TABLE 2.
Summary of studies included in the analysis1
| Year | Authors (ref) | Title | Sample size | Length of GFD | Study design | Outcome of GFD |
|---|---|---|---|---|---|---|
| 1969 | Dohan et al. (20) | Relapsed schizophrenics: more rapid improvement on a milk- and cereal-free diet | 102 (102 M) | 175 d | Crossover, randomized | Faster release from locked to open ward with GFD. |
| 1973 | Dohan and Grasberger (21) | Relapsed schizophrenics: earlier discharge from the hospital after cereal free, milk free diet | 115 (115 M) | 175 d | Crossover, randomized | Faster release from locked to open ward with GFD. Gluten is pathogenic to those with schizophrenia. |
| 1976 | Singh and Kay (22) | Wheat gluten as a pathogenic factor in schizophrenia | 14 (3 M, 11 F) | 4 wk | Crossover | Gluten is pathogenic to those with schizophrenia. |
| 1981 | Potkin et al. (23) | Wheat gluten challenge in schizophrenic patients | 8 (5 M, 3 F) | 5 wk | Crossover, randomized | No effect. |
| 1982 | Storms et al. (24) | Effects of gluten on schizophrenics | 26 (26 M) | 10 d | RCT (n = 13 in each group) | No effect. |
| 1982 | Osborne et al. (25) | Lack of effect of a gluten-free diet on neuroleptic blood levels in schizophrenic patients | 5 (n/a) | 36 wk | Crossover | No effect. |
| 1986 | Vlissides et al. (26) | A double-blind gluten-free/gluten-load controlled trial in a secure ward population | 172 (10 M) | 14 wk | Crossover, double blind | Improvement in PIP with GFD. |
| 1990 | Reichelt et al. (27) | The effect of gluten-free diet on urinary peptide excretion and clinical state in schizophrenia | 10 (10 M) | 8 wk3 | Crossover, randomized; with an optional open-label extension | Improvement in NOSIE, CPRS, WIST scores with GFD. |
| 2012 | Jackson et al. (28) | A gluten-free diet in people with schizophrenia and anti-tissue transglutaminase or anti-gliadin antibodies | 2 (1 M, 1 F) | 2 wk | Open-label pilot | Improvement in BPRS scores, SANS, and in extrapyramidal symptoms. |
1BPRS, Brief Psychiatric Rating Scale (29); CPRS, Comprehensive Psychopathological Rating Scale (30); GFD, gluten-free diet; n/a, not available; NOSIE, Nurses’ Observation Scale for Inpatient Evaluation (31); PIP, Psychotic In-Patient Profile (32); RCT, randomized controlled trial; ref, reference; SANS, Scale for the Assessment of Negative Symptoms (33); WIST, Whitaker Index of Schizophrenic Thinking (34).
2A total of 22 ward patients were included, 16 with paranoid schizophrenia, and 1 with undifferentiated schizophrenia.
3In a subgroup of patients, a GFD was maintained for ≤56 wk.