluten-free diet | no change | global cognitive symptoms | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | - | noted no improvement | #4 |
gluten-free diet | increase | attention | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | Cohen d = 0.60 | did observe an improvement | #5 |
gluten-free diet | decrease | gastrointestinal adverse effects | participants with schizophrenia or schizoaffective disorder who had elevated AGA IgG | - | robust improvements | #6 |
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.