Gluten Free Diet & Depression

Scientific studies have reached wildly divergent conclusions about the possible connection between clinical depression and adverse reactions to gluten, proteins found in wheat, barley and rye. For example, a Harvard study found that people with the most extreme form of gluten intolerance, celiac disease, were no more likely to be depressed than healthy people. Other equally credible studies have upheld the oft-cited link and laid the blame on clinically quantifiable abnormalities in the brains of some gluten-intolerant people. Despite their differences, all sides agree that further research is needed.

Celiac Disease and Non-Celiac Gluten Intolerance

For a confirmed diagnosis of celiac disease, which affects about 1 percent of the population, three clinical criteria must be met: genetic predisposition, a positive antibody test and damage to the small intestine observable in biopsied tissue. If any of these factors are missing but patients still have adverse reactions to gluten, the condition is called non-celiac gluten intolerance, or NCGI. Even though NCGI is estimated to affect about 10 percent of the population, it still lacks a generally agreed-upon definition, so most studies into the effects of gluten intolerance only accept participants with celiac disease. For both disorders, adherence to a gluten-free diet is the only way to manage symptoms.

Symptoms of Clinical Depression

Intense sadness is a natural response to distressing circumstances, but when it lasts for more than two weeks and is accompanied by thoughts of suicide, sleep problems, anxiety and a general inability to think clearly or function efficiently, it becomes a medical problem. Like celiac disease, depression can run in families, suggesting a genetic link. Dysfunctions in regions of the brain connected to emotional response and cognitive function often have been identified in people suffering from clinical depression, but whether these abnormalities cause depression, or depression causes the abnormalities isn't always clear.

Gluten Intolerance, Brain Abnormalities and Depression

Some reputable studies seem to point so definitively to neuropathy, or brain dysfunction, as the cause of depression in people with celiac disease as to banish all doubt. One led by Cornell University and published in the May 2003 journal "Neurology" maintained that about 10 percent of celiacs experience depression, anxiety and other neurological complications. After reviewing case records of 20 such patients, researchers reported that gluten-free diets improved the conditions of some while others developed further problems. Another study conducted by the Mayo Clinic, along with several led by U.K. neurologist Marios Hadjivassiliou, have presented compelling evidence that gluten intolerance also can result in forms of neurological impairment even more debilitating than depression, including dementia, cognitive decline, loss of feeling in the extremities, movement disorders and epilepsy.

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Harvard Debunks Gluten-Depression Connection

A study led by Harvard Medical School's Celiac Center noted that previous research into the association between celiac disease, depression and other psychiatric disorders had yielded "conflicting results." Published on April 15, 2009, in "Alimentary Pharmacology and Therapeutics," the study concluded that at around 17 percent, there was no significant difference in the prevalence of depression among healthy people, celiacs and people with other gastrointestinal disorders. Of 1,000 participants, only those suffering from both celiac disease and type 1 diabetes, a genetically related autoimmune condition, were found to be at a substantially higher risk -- 37 percent -- of depression.