In the early days, up until the mid 1960s, it was generally believed that autism was a mental illness.
For the past 11 years, my colleagues and I have studied some 1200 autistic patients to determine if there were any underlying metabolic abnormality.
In our view, autism results from the action of peptides originating outside the body affecting neurotransmission within the central nervous system (CNS). We believe that these peptides result in effects which are basically opioid activity or that they may help to break down the opioid peptides which occur naturally within the CNS. In either case, the consequence is the same. The CNS neuroregulatory role, which is normally performed by the natural opioid peptides such as the enkephalins and endorphins, would be intensified to such an extent that normal processes within the CNS would be severely disrupted.
The presence of this intense opioid activity would result in a large number of the systems of the CNS being disrupted. Perception, cognition, emotions, mood and behaviour would all be affected. Higher executive functions would be disrupted, resulting in the diverse symptoms which constitute autism.
In our view, these peptides are derived from an incomplete breakdown of certain foods and, in particular, gluten from wheat and some other cereals such as barley, rye and oats and from casein from milk and dairy produce. It is also possible that other dietary sources could be implicated.
The reason for the increased levels of such peptides in the gut may be the inadequacy of the enzyme systems which are responsible for their breakdown. There may be genetically determined deficiencies of the required enzymes or shortages of the cofactors, such as vitamins and minerals required for the enzymes to function.
Normally the proteins lining the gut wall are sulphated, which forms a continuous protective layer over the surface of the gut wall. Where there is insufficient sulphation, the proteins clump together and the layer becomes discontinuous, which increases gut permeability.
The damage could also be physical, such as that caused by a surgical operation. Dr Andrew Wakefield of the Royal Free Hospital in London (Gastroenterology, 1995; 108: 776) demonstrated that the measles element of the combined measles, mumps and rubella (MMR) vaccine will produce fairly gross abnormalities of the gut wall. Recently (Lancet, 1998; 351: 637-641), the same team demonstrated very similar anatomical gut abnormalities (ileal lymphoid nodular hyperplasia) in a group of children with autism. It has been postulated that the attenuated strain of the measles virus, such as is used in vaccine manufacture, promotes an immune response which is insufficient to control the virus. Consequently, an attenuated "infection" becomes established in the intestines and produces the hyperplasia and an increased permeability of the intestinal wall.
Other environmental factors could exacerbate the process. Commonly, the autism becomes apparent only after the child has experienced a bout of encephalitis or meningitis.
Because the effects we see are the consequence of toxicity rather than allergy, in the vast majority of cases, allergy tests, which rely upon the presence of specific antibodies to casein or gluten, will prove negative or only minimally positive.
For many years, parents of children with autism have been investigating the effects of gluten and casein free diets diets. We have recently completed the pilot stage of a study involving the removal of gluten from the diet (Whiteley, "A Gluten Free Diet as an intervention for Autism and Associated Spectrum Disorders: a pilot study", 1997). Since the number of test subjects was comparatively small, caution must be exercised in making any conclusions, but there was a surprising consistency about the changes reported by both the teachers and the parents of the subjects.
The most consistent improvements appeared to be in the development of language and the ability to concentrate. Sleep patterns were also shown to improve in the majority. If anything, these improvements seemed to be more apparent in those subjects who are more seriously afflicted.
Many parents report an initial worsening in behaviour in a number of ways, and these may be explained in terms of withdrawal effects. The removal of foods which could result in the production of opioids could be predicted to produce effects akin to those seen when narcotic drugs are removed from an addict.
The anecdotal reports from parents are more than encouraging. We have personal knowledge of a number or cases where very young children have, apparently, shown very dramatic and rapid improvements. In over 50 per cent of our cases, doctors are sufficiently satisfied with the the observed results to prescribe gluten free products on the National Health Service.
Paul Shattock, OBE, is director of Autism Research Unit, University of Sunderland.