Children with autism have normal-size heads at birth but develop accelerated head growth between six and nine months of age, a period that precedes the onset of many behaviors that enable physicians to diagnose the developmental disorder, according to new research from the University of Washington’s Autism Center.

The study also indicates that this aberrant growth is present in children who have the early onset form of autism as well as those later diagnosed with the regression type of the disorder, according to Sara Webb, who led the research.

“We know there are a number of risk factors for autism, and if we can pinpoint them we have better ways of identifying children at risk so we can get them into prevention or monitoring,” said Webb, a UW research assistant professor of psychiatry and behavioral sciences.

“This abnormal or accelerated rate of head circumference growth is a biological marker for autism. It occurs before the onset of behavioral symptoms at 12 months of age such as a child’s failure to respond to their name, a preoccupation with certain objects, not pointing to things, a lack of interest in other people and the absence of babbling.

“By itself, head growth is not an indicator of autism,” she said, “because kids are going to be getting bigger and development is so variable. However, if you notice it and some of these other symptoms, it is a red flag to seek evaluation.

She said is it important understand that the data used in this study were based on three measurements made during the first three years of life, not from single point in time. To do this, the researchers obtained the medical records of 28 boys who had been diagnosed with autism spectrum disorder between the ages of 3 and 4 at the UW Autism Center and eight boys with developmental delay. All of the boys were participating in a larger longitudinal study.

Infant head measurements are typically done on a regular basis by pediatricians through the first 18 months of life, but are not reliably done after that. Head circumference is calculated from the brow, or ridge above the eyes, around to the bony bump on the back of the skull and back around to the brow. Three measurements, including at birth, were required to chart the growth of each child and compare it with the range of normal development.

Webb said in most cases parents would have a difficult time detecting abnormal growth because there is a range of normal head sizes. Approximately 20 percent of children with autism have abnormally large head sizes, or what is called macrocephaly.

“Some of the children in our study started with a very small head size and later their growth accelerated. What we are looking for is disproportionate growth in children compared to the rest of their body. In this study nearly 60 percent of the autistic children had accelerated growth but only six of the children met the criteria for macrocephaly.”

Webb said she sees this information being used by pediatricians to screen children and refer them earlier rather than later for evaluation and intervention before other symptoms develop. The UW researchers plan to further explore the implications of abnormal head size as part of a larger autism prevention study of 200 infants at high risk for the disorder that has just started. These youngsters have older siblings already diagnosed with autism and have a one in five chance of developing the disorder, which has a strong genetic component. The typical risk for autism is now believed to be one in 150.

Earlier research at the UW Autism Center by its founding director Geraldine Dawson showed that accelerated head growth in children with autism slows down in the second year of life and this deceleration coincides with a with a period of worsening symptoms of autism.
Source: University of Washington

What is Autism?

Autism is a complex developmental disability that typically appears during the first three years of life and is the result of a neurological disorder that affects the normal functioning of the brain, impacting development in the areas of social interaction and communication skills.

What Causes Autism

Research suggests that autism is a genetic condition. It is believed that several genes are involved in the development of autism. Research studies in autism have found a variety of abnormalities in the brain structure and chemicals in the brain, however, there have been no consistent findings. In rare cases, autism is strongly associated with agents that cause birth defects. One theory is the possibility that autistic disorder is a behavioral syndrome that includes several distinct conditions. However, parenting behaviors are not the cause or a contributing factor to the cause or causes of autism. It remains unclear, but a psychological one has been ruled out. Other proposed causes, such as childhood vaccines, are controversial and the vaccine hypotheses lack convincing scientific evidence.

Autism Symptoms

Autism is a spectrum disorder and it affects each individual differently and at varying degrees.With that being said, the following are the most common symptoms of autism: 

• Delayed language skills (or does not develop language skills)

• Avoids making eye contact with others, including parents

• Does not socially interact well with others, including parents.

• Inability to express needs verbally

• Preoccupied, usually with lights, moving objects, or parts of objects

• Does not like noise

• Insensitivity to pain

• Shows a lack of interest in, or rejection of physical contact. Parents describe autistic infants as "unaffectionate."

• Not comforted by physical contact

• Fails to develop friends or interact with other children

• Does not communicate well with others

• Once language is developed, does not use language to communicate with others

• Has rituals

• Has echolalia (repeats words or phrases repeatedly, like an echo)

• Demonstrates repetitive behaviors

• Has repetitive motor movements (such as rocking and hand or finger flapping)

• Requires routines

• Unmotivated tantrums

• Atypical eating behavior (selectivity is the most common problem, although eating rituals and food refusal also occur)

• Stomach ailments. Although some children with autism also have gastrointestinal (GI) symptoms, there is a lack of published rigorous data to support the theory that autistic children have more or different GI symptoms than usual

• Sleep problems. Known to be more common in children with developmental disabilities, and there is some evidence that children with ASD are more likely to have even more sleep problems than those with other developmental disabilities. Children with ADD may experience problems including difficulty in falling asleep, frequent nocturnal awakenings, and early morning awakenings. Studies have estimated that about two-thirds of children with ASD had a history of sleep problems.

What Parents Should Look Out For

About 50% of  parents of children with ASD notice their child's unusual behaviors by age 18 months, and about four-fifths notice by age 24 months. As postponing treatment may affect long-term outcome, any of the following signs is reason to have a child evaluated by a specialist without delay:

• No eye contact at 3 to 4 month

• No babbling by 12 months.

• No gesturing (pointing, waving goodbye, etc.) by 12 months.

• No single words by 16 months.

• No two-word spontaneous phrases (not including echolalia) by 24 months.

• Any loss of any language or social skills, at any age.

Early diagnosis is crucial. By learning the signs, a child can begin benefiting from one of the many specialized intervention programs, which will help with the socialization skills.