All of us in the field of autism spectrum disorders — parents, doctors, therapists, researchers and activists — agree that early identification is essential for enabling early intervention and investigating underlying causes. Many of the tools, such as the Modified Checklist for Autism in Toddlers (M-CHAT), that doctors use to screen young children for autism are effective for children older than 18 months. However, identifying children at risk for autism within the first year of life will enable them to receive intervention and treatment during crucial early stages of brain development, thereby maximizing their potential.
It is recommended that developmental surveillance take place at each pediatric visit throughout early childhood. Screening for autism and other developmental disabilities should be instituted if concerns are identified during the surveillance assessment. Pediatricians should refer their patients who are at risk for autism to a developmental pediatrician, a pediatric neurologist or a child psychiatrist for further evaluation.
The Link Between Head Circumference and Autism
In younger toddlers and babies, objective, quantitative guidelines may prove to be useful for identifying an increased risk for autism before children begin to show the behavioral indicators of autism. Head circumference may be an important biological marker that would aid early diagnosis of autism within the child’s first year, months before the M-CHAT or other developmental checklists are implemented. Between one and 12 months, babies with autism experience head growth at faster rates than typically developing babies.
As far back as 1943, studies conducted by Kanner found that increased head circumference could indicate attributes consistent with autism spectrum disorders. More recent studies (Elder at al 2008, Dawson et al 2007) have also examined rates of head growth during the first few years of life in order to explore whether toddlers with more rapid head growth are more likely to develop autism.
These studies identified significant acceleration in head circumference growth during the period from six to 12 months of age in those infants who went on to show signs of autism. In addition, between the ages of 12 and 24 months, rates of head growth returned to a rate that mirrored typically developing children. These studies concluded that rates of head circumference growth between 6 and 12 months may be useful in identifying children who are at risk for developing signs of autism.
In a retrospective study by Fukumoto and colleagues (2008), a pattern of significant increase in rate of head circumference growth for children who went on to receive the diagnosis of autism was noted as early as one month of age. The authors concluded that the rate of head circumference growth could be easily monitored using accurate measurements of head circumference by pediatricians and noted that the period between one month and three months should be an area of particular focus.
Pediatricians may be able to use measurements of head circumference during well baby checkups to identify children at increased risk for autism, particularly younger siblings of children with autism. It is recommended that physicians measure babies’ heads at birth, one month, three months, six months, nine months and 12 months. The pediatricians could then closely monitor their patients and refer them for further evaluation, if necessary. This approach would enable pediatricians to identify those of potential risk of autism up to a year earlier than is currently the case, resulting in earlier intervention and possibly more favorable outcomes for children with autism spectrum disorders.
Behavioral Indicators of Autism
While rates of head growth may be used to identify risk for autism in babies, most children with autism are diagnosed after manifesting behavioral signs. Because of their routine evaluations of children younger than age 3, primary care physicians play a vital role in the identification of children at risk for autism spectrum disorders.
The American Academy of Pediatrics recommends that all children be given autism specific screenings at 18, 24 and 36 months of age. These screenings should take place even if the general developmental screening tools did not indicate a risk. A recent study (Pinto-Martin et al, 2008) found that a general developmental screening tool missed the majority of children who were found to have an autism spectrum disorder when screened using the Modified Checklist for Autism in Toddlers (M-CHAT). The study supported the American Academy of Pediatrics’ guidelines that an autism-specific screening tool should be administered during routine developmental surveillance, in addition to an established general developmental screening tool. The study found that if pediatricians were to rely solely on the outcome of the general developmental screening tool, they would miss a significant proportion of children who are at risk of developing autism.
The M-CHAT is a useful tool for pediatricians and parents because it has demonstrated significant sensitivity and specificity, usually in children older than 18 months. The checklist is based on identifying the social and communication delays in children with autism. The items on the questionnaire focus on the child’s joint attention, eye contact, interactions and behaviors.
A growing body of research aims to identify early reliable indicators of autism. One of the most common behaviors separating infants with autism from typically developing infants is an abnormal response to their names being called. The failure to respond to their own name at age 12 months of age may be a reliable marker of autism (Nadiq et al, 2007), especially if the infant also shows reduced eye contact and a lack of interest in other people’s faces.
Testing for name response at 12 months during well-child pediatric visits may be an effective way to screen for autism. If a child does not respond to his or her name being called, pediatricians are encouraged to make a referral for a more comprehensive assessment.
While it is clear that rigorous measuring and tracking of children’s head circumferences and the administering of autism-specific screening tools will identify many children at risk for autism, these strategies take time. Primary care physicians and pediatricians are under more pressure than ever before to see more patients in less time. Crowded waiting rooms present a real-world challenge for doctors who spend an average of 10-15 minutes with their patients. Carving out time for diagnostic screening and surveillance is perhaps the biggest obstacle confronting doctors in the early identification of children with autism spectrum disorders.
The Child Neurology Society has identified the following red flags that would indicate an immediate need for an evaluation. These include:
- No babbling or pointing or other gesture by 12 months of age.
- No single words by 16 months.
- No two word spontaneous phrases by 24 months.
- Loss of language and social skills at any age.
Charles Cartwright, MD is Director of the YAI Autism Center at the YAI/National Institute for People with Disabilities Network. Amerha Rafiq, MD is Pediatrician for Premier HealthCare at the YAI/National Institute for People with Disabilities Network.