A gluten-free diet may help treat schizophrenia in some cases. During five weeks without gluten, patients who had elevated immunoglobulin G type antibodies (AGA IgG) improved in psychiatric and intestinal symptoms.
The treatment did not improve what are known as positive symptoms of schizophrenia, such as hallucinations. However, it significantly improved so-called negative symptoms, such as lack of motivation and inability to express emotion or experience pleasure.
“With a small population I thought we would see a mild effect. I was pleasantly surprised to see symptoms change dramatically in some of our patients,” said lead researcher Deanna Kelly, PharmD, director of treatment research at University of Maryland, Baltimore. She explained negative symptoms are arguably what hinder social functioning: “Some people can manage their voices and bizarre thoughts in a way that they can still work. But if you have no motivation and no social abilities then it becomes difficult to function.”
Kelly noted that anti-psychotic drugs target delusions but are relatively ineffective against negative symptoms.
In the blinded trial on a gluten-free diet, seven patients received 10 grams of gluten daily and seven patients received 10 grams of rice flour in a protein shake. At the beginning, no one was complaining largely about digestive problems such as abdominal pain and constipation. However, after five weeks the gluten-free group’s gastrointestinal symptom scores improved robustly. This benefit was unexpected, Kelly said.
Previous investigation suggested a link between inflammation and schizophrenia. Celiac disease, an autoimmune disorder triggered by gluten, affects about three percent of people with schizophrenia compared to one percent of the general population. However, one-third of those with schizophrenia have elevated AGA IgG. This is three times the prevalence in the healthy population. High AGA IgG is not normally found in celiac.
John Hopkins University research showed AGA IgG in schizophrenia may cross the blood-brain barrier, which normally protects the brain from antibodies. It could cause brain inflammation, which is observed in other conditions like multiple sclerosis and HIV.
Inflammation does not occur in all people with schizophrenia, suggesting it is a syndrome with various underlying causes. While a link with gluten has been discussed for decades, previous indiscriminate gluten-free trials may have obscured the benefits in the subgroup with high AGA IgG. The University of Maryland trial included only patients with elevated AGA IgG and excluded those with celiac.
“Schizophrenia is a rare but debilitating condition, and it is exciting to see any possibility for treatment,” said Shayna Coburn, PhD, psychologist at Children’s National Health System in Washington D.C., who did not work on the study. Coburn specializes in mental health for children with celiac but previously worked on schizophrenia research. “There is increasing interest on the possibility that a gluten-free diet might help certain people with mental illness, but we are still far from understanding whether this is true.
“This study is a great starting point, but it is still just a starting point,” Coburn added. “Should everyone with mental illness go on a gluten-free diet? I wouldn’t advise it just yet, given the stress and daily burden that it can create.”
Kelly said, “I’m surprised to see such a robust improvement and I’m hopeful that even in a sub-group of people this might be a potential treatment.”
