One of the biggest challenges in diagnosing and treating ADHD is trying to separate it out from other disorders that often present similar-looking symptoms. One such disorder is known as celiac disease. When gluten (a type of plant protein found in corn and wheat) is ingested in individuals with celiac disease, an inflammatory response in the upper portion of the small intestine occurs. When repeatedly challenged by gluten exposure, damage can occur to this portion of the digestive system, which leads to painful symptoms and impaired digestive and absorptive function.
Interestingly, celiac disease has also been linked to other neurological disorders such as depression and depressive-like symptoms. This may be due to poor absorption of the amino acid tryptophan (which is found in high concentrations in turkey, and is a big reason why turkey can make a person sleepy). Tryptophan is converted to another important agent in the body called serotonin, which is often found to be reduced in patients with depression and other related symptoms (sugar and milk can also give a temporary rise in serotonin levels, which is why ice cream and chocolate are often "comfort foods").
The good news to all this is that a gluten-free diet (which, unfortunately, can be very difficult to administer due to the prevalence of wheat in the Western diet) has been shown to ameliorate most of these negative symptoms. A study done on celiac disease patients and ADHD symptoms found that after treating patients with a gluten-free diet for 6 months, a number of ADHD-like symptoms subsided. The study used a method called Hypescheme, which is a type of computerized checklist used to quantify and analyze data involving ADHD and related disorders in a statistically significant fashion.
Statistically-significant improvements were seen in the following areas: attention to detail, duration of attention span, ability to complete tasks, distractibility, fidgety behavior, leaving a seat (when expected to remain seated), noisy disruptions and answering questions prematurely.
However, statistically significant improvements were not seen in other categories characteristic of ADHD. These include: losing/forgetting materials as well as restless and interruptive behaviors.
In previous posts, we have seen that certain treatments may be favorable for either inattentive ADHD type behaviors, hyperactive-impulsive ADHD behavior, or a combination of the two, called the ADHD Combined Subtype. It is interesting to note that the gluten-free diet results in improvements in characteristics that may be considered either "inattentive" (task completion, attention to detail, distractibility) or "hyperactive-impulsive" (fidgeting, noisy behavior and blurting out answers prematurely). While many studies on the possible connection between food additives and ADHD (see last paragraph of this post for more on this) seem to highlight the hyperactive side of the disorder, this celiac disease study seems to indicate a more mixed improvement across the whole spectrum of the disorder when a gluten-free diet is introduced.
Given the fact that many individuals who have celiac disease lack many of theoutward signs of digestive symptomsof the disorder, and the fact that there are so many potential overlapping factors between the symptoms of ADHD and celiac disease, it is quite possible that you or your child's ADHD may be a misdiagnosis of an underlying cause of celiac disease or a related disorder. I therefore strongly recommend individuals who are diagnosed with the disorder of ADHD (especially those who have had poor or adverse responses to previous treatments) to consider testing for celiac disease. This of course, is not meant to knock the competence of most physicians and other professionals, but rather a plea to eliminate a potentially common misdiagnosis through a relatively simple procedure. Several antibody-based tests can be used to detect celiac disease or related disorders with relative ease.
In general, there has been a lengthy debate over the connection between ADD and ADHD and food allergies. While previous studies had certainly performed, a landmark study was done in the mid 1970's by Dr. Benjamin Feingold which sought to link the relationship between food additives and food coloring and hyperactivity. Numerous studies have since followed on this topic, many of which have supported Feingold's hypothesis and many which have refuted it. As a result, a number of physicians began to recommend elimination diets in an attempt to control attention deficits and hyperactive behavior. We will be investigating the original Feingold article and summarize the effectiveness of these elimination diets in treating ADHD symptoms in the near future.
You mentioned the connection between celiac disease and mood disorders such as depression. In the article “Tryptophan Side Effects: L-Tryptophan Is Far From Harmless” (at http://www.supplements-and-health.com/tryptophan-side-effects.html) is discusses how tryptophan (and serotonin) actually decrease focus and attention, thus implicating these substances in ADHD and ADD.
Celiac disease leads to intestinal disturbances such as an increase in serotonin which is primarily found in the bowels. One of the results of the intestinal disruption by celiac disease is leaky intestinal walls. This leads to an increase of inflammatory serotonin in organs and tissues outside the bowels (i.e., the brain).