Before we go any further in this discussion, we must briefly review how ADHD is clinically diagnosed. Simply exhibiting hyperactive, inattentive or impulsive behavior does not necessarily qualify one as ADHD. One of the most common diagnostic tools for identifying the disorder in children is the Conner's Rating Scale (Please note that this link is to a commercial website which provides different versions of the test. It contains some good information about the nature of the different forms of the rating system, which is why I provided the link. This blogger declares no financial ties or commercial interests to this organization). There are multiple versions of this diagnostic test, but they all focus on scoring an individual on a numerical scale in a number of different areas such as inattention, hyperactivity, conduct issues, etc. Using this test as a diagnostic criteria, specific numerical cutoff scores (higher numerical scores indicate more ADHD symptoms) are used to help determine whether a child qualifies as being ADHD. In addition, there must be a persistence of these symptoms for at least 6 months in order for an accurate clinical diagnosis to occur. Of course, some subjectivity is involved in this process, since the rating scale is typically done by teachers, parents or other caregivers who may have internal biases as to whether they think the child has ADHD, but the overall accuracy and success of the test has been relatively well-documented. Keep in mind that there are other factors which trained professionals also use in making a diagnosis, but the Conner's rating scale scores often play a critical role in the process.
Returning to our topic of discussion, there has been relatively little research done on the actual mechanisms of the effect of food allergies on ADHD symptoms. However, there was a 1997 study done by Uhlig and coworkers which is of potential interest. This group studied the effects of food allergies on changes in brainwave frequencies throughout sixteen different regions of the brain. Note that we have discussed the topic of brainwave pattern differences in individuals with ADHD in an earlier post titled Genes and ADHD Brainwave Patterns. A summary of the components key findings of the study are listed below:
- Twelve children with known food allergies (not severe enough to pose a danger) had their brain wave patterns measured via EEG (electroencephalography) in sixteen different brain regions after both a 5 day period of consuming the allergy-provoking foods and a two-week period of avoiding these foods, and the results were compared between the two measurements.
- 10 of the 12 children had previously been tested and shown to have Conner's rating scale scores that were below the threshold for ADHD when the provoking foods were avoided and above the threshold when the foods were included in the diet. In other words, with all other things being equal, consumption allergy-provoking foods caused enough of a change in symptoms to push all twelve of the individuals over the threshold and into ADHD territory. A quick summary of the huge difference in most of the scores can be seen in the table below (note that the "cutoff" score for ADHD is 15 or above for the scale being used, these numbers are highlighted in black):
Note that significant changes in the Conner's rating scale were seen in all 12 children, and 10 of the 12 children's scores crossed the ADHD threshold score of 15 with regular consumption of provoking foods, including one who made a huge jump from 6 all the way up to 25. This shows how intolerance to specific foods can have a huge impact on Conner's rating scale scores and can easily push a child over the limit and can lead to an ADHD diagnosis. If these foods (with which the individual is often unaware of being provoking and a cause of an increase in ADHD symptoms) are consumed on a consistent basis, it is easy to see how 6 continuous months of symptoms can occur and lead to an ADHD diagnosis. While this is based on a small sample, and was not the main purpose of the study, these findings really do raise questions as to how many cases of ADHD arise simply from food-related intolerances, and can be changed by removal of the provoking foodstuffs from the diet (we will be investigating more on this topic in later blog posts).
- The most common foods provoking ADHD symptoms in the study were beet sugar, food colorings, wheat and milk.
- Frequencies corresponding to eight different brain wave states were obtained in 16 different regions of the brain. A summary of the numerical frequencies of these eight different states (in Hertz, or cycles per second) and their corresponding brain wave types and approximate brain activity levels are listed below:
- Out of all of the frequencies listed above, the beta-1 brainwave frequency was believed to be impacted the most by food allergies. Interestingly, it appears that the beta-1 brainwave frequency changes appeared to be concentrated the most in the right frontal and temporal regions of the brain (keep in mind that the different parts of the brain do not operate at uniform frequencies, for example, some regions may be in a predominantly beta-1 state while others are operating at a theta state). This area is also one of the brain regions most associated with ADHD, as we have seen in earlier posts. An outline of the areas with the greatest change in beta-1 activity is given in the diagram below:
The approximate locations of the 16 different brain regions probed for beta-1 brainwave frequency changes in the Uhlig study are given above (as one would see from a top-down view of the head). The larger blue squares indicate brain regions of greatest change in beta-1 activity between the two EEG scans (one after prolonged consumption and the other after prolonged avoidance of allergy-provoking foods). The smaller blue squares indicate regions of smaller (but still statistically significant) changes between the two EEG measurements. The white squares indicate brain regions that saw minimal change in beta-1 activity.We should also note that the brain regions most affected by food sensitivities also happen to be the same areas most connected to ADHD, as we have seen in previous posts, such as the one on differences in brain region blood flow patterns in ADHD.
- While the Uhlig study showed significant changes in beta-1 activity due to food-sensitivity effects, alpha activity changes were minimal. Other studies have indicated that diseases with reduced blood flow to the brain (which can include ADHD) are more associated with changes in delta and theta brainwave activities. As mentioned in the brainwave chart in this post, theta activity, which is essentially a daydreaming state, is (not surprisingly) seen more consistently in individuals with ADHD than in the general population. On another interesting note, adults with anxiety-type depression have also been shown to exhibit an increase in beta-1 activity in similar brain regions.
There are two key points we should take away from this article:
- Consumption of foods of which one may have an allergy or sensitivity to can have a huge effect on ADHD symptoms, as we saw from the Conner's rating scale score differences in this post. The fact that most children fell below the threshold score for ADHD when they avoided the provoking foods, but above it when they consistently consumed them should raise an alarm. While the ADHD/food allergy connection has been around for years, the sheer magnitude of the difference in scores (albeit from a smaller sample, which often will produce greater fluctuations in score differences because extreme individual cases stand out more). Of course not all ADHD cases are due to food allergies, but this study should lend credence to the potential effectiveness of eliminating specific foodstuffs (remember that beet sugar was the most common food sensitivity in the study) in treating at least some of the cases. Furthermore, monitoring for changes in beta-1 brainwaves, especially in the brain areas mentioned above via EEG may be an extremely effective tool of the future for diagnosing (and eventually treating) food-related ADHD symptoms.
- The pronounced changes in beta-1 activities highlight the surprisingly strong connection between the digestive system and the nervous system, as changes in conditions in the gut can result in extensive changes in neurological symptoms. We will discuss this connection in greater detail, as well as its implications on ADHD at a later time.