IgG antibodies to gliadin increased in bipolar disorder patients
MedWire News: Patients with bipolar disorder have increased levels of immunoglobulin (Ig)G antibodies to gliadin, but they do not display other antibody reactivity profiles that are indicative of celiac disease, say US researchers.
Writing in the journal Bipolar Disorders, Faith Dickerson (The Stanley Research Program at Sheppard Pratt, Baltimore, Maryland) and team explain that "increased immune sensitivity to dietary gluten proteins has been reported in schizophrenia but has not been studied in bipolar disorder."
To address this, the team recruited 102 patients (31% men) with the mood disorder and 173 mentally healthy controls (28% men) who were aged an average of 39.5 and 32.0 years, respectively.
Blood samples collected from the participants were assessed for levels of IgG and IgA antibodies to gliadin, IgG antibodies to deamidated gliadin, and IgG and IgA antibodies to tissue transglutaminase (tTG).
In unadjusted analyses, there were no significant differences in levels of these antibodies between bipolar patients and controls.
However, after accounting for factors such as age, gender, race, and maternal education, the researchers found that bipolar disorder patients were more likely to have higher levels of IgG antibodies to gliadin than controls.
Indeed, defining elevated antibody levels as equal to or greater than the 75th percentile of antibodies measured in the control population, the researchers found that bipolar disorder patients were 2.52 times more likely to have elevated levels of IgG antibodies to gliadin and 2.24 times more likely to have elevated levels of IgG antibodies to deamidated gliadin than controls.
There were no significant differences between the groups regarding adjusted levels of IgA antibodies to gliadin or IgA and IgG antibodies to tTG.
There were also no significant differences between bipolar patients and controls regarding the proportion of individuals who had deamidated gliadin or tTG antibody levels that were predictive of celiac disease.
Dickerson and team conclude: "Individuals with bipolar disorder have increased levels of IgG antibodies to gliadin. However, such antibody increase is not accompanied by an elevation in IgA antibodies to gliadin or the celiac disease-associated antibodies against deamidated gliadin and tTG."
Nevertheless, they add: "These results warrant further detailed examination of the molecular specificity and pattern of reactivity of the antibody response to gluten antigens in bipolar disorder."
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By Mark Cowen