News and Notes about Scientific Research on Autism and other Developmental and Behavioral Disorders

Editor: Bill Ahearn, Ph.D., BCBA
Director of Research, The New England Center for Children

Why are more children being diagnosed with autism?

A study commissioned by the California State Legislature and conducted by the M.I.N.D. Institute (UC-Davis) was recently released on the website of the California Department of Developmental Services. This study reports that the number of individuals being diagnosed with an autism spectrum disorder (ASD) has increased exponentially in recent years in California(1). It is not known whether there is a true increase in the prevalence of autism or whether increased recognition of the disorder and improved diagnostic tools are providing more accurate estimates of the number of affected persons. To leave this question to the side for a moment, there is no debate about the impact of more persons being diagnosed with an ASD. More afflicted individuals means that more resources are needed to provide appropriate services. There are already more children with ASD who need effective, validated treatment delivered by qualified providers than there are individuals receiving such services.

In our previous Newsletter (Oct. 2002), a review of the literature on the prevalence and incidence of autism authored by Wing and Potter (2002) was presented. A few important points bear restating. First, it is likely the case that autism had been severely underdiagnosed until recently. Second, prevalence(2) estimates range greatly depending on the criteria used for assessing the presence of an autism spectrum disorder. Wing and Potter noted that estimates as high or higher than 6 per 1,000 have been obtained in large scale studies for ASD. This is much higher than the earliest estimates of the prevalence of autism as 2-4 per 10,000. Wing and Potter state that they feel that the increased prevalence is due to increased awareness of the disorder by the population at large as well as by physicians and other providers of service to children and better diagnostic tools that more accurately covers all of the autism spectrum. They also acknowledge that a true increase in prevalence cannot be ruled out and further research is needed to determine whether there is a true increase in the prevalence of autism.

It does seem unlikely that any increase in the prevalence of autism is due to the measles-mumps-rubella vaccine. Four studies (Taylor et al., 1999; Powell et al., 2000; Kaye et al., 2001; and Dales et al., 2001) conducted to respond to the suggestion that the MMR vaccine was related to autism, each found that the incidence(3) of autism rose on a yearly basis prior to and after the introduction of MMR. This was taken by each of these groups to emphatically assert that MMR was unrelated to autism because if it was, a sharper rise in incidence should have followed the introduction of MMR, and this was not observed.

Given the information outlined above, I would suggest that we do not have enough information to determine whether we currently have accurate estimates of the prevalence and incidence of autism. There are a number of researchers around the country looking at determining accurate measures of the prevalence and incidence of autism. In future research letters we will be reporting on the results of these studies. Regardless of the answer to this question, much time and energy will have to be focused on how to improve access to effective services for people with autism.

1 - The study has yet to be subjected to peer review, one of the necessary steps for determining the scientific merit of an investigation.
2 - The term prevalence refers to the number of individuals in a particular population who are afflicted with the condition being investigated. (Wing & Potter, 2002).
3 - The term incidence refers to the number of individuals in a specified population in whom the condition being studied begins within a specified time period (e.g., a calendar year). (Wing & Potter, 2002)

Dales, L. et al. (2001). Time trends in autism and in MMR immunization coverage in California.
Journal of the American Medical Association, 285, 1183-1185.

Kaye, J.A. et al. (2001). Mumps, measles, and rubella vaccine and incidence of autism recorded
by general practitioners: A time-trend analysis. British Medical Journal, 322, 460-463.

Powell et al. (2000). Changes in the incidence of childhood autism and other autistic spectrum
disorders in preschool children from two areas of the West Midlands. Developmental
Medicine and Child Neurology, 42, 624-628.

Taylor, B. et al. (1999). Autism and measles, mumps and rubella vaccine: No epidemiological
evidence for a causal association. Lancet, 353, 2026-2029.

Wing, L. & Potter, D. (2002). The epidemiology of autistic spectrum disorders: Is the
prevalence rising? Mental Retardation and Developmental Disabilities Research
Reviews, 8(3), 151-161.

