6.7 Biological treatments?
Evidence that biological influences play an important role in autistic spectrum disorders might suggest that the most effective therapies are biological. In practice therapeutic approaches targeted at biological functioning are particularly problematic. Genetic and neuropsychological influences in autism are not reversible, given the techniques of medical science available at the time of writing. Though studies in the field of molecular genetics have begun to offer provisional insights into which genes might be involved, there is no immediate prospect of interventions that could reverse these effects. In addition, we saw that influences at the biological level are only part of a complex causal and developmental process. An effective biological therapy would need to intervene in this process from a very early stage.
Despite the lack of therapies that address core biological influences, there are some important therapeutic interventions for symptoms that may accompany autism. Steffenburg's study, mentioned in Section 5, indicated that autism often occurs with epilepsy and/or may occur alongside another major medical syndrome that needs treating. Excessive hyperactivity and repetitive symptoms such as head banging need to be managed to avoid self-injury. While behavioural modification techniques described earlier are preferable, it may be necessary to prescribe drug treatments that influence brain function. One theory is that hyperactivity and repetitive behaviour are caused by the abnormal levels of the neurotransmitter called serotonin noted in some people with autism. A drug called fenfluramine, which reduces serotonin levels, has been quite effective in managing these symptoms. However, an earlier claim that it acts as a treatment for autism has, like other ‘miracle therapies’, been discredited.
This discussion would not be complete without mention of diet-based treatments for autistic spectrum disorders. A number of parents claim that special diets (especially those free of wheat-based or cow's milk-based products) alleviate their children's symptoms, and enhance their skills. However, sceptics (e.g. Rutter, 1999) argue that when such treatments are systematically evaluated, there is no evidence to support them. The theoretical rationale for such diets is not clear: the hypothetical effects of metabolic disorders on the brain (see Section 5), would occur early in development and would therefore not be reversed by a retrospective change of diet.
Consider such dietary approaches in light of the Box 11 criteria. Is there any theoretical rationale? Do anecdotal reports that they are effective in specific cases count as success? What ethical concerns might arise?
Since the discussion of dietary therapy given in this course is very limited, we can only tentatively apply the criteria in Box 11
Theoretical rationale: the causal mechanisms that might link a disorder of metabolism to an effect on brain function are unclear. Autism has an onset before 36 months of age, so any metabolic defect would have to be present at, or soon after, birth in order to affect developing brain function. Such a chain of events cannot be ruled out, but it cannot easily be verified, and it does not explain why a diet undertaken at a much later age should have any effect on autistic symptoms. The metabolic theory also appears incompatible with the large and robust body of evidence favouring other, particularly genetic, influences. Some researchers do claim, controversially, that it is genetic influences that render children vulnerable to metabolic disorders, which in turn cause autism. However, it is equally possible that metabolic defects are the resultrather than the cause of autism.
Methodological considerations: there is little doubt that some parents of children with ASDs find special diets of help in reducing some of their children's symptoms. The journal of the National Autistic Society, Communication, has featured reports from parents who endorse the use of special diets. Individual success stories such as these should not be rejected, but must be balanced against the reports of parents who do not find special diets helpful. Since these claims are contradictory, it cannot be ruled out that any beneficial effects are not directly due to changing the child's diet. More systematic studies have been inconclusive.
Ethics: the effects of dietary treatments are at most modest, and therefore ethical issues arise if any exaggerated claims are made for the success of therapy. In addition, since such diets often entail omitting a major source of protein, such as milk, or a major source of carbohydrate, such as wheat, there is the risk of exposing the child to a poorly balanced diet.