Dr Jennifer Cunningham diagnoses the problem with fashionable new 'cures' for autism
All parents anticipate the fascination of watching their children grow up and develop, and sharing their excitement and sense of achievement as they play, make discoveries and master new skills. So imagine the devastation experienced by the parents of autistic children as they realise they will enjoy very few of these pleasures, and that their children's severe behaviour problems and learning difficulties will seriously disrupt the lives of all members of the family for the indefinite future.
The diagnosis of autism is agonising news, made worse by the uncertainty surrounding the condition. We know that autism is an organic brain disorder and that there is a genetic contribution to its development, but there is no diagnostic medical test (blood test, genetic marker or brain scan) available. The diagnosis has to be made on the basis of behavioural or psychological features. Autistic children must show a number of deficits or abnormalities, before the age of three, in the areas of social interaction, social communication and imagination. They must also display aberrant behaviours such as stereotyped and restricted interests, adherence to routines and rituals, preoccupation with parts of toys and repetitive hand or body movements. Once the diagnosis has been made, parents must contend with the fact that medical research is not yet sufficiently advanced to offer rational treatments. Trials of various psychoactive drugs have been disappointing or inconclusive. There is evidence that very structured, behaviourally orientated teaching programmes are most effective in improving children's social interaction, play and language development, as well as decreasing their obsessive, ritualistic behaviour. But the scope of these interventions remains very restricted.
Unless parents gain a realistic appreciation of their child's long-term difficulties, they are liable to exhaust their emotional and financial resources chasing after every new therapy or theory, however poorly substantiated scientifically, in search of a 'cure'. But in the past two years, several theories about autism have received unprecedented media attention (and sent parents off on just such a chase).
First was the theory that the combined measles, mumps and rubella (MMR) vaccine causes an inflammatory bowel condition and autism. Then a gut hormone, secretin, was discovered which, it has been asserted, reverses the symptoms of autism. Similar claims have been made for diets that exclude gluten (wheat) and milk products. Paediatricians and GPs have been inundated with requests to refer children to gastro-enterologists, to prescribe gluten- and milk-free diets and to endorse secretin injections. Most of those working with autistic children have been loath to comply with such requests because of the lack of scientific evidence for these theories. But many parents have disregarded our reservations, put their children on to these diets and taken them (often at great expense) to those practitioners prepared to administer secretin injections.
The perception now exists among parents, encouraged by the media's coverage of these issues, that most of us working in this field are part of a conservative and intransigent medical establishment. We are prepared to defend vaccination campaigns even if they put some children at risk of autism, yet we are not prepared to accept new medical theories and treatments that could help relieve the symptoms of autism. The researchers who propound these theories and the doctors administering these treatments, by contrast, are regarded as courageous pioneers battling against official indifference and dogma. Dr Andrew Wakefield, the gastro-enterologist whose study linked MMR vaccination to a new form of inflammatory bowel disease and autism (reported in the Lancet, 28 February 1998), has insisted that he has acted out of a sense of moral duty to his patients. 'If there are children who are damaged by these preventive measures they have to be listened to, investigated and treated. I know it makes it difficult for the public health doctors but there is nothing to be done about it.' (Independent, 27 February 1998)
But even if Andrew Wakefield is intrepid, that does not exempt him from the exacting requirements of credible scientific research. His research team at the Royal Free Hospital, London, produced an earlier study in 1994 that suggested that measles or measles vaccine virus are implicated in the inflammatory bowel disorder Crohn's disease. These results have not been replicated by other researchers and the theory is now discredited (see the British Medical Journal (BMJ), 17 January 1998). In fact, Wakefield's study of autistic children did not find any evidence of measles vaccine virus in any of their tissues - making the theory of MMR vaccine damage entirely circumstantial and speculative. Hundreds of millions of people worldwide have received measles-containing vaccines since the mid-1960s without developing chronic bowel problems or autistic disorders. National data in Britain indicate a rise in the incidence of autism, but it started over a decade before MMR vaccination was introduced in 1988 and it showed no change at that time (BMJ, 7 March 1998). Even if one accepted that some autistic children have an associated form of inflammatory bowel disease (and most gastro-enterologists refute this), it does not mean that it is causally related to autism. In Wakefield's study the behavioural changes postulated to result from malabsorption in the bowel and consequent neurological damage preceded the bowel symptoms in nearly all their reported cases.
