Autism Biomedical Information Network

Early screening, interventions key to improving autism outcomes

by Chris P. Johnson, M.Ed., M.D., FAAP,
Marshalynn Yeargin-Allsopp, M.D., FAAP,
and Philip R. Ziring, M.D., FAAP

"My son Alexander is 11 years old. It was not until he was about 4 years old that I ceased thinking that he was 'just like me' ? bull-headed and slow-to-speak as a toddler, disruptive and inconsiderate in grade school ? and accepted his diagnosis ... ."

Clarence Schutt, a Princeton professor and father
of a child with autism
(from NAARRATIVE, newsletter of the National Alliance for Autism Research, 1997)

Autism spectrum disorders (ASD) are a collection of neurologically based developmental disorders characterized by impaired social interaction, impaired verbal and nonverbal communication, and abnormal, restricted, stereotyped behaviors.

ASD is the umbrella term for several conditions that have deficits in social skills as their hallmark. The term generally refers to autistic disorder, pervasive developmental disorder ? not otherwise specified (atypical autism) and Asperger syndrome.

For most children, the cause of autism is not known; however, a biological basis for the disorder is now well-accepted. A meeting of experts convened by the National Institutes of Health (1995) concluded that autism is indeed a genetic condition (Bristol, Volkmar, 1996). Yet the lack of a clearly defined mechanism to explain autism has led to many theories of causation.

While it is now well-accepted that autism has strong genetic underpinnings, there is recent evidence that environmental factors also may play a role, as demonstrated best by the increased frequency of autistic behaviors in children of mothers who ingested thalidomide during pregnancy.

Diagnosing a child with ASD presents the pediatrician with a challenging task since there is no biological marker. Instead, diagnosis must be based on the presence or absence of a constellation of symptoms and behaviors consistent with DSM-IV criteria. Judgment regarding the presence or absence of these behaviors is somewhat subjective and depends on the clinician's training and experience with ASD.

By definition, the onset of symptoms must occur before the third birthday. Even more challenging is disentangling the "age of onset" from the "age of recognition" (Volkmar, et al., 1985). Although most children later diagnosed as ASD present during the second year, a careful history often will reveal onset of some autistic features within the first year of life.

In fact, retrospective studies of home videos of infants have revealed that 8- to 12-month-olds with autism could be distinguished from normal infants by deficits in four areas: decreased eye contact, orienting to name, pointing and showing (Baranek, 1999; Osterling and Dawson, 1994; Mars, Mauk and Dowrick, 1998).

In about one-fourth of cases, parents report that development was normal until age 15 months to 24 months, after which the child lost previously acquired speech, withdrew socially and became indifferent to his/her surroundings (Tuchman and Rapin, 1997).

Autism characterized by such regression during the second year of life when children typically receive immunizations, particularly the measles, mumps and rubella vaccine (MMR), has led recently to concern about a possible link between the vaccine and ASD. In addition, there have been questions related to whether routine childhood immunizations can be at least partly responsible for what is now thought to be a higher prevalence of autism than previously reported in the scientific literature.

One of the major reasons used to point to a possible causal relationship is the recent increase in the number of required vaccines for young children. However, as noted above, the timing of administration of most of these vaccines coincides with the pattern of onset of behaviors typically seen in autism.

Concern about a possible link between autism and childhood immunizations is the most controversial and contentious of the many autism issues facing parents, physicians, researchers and the general public. If indeed there could be a link between autism and vaccinations, we must not hesitate to find out; as physicians, we all practice by the motto, "Primum non nocere."

Attention to the autism/MMR vaccine controversy initially was generated by a 1998 Lancet article by Andrew Wakefield, M.D., describing a case series of 12 children with autism or other developmental disabilities who had been referred to the author's gastroenterology clinic because of chronic bowel problems. Eight of the 12 children were described by their parents as having onset of autistic behaviors after receiving MMR vaccine.

An editorial that appeared in the same issue pointed out major limitations in drawing causal inferences from the case series, i.e., small number of cases, biased case ascertainment, lack of a control group, autistic behaviors preceded the bowel symptoms in most cases and lack of a clear case definition.

To date, there is no convincing evidence that any vaccine can cause autism or any kind of behavioral disorder. The current biologic and epidemiologic evidence indicates that vaccines (including MMR) are not likely to be causally related to development of autism. Additional research is in progress specifically to evaluate the association between vaccines and autism in a U.S. population. Other relevant research also is well under way that may yield clues to underlying etiology, such as genetics, immunology and language and communication characteristics.

In the meantime, screening young infants and early referral of those considered at risk for this condition is extremely important. It has been found that parents' concerns are reliable indicators that a problem exists (Glascoe, 1997). Pediatricians are strongly advised to listen to the parents, value their concerns and take appropriate action, which includes, but is not limited to, prompt referral to:

  • a specialist who is knowledgeable about ASD,
  • an audiologist for a hearing evaluation, and
  • an early intervention program.
Realizing that some parents may be unaware of their infant's or child's developmental delays and atypical behavior, it is critical that clinicians maintain a high index of suspicion during developmental surveillance at every well-child encounter, especially prior to age 12 months or shortly thereafter, in order to make the diagnosis as early as possible. Recent evidence shows that early and intensive behavioral and educational intervention can make a significant positive impact on long-term ASD outcomes (McEachin, 1993; Dawson and Osterling, 1997; Greenspan, 1997; Rogers, 1996; Smith, 1997 and 1998). Drs. Johnson, Yeargin-Allsopp and Ziring are members of the AAP Committee on Children With Disabilities. Dr. Yeargin-Allsopp is CDC liaison to the committee and Dr. Ziring is committee chair.

©1999, Reproduced by permission of AAP News
From AAP News, December 1999, p. 25

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