When you have attention deficit hyperactivity disorder (ADHD), you often behave impulsively and are easily distracted, and you probably have difficulty concentrating and focusing on important tasks. These problems can take a toll on everyday life — if you're a child with ADHD, your grades probably suffer, and if you're an adult, you may find it difficult to perform well at work or sustain a healthy relationship.
Up to 5% of preschoolers and school-age children suffer from ADHD. For many of them, symptoms will continue into adulthood. It's not clear exactly what causes ADHD; researchers believe it may involve a chemical imbalance in the brain or possibly even physical differences in brain structure. It is clear that it runs in families: If you have a close relative with ADHD, your chances of developing it yourself are up to five times greater than the regular population.
Parents have said for years that diet appears to play a role in their children's symptoms of ADHD, and many have removed food dyes and additives, along with sugar, from their children's plates in an effort to manage the condition. However, recent research is pointing to a new potential culprit for ADHD symptoms: gluten.
Celiac Disease, ADHD Linked in Studies
The evidence for an association between ADHD and celiac disease is strong: Children and adults with undiagnosed celiac disease have a much higher risk of ADHD than the general population.
In one study, researchers tested 67 people with ADHD for celiac disease. Study participants ranged in age from 7 to 42. A total of 15% tested positive for celiac disease. That's far higher than the incidence of celiac in the general population, which is about 1%.
Once they started on a gluten-free diet, the patients or their parents reported significant improvements in their behavior and functioning, and these improvements were backed up by ratings on a check list physicians use to monitor severity of ADHD symptoms.
Another study investigated the incidence of ADHD symptoms in people newly diagnosed with celiac disease. It looked at 132 participants, ranging from toddlers to adults, and reported that "ADHD symptomatology is markedly overrepresented among untreated celiac disease patients." Again, a gluten-free diet improved symptoms quickly and substantially — six months after starting the diet, most people had vastly improved ADHD symptoms.
Evidence Less Clear for ADHD and Gluten Sensitivity
Not everyone who has a problem with gluten has celiac disease — recent research has identified markers for non-celiac gluten sensitivity, which seems to involve a reaction to gluten but not the intestinal damage that characterizes celiac disease.
Gluten intolerance, or gluten sensitivity, may affect up to 8% of the population. For people with gluten intolerance, studies show it's possible that gluten plays a role in ADHD symptoms, but it's less clear how large a role it plays.
In one large study, researchers looked at the effects of the gluten-free, casein-free (GFCF) diet on people with various autism spectrum disorders. They reported a positive effect on ADHD symptoms, but noted that they couldn't say for certain that it came from the GFCF diet. They also couldn't say if the effect might have stemmed from removing gluten or from removing casein from the participants' diets.
Anecdotally, parents of children with ADHD have reported improvements in behavior (some quite significant) when they placed their children on special diets, including a gluten-free diet. However, it's difficult to correlate those improvements with the dietary changes.
Currently, there's no accepted test to detect gluten intolerance; the only way to know if you have it is if your symptoms (which usually involve digestive problems but also can involve neurological issues such as headaches) clear up when you go gluten-free.
Bottom Line: Go Gluten-Free or Not?
If you suspect gluten may be contributing to yours or your child's ADHD symptoms, what should you do?
First, you should consider testing for celiac disease, especially if you or your child shows other celiac-related symptoms. Remember, not all symptoms involve your digestive system; celiac symptoms in children may involve something more subtle, such as short stature or failure to thrive.
If the tests are negative for celiac disease (or if you decide not to pursue testing), you may want to discuss dropping gluten from your diet or your child's diet for a month or so to see if symptoms improve. To do this test properly, you'll need to avoid gluten completely, not just cut back on it. If the symptoms are influenced by gluten ingestion, you should notice a change within that month.
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Niederhofer H. Association of Attention-Deficit/Hyperactivity Disorder and Celiac Disease: A Brief Report. The Primary Care Companion for CNS Disorders. 2011; 13(3):PCC.10br01104.
Neiderhofer H. et al. A preliminary investigation of ADHD symptoms in persons with celiac disease. Journal of Attention Disorders. 2006 Nov;10(2):200-4.
Whiteley P. et al. The ScanBrit randomised, controlled, single-blind study of a gluten- and casein-free dietary intervention for children with autism spectrum disorders. Nutritional Neuroscience. 2010 Apr;13(2):87-100.