Nonetheless, Wakefield's postulate has been tied in with theories about secretin. Secretin is a hormone produced in the small bowel that acts on the pancreas, leading to the release of water, bicarbonate and enzymes. These enzymes break down proteins into polypeptides and then into amino acids, which are absorbed through the gut wall into the bloodstream. A test dose of secretin is sometimes given to patients being investigated for gastrointestinal problems, to assess pancreatic function. After such a test dose was administered to an American child with autism, Parker Tucker, in 1996, his parents reported a dramatic improvement in his behaviour, eye contact and speech. This set in train an avalanche of demands for secretin injections from parents in the USA, and was repeated in Britain two years later. The theory is that autistic children have low levels of secretin which result in inadequate digestion of proteins, especially gluten and casein in milk, and the subsequent absorption of polypeptides through a 'leaky' bowel (this is where Wakefield's theory comes in). These 'toxic' polypeptides or opioids, it is argued, bind to morphine-like receptors in the brain and disrupt normal neurological transmissions.
Whether one regards this theory as elegant or contrived, it remains unsubstantiated. Reports of the efficacy of secretin are largely anecdotal. Three trials in the USA comparing the effects of secretin with a placebo injection of saline found no difference in children's behaviour between the two groups. Two Taiwanese trials reported that secretin improved some of the symptoms of autism, but the validity of the results has been strongly contested. What is more alarming than this lack of evidence is that secretin has neither undergone safety trials nor been licensed for use in children in either Britain or the USA. We do not know whether it is safe to give children repeated doses of secretin injections or if it will have any long-term effects on children's health and growth.
So why have these theories taken off among parents? When I became part of an autism assessment team five years ago, parents were just as desperate as parents are today to find the cause of their children's condition, and a cure - although I do not believe they would have subjected their children to unregulated trials of an unlicensed drug. But now parents, like researchers and doctors, are influenced by a very different set of social attitudes and trends. There is currently a widespread cynicism about modern medicine, and a move away from it towards alternative medicine and therapies. Parallel with this is a growing indifference to scientific method and an acceptance of less rational (religious or mystical), and more subjective, justifications for treatments or therapies. Then there is the perception that modern society has produced an increasingly polluted and toxic environment, resulting in an increased risk of serious allergies, antibiotic-resistant infections and genetic damage, among other dangers. In such a climate it is hardly surprising that people begin to fear the very things that helped to conquer disease in the twentieth century, such as antibiotics and immunisations.
But probably the most important contemporary trend is the development of a culture where people are encouraged to see themselves as the victims of harmful external agents or culpable agencies. Such a culture cannot accept that accidents - in nature just as in social life - are just that, unintended and coincidental. Instead, people are driven to look for something or somebody to blame when things go wrong, be it a natural disaster or a genetic abnormality. Under these circumstances it is easy to see why the parents of autistic children are so susceptible to scares about MMR vaccination or the food their children eat. We can appreciate why they are hostile to the medical establishment and turn to professionals who are prepared to accommodate to their frantic quest. But they do so at the cost of abandoning medical standards of safety and scientific standards of proof.
What is autism?
Autism is a severe, lifelong neurodevelopmental disorder of social communication. We now know that it is the result of structural or functional abnormalities in the brain, arising during brain development (probably in early embryogenesis) and impacting on children's intellectual, social and emotional development. The abnormalities appear to involve the 'motivating' parts of the brain: those involved in the control of attention and the perceptual guidance of action and those involved in the patterning and communication of emotion. But the impact of these abnormalities on a child's development often does not become apparent until the second year, by which time autistic children frequently show problems in their social development.
What is meant by social communication? The most obvious prerequisite for effective communication is language. Another essential component of communication is the interaction between persons, involving the sharing of ideas and emotions. It is in terms of their lack of responsiveness to other people that autistic children's development is most strikingly deviant.
Babies come into the world pre-programmed to respond to social stimuli and form attachments to carers. By nine months, infants begin to show two extremely important behaviours. They show joint attention: sharing their experiences of objects or actions with others and monitoring the emotional responses of adults, such as responding to tone of voice, and pointing to things they find interesting to draw other people's attention to them. This is a major developmental step, indicating a sense of self and other Secondly, they look at people's faces for information, a practice known as social referencing. Infants and toddlers look at their carers' faces and by picking up the emotional signals they will decide on their action. When they receive encouraging or positive signals they will approach and engage with an object or situation; when the signals are anxious or negative they will retreat. Joint attention and social referencing allow children to learn through other people about how to respond to experiences, both behaviourally and emotionally.
Autistic children are usually very focused on their own activity and show no desire to share their experiences. They seldom imitate other people's actions, rarely follow the gaze or pointing gestures of others, and fail to look at adults' faces and use the emotional display to guide their behaviour. Nor do they point at interesting things. This lack of joint attention and social referencing both impairs the child's judgement about situations and impairs their understanding of emotions and relationships with others. The fact that autistic children do not see situations from other people's perspective will have profound and cumulative effects on their cultural learning and social relationships.
Reproduced from LM issue 128, March 2000