World Health Organization can be found at: http://www.who.int

The effects of the media's coverage of the MMR controversy

Andrew Wakefield and his colleagues have made a number of claims that have not been supported by numerous experts and research. Most prominently, he and his colleagues reported in a published study that regressive autism and severe bowel problems were possibly associated with environmental factors (Wakefield et al., 1998). In the published article, the authors stated that their study did not prove a link between MMR and autism. However, after the study was published, Dr. Wakefield reported to the media that his study suggested a link and subsequently he has more strongly asserted the connection, has held press conferences to present unpublished research, and to claim that the UK released the MMR vaccine without properly testing it.

Wakefield's claims come in the face of mounting evidence (e.g., Fombonne and Chakrabarti, 2001; Black, Kaye and Jick, 2002; Taylor et al., 2002) that there is no association between MMR and autism. In fact, the Royal Free and University College Medical School, where Wakefield and colleagues conducted their work, had another research group (Taylor et al., 1999) that published a study, conducted at about the same time, contradicting the assertion made by Wakefield to the press. It is also not a judicious practice to present data in a public forum without it being peer reviewed and the unpublished data in question, though they are over 2 years old, have yet to be accepted for publication in a peer-reviewed outlet. To address the last assertion, two independent panels of experts were convened to investigate Wakefield's claim that the MMR was released prematurely in the UK. These panels both soundly rejected the claim.

In the Bulletin of the World Health Organization (Wise, 2001), it was reported the British government has had to spend over $4 million to combat the decreased usage of the MMR vaccine. The rate of MMR usage has dropped below 75% in certain areas in England and 95% coverage rates are necessary to prevent measles outbreaks. Japan, the only country that uses the single measles and rubella vaccines "suffers from endemic and epidemic measles. Between 1992 and 1997 there were 79 measles deaths in Japan" (Wise, 2001). The irresponsible statements by Dr. Wakefield and the sensationalism of this controversy have been costly in many ways and hopefully further damage will be stemmed by the dissemination of the sound research that has been conducted since 1998.

Brent Taylor and colleagues have reported one interesting and unsettling finding related to the impact of the MMR controversy. In Taylor et al. (2002), multiple parental interviews were obtained for many of the cases and a review of each individual case was made. It was found that several parents reported different times of the onset of autistic symptoms in different interviews. "A review of each record showed that in 13 children the history given by the parents had changed after the extensive publicity about MMR vaccine and autism. Before the publicity the parents often reported concerns early in their child's life, usually before their first birthday; the current history for the same children recorded symptoms as developing only after MMR vaccination, in some cases shortly after. This bias associated with changes in the history given by the parents necessitates particular care when interpreting [parental report]." (Taylor et al., 2002). In a follow-up study, Taylor and colleagues (Andrews et al., 2002) found that parents of children with autism diagnosed after the MMR controversy was publicized in the media were more likely to report the onset of autism as just after MMR vaccination than were parents of children with autism diagnosed before the controversy. The impact of the media's coverage of this issue is clear on at least one point, extraordinary claims are given more coverage than sound information based upon empirically valid and peer reviewed research.

Andrews et al. (2002). Recall bias, MMR, and autism. Archives of Disabled Children, 87, 493-494.

Black, C., Kaye,J., & Jick, H. (2002). Relation of childhood GI disorders to autism: Nested case-control study using data from the UK General Practice Research Database. British Medical Journal, 325, 429-421.

Fombonne, E. & Chakrabarti, S. (2001). No evidence for a new variant of measles-mumps-rubella-induced autism. Pediatrics, 108, E58.

Taylor, B. et al. (2002). MMR vaccination and bowel problems or developmental regression in children with autism: Population study. British Medical Journal, 324, 393-396.

Wakefield et al. (1998). Ileal-lymphoid-nodular hyperplasia, nonspecific colitis, and pervasive developmental disorder in children: An early report. Lancet, 351, 637-641.

Wise, J. (2001). Science vs "scaremongering" over the measles-mumps-rubella vaccine.
Bulletin of the World Health Organization, 79, (3).

Research at The New England Center

Editor's note: The New England Center for Children has recently added a researcher, Eileen Roscoe, as an Assistant Director in the Staff Intensive Unit. Eileen completed her Ph.D. with Brian Iwata at the University of Florida and then completed a post-doctoral fellowship at the Marcus Institute. Below is a brief description of her work.

