Eaton,W. Mortensen, P.B., Agerbo, E. Byrne, M., Mors, O., Ewald, H. (2004) British Medical Journal 328 438-439
There is no abstract for this paper, but excerpts are provided here - and the full text can be accessed via the link given above.
Dohan proposed that an inherited defect interacting with an environmental trigger of gluten precipitated schizophrenia in some individuals, and provided supportive epidemiological evidence.1 Some clinical trials and case studies showed that a cereal free diet improved remission of symptoms of schizophrenia.2 The most important genetic marker found in the study of coeliac disease (6p23-p22.3)3 is very close to the dysbindin locus, which has been implicated in schizophrenia.4
The case sample comprised 7997 people older than 15 who were admitted to a Danish psychiatric facility for the first time between 1981 and 1998 with a diagnosis of schizophrenia and known maternal identity. For each case we randomly selected 25 controls from a subsample of all available controls, matched by year of birth and sex.
In a conditional logistic regression model the relation of risk factors for schizophrenia replicated that found in the literature.5 The univariate relative risk for schizophrenia, given coeliac disease, was 3.2 (P < 0.0001), unchanged by addition of the covariates (table). The adjusted relative risks for Crohn's disease and ulcerative colitis, when using the covariates discussed above, were both 1.4 (P < 0.08 for Crohn's disease, and P < 0.03 for ulcerative colitis). When coeliac disease and four additional cases of dermatitis herpetiformis were combined in an adjusted model as described above, the relative incidence for either of the two disorders compared with neither disorder was 3.1 (95% confidence interval 1.8 to 5.2)
A history of coeliac disease is a risk factor for schizophrenia, as shown in this epidemiological study. The risk relation is strong but reflects a small proportion of cases of either disorder, since both disorders are rare.
Removal of gluten from the diet is not dangerous or expensive and is an effective treatment for coeliac disease. Failure of replication in earlier clinical trials of gluten withdrawal may have been the result of sampling fluctuation since coeliac disease is rare. New screening tests for coeliac disease ar inexpensive and carry minimal risk and discomfort. An important question is the degree to which removal of gluten from the diet will alleviate symptoms in the small proportion of people with schizophrenia who screen positively for coeliac disease but do not show its classical symptoms
In addition, please see our factsheet on this topic: