Preliminary studies by Rosemary Waring, of the University of Birmingham, UK, suggests an enzyme deficiency in autistic children [Shattock has reported similar findings in children with ADD and ADHD.] This abnormality effects the sulfur-transferase system. With insufficient phenol sulfer-transferase (PST), individuals have an extremely low capacity to oxidize sulfur compounds. Children with this enzyme deficiency are unable to fully metabolize certain foods and chemicals that contain phenols and amines. PST is necessary to break down hormones, some food components and toxic chemicals that we encounter daily. If the enzyme is deficient, the body cannot detoxify the system--that is, it will be unable to render these substances harmless.
If this happens, harmful substances that should be metabolized (broken down) would build up to abnormal levels. These substances include serotonin, dopamine and noradrenaline. The children most likely to show this deficiency (based on her small sample size) showed normal development for the first 18 months to two years of life, and also show family histories of asthma, skin problems and migraine, as well as sensitivity to foods (especially wheat, milk and salicylates.) Many metabolic processes can be disturbed by phenolic compounds and cause many physical problems that may not have been previously thought connected to autism (excessive thirst, night sweating, facial flushing, reddened ears etc.)
There are some tests which can identify whether an individual has a weak detoxification pathway. However, normal levels of PST have not been established for children under the age of twelve. Dr. Waring has a test for children, which uses acetaminophen (Tylenol®) as a "probe" for finding weakness in this enzyme system. Testing does require a 24 hour urine collection, which can be a nearly insurmountable difficulty if the isn't reliably toilet trained. For more information Dr. Waring can be contacted at: The School of Biochemistry, University of Birmingham, Edgbaston, Birmingham, B152TT England. Dr. Waring doesn't currently have Internet access. Dr. Robert Sinaiko, a San Francisco specialist in Allergy and Immunology, is working on perfecting a test in this country. Hopefully, such a test will be available soon.
Unfortunately, there is not any standardized, recommended treatment for PST deficiency. Two approaches may be taken--you can try to increase the body's ability to detoxify itself, or you can try to decrease the toxic load to which you subject the system. Neither approach is 100% effective. To quote Developmental Delay Registry founder Kelly Dorfman:
Some parents have used diets that remove all known phenol components (such as Sara's Diet) to take the pressure off the PST-P system. While sometimes helpful, these diets are extraordinarily difficult to implement long-term, as naturally occurring phenols are in every food with color. Except in extreme cases, a diet reducing toxic load from the most concentrated sources...appears to be the best. That is...reduce juices (or limit to pear juice) and eliminate all artificial colors and flavors.
Unfortunately, no amount of intervention...can
totally unburden the PST-P enzymes....That is why it is critically important
to improve the efficiency of the faulty enzyme system while attempting to
lessen the load. Several nutrients may help. They include Vitamin C, reduced
L-glutathione and N-acetylcysteine. All of the antioxidants (including
selenium and bioflavanoids) are valuable for detoxification in general.
--from New Developments, Winter 96-97, a DDR publication.
Autism researchers have been intrigued by the fact that a PST deficiency can cause the improper metabolism of some neurotransmitters (serotonin, dopamine and noradrenaline.) It has been known for years that autistics often have abnormal levels of serotonin, at least as is measured in the blood. but the buildup of serotonin may be less significant than another outcome of PST deficiency--namely, the effect this deficiency would have on the permeability of the intestinal lining. One outcome of an improperly operating sulfur-transferase system is insufficient connective tissue in the gut wall. Thus, this deficiency could be yet another reason (besides Celiac Disease and other gastrointestinal ailments) that the gut wall would be "leaky." As stated above, when improperly metabolized proteins (such as gluten or casein) are able to escape the gut lining into the bloodstream, they can cross the protective blood-brain barrier.
I noted above that my son's urinary amino acid tests reveal a deficiency in eight amino acids. Five of these are sulfer-carrying amino acids. I am informed, by Dr. Baker, that this is a pattern he sees very frequently in autistic patients. Because the sulfur-carrying amino acids are involved in the detoxification of the body of both exogenous and endogenous pollutants, disturbances in these systems indicate disturbed immune systems. Considering how frequently these children suffer from numerous infections and allergies, this is not an unlikely assumption. In some parts of the country immunological approaches are being taken with some benefits to autistic children, and it is possible that for some the cause of autism may be an auto-immune disorder.
Though it cannot yet be proven, there is good evidence that a diet that eliminates gluten and or casein may indeed be beneficial. In an unpublished (1993) manuscript, Waring and Reichelt state "We think that the demonstrated peptides may be central to the aetiology of the disease. Exorphins not only increase social isolation in animal models, but may cause CNS inhibition of maturation." Another observation is equally intriguing: "...because most bioactive peptides are found in different chain lengths, but with very similar activity, different peptidase defects would cause similar but not identical symptom profiles and peptide profiles." They believe that this indicates that such "effector peptides" would be the "final common path of several clinical subtypes involving different lengths of peptides. It would also suggest that other diseases may show autistic symptoms if peptides are involved, as is seen for coeliac disease."