Eileen Roscoe, Ph.D., BCBA
Assistant Director of Research, Staff Intensive Unit

I am excited to be a part of The New England Center for Children's excellent research program that prides itself on empirically demonstrating the effects of various assessment and treatment procedures for children with autism. Previously I conducted research on the assessment and treatment of problem behavior (self-injurious behavior and stereotypy) maintained by automatic reinforcement(1). In one study, I compared the effects of two treatment procedures, noncontingent reinforcement (NCR) and sensory extinction (EXT), for individuals whose problem behavior was not maintained by social reinforcement (i.e., their behavior was maintained by sensory stimulation or automatic reinforcement). In the NCR condition, participants had continuous access to a highly preferred item, however, in the EXT condition, participants wore protective equipment (gloves or protective sleeves) that may have made the sensory stimulation directly produced by their behavior less reinforcing. Although both procedures reduced the targeted problem behavior, NCR was associated with either more rapid or greater overall response suppression.

Another project I worked on was a large-scale study of chronic hand mouthing(2). The first study was both a descriptive and experimental analysis in which I documented the frequency, severity, and functions of hand mouthing among a large population. A second study evaluated a progressive series of treatments aimed at reducing hand mouthing maintained by automatic reinforcement and increasing appropriate leisure interaction. Stimulus preference assessments, similar to some of the assessments used here at NECC, were conducted to identify items that would most effectively compete with the participants' hand mouthing as well as items that might be used to shape appropriate behavior in the place of hand mouthing. The results indicated that all participants were successfully treated by one of the interventions used in the study.

My current research interests are similar to those mentioned above (i.e., automatic reinforcement, functional analysis, NCR, and stimulus preference assessments). I am excited about the opportunity I have been given here at NECC, and I look forward to working on a number of clinically-based research projects in these areas.

1 - Editor's note. The term automatic reinforcement refers to behavior thought to be maintained the sensory consequences of that behavior.
2 - Editor's note. Hand mouthing is form of self-injurious behavior that can be very difficult to treat.

Recent Research on Preference and Reinforcement at NECC

Over the past 7 or 8 years, individuals from NECC have been conducting research on preference and reinforcement. In order to decrease challenging behavior and teach new skills, we need effective reinforcers. Yet, many special educators seem take reinforcement for granted. At NECC, not only do we pay a great deal of attention to identifying the preferences of the children we work with, we are trying to develop more effective and efficient ways to do this, and to disseminate this information to others.

A recently completed survey found that most practitioners working with children with special needs who can speak, identified potential reinforcers simply by asking the children what they liked. In fact, 99% of special educators in public schools said that this was the only technique they used to identify potential reinforcers. Is this a problem? For some children with disabilities, the answer could be, "Yes". Research conducted at NECC has demonstrated that in about 30% of cases, children's verbal reporting did not accurately identify effective reinforcers. This is certainly important information to disseminate because one reason that children may make slow progress is that effective reinforcers are not being used. Currently, our research is focusing on identifying the prerequisite skills for conducting preference assessments that involve using a child's verbal report.

For children who use PECS or other icon-based communication systems, we have also been exploring whether or not pictures can be used to identify effective reinforcers in children with special needs. In most cases, we have found that pictorial preference assessments can indeed identify effective reinforcers. Again, our current research focuses on identifying the prerequisite skills for conducting these types of preference assessments. We have also been conducting a series of studies to look at the question of how often preferences change in our students. This would determine how often formal preference assessments should be conducted, an important question not yet answered by our field. Overall, we found that preferences for general categories of edible items (e.g., chocolate items, salty/crunchy foods, fruits/vegetables) remained relatively stable over a 1-year period of time.

Why should we pay so much attention to reinforcement? Why is it so important to identify effective reinforcers? Because for some children with severe disabilities, there may be little learning without them. In some cases, children with disabilities may make progress just as fast as their typical peers, without any programmed reinforcement being needed. Obviously, this is ideal. The reality, however, is that some children with special needs learn more slowly than others, and may need some extra reinforcement in order to learn.

Web Resources

For information about the New England Center, visit our Web site www.necc.org.

For information about autism, visit the National Library of Medicine's autism site www.nlm.nih.gov/medlineplus/autism.html.

For information about applied behavior analysis in the treatment for autism visit www.behavior.org.

For science-based information on biomedical treatments and theories in autism visit www.autism-biomed.org.

For professionally-screened information on health care (including some treatments for autism and other developmental disabilities), visit www.quackwatch.com.



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