Articles and Topics
Understanding Autism Part 1: Recognizing the Possible Symptoms
This is the first in a three-part series on the symptoms of autism, its diagnosis and treatment options.

With increased numbers of children diagnosed with autism over the past two decades, it is crucial that parents, childcare providers, teachers and health professionals understand what autism is, how to recognize the symptoms and how to get prompt evaluation and treatment for children. Although there are still many unanswered questions about autism, there is much that we do know about it.

What is autism?
Autism is now considered part of the Autism Spectrum Disorders (ASDs), including autistic disorder, pervasive developmental disorder not otherwise specified, Asperger Syndrome, Rett’s Disorder and childhood disintegrative disorder. ASDs are developmental conditions that affect children’s social skills, language/communication and behavior. Children with ASD tend to have difficulty interacting with others; absent, delayed or unusual language skills; and unusual or repetitive behaviors. Symptoms of ASD appear before 3 years of age. Each of the ASD conditions has slightly different symptoms, and each child has an individual pattern of behavior. Some have more severe symptoms and others have milder symptoms. For example, children with Asperger Syndrome tend to have better language abilities. ASD is three to four times more common in boys than girls.

What are the signs and symptoms of ASD, and when do they develop?
Many children with ASD appear to develop normally in their first year of life because they may master early motor skills—sitting up, crawling and walking—on time. The characteristic problems with communication and social skills may not be apparent until 1 to 3 years of age. Some parents observe early delays in their child’s development or gradual changes where their child stops progressing. Other parents observe that their child seems to be developing normally and then suddenly loses language and social skills from 12 to 24 months. In retrospect, many parents of children with ASD say they sensed that something was different about their child’s development and behavior, but they weren’t sure what it was.

The following are examples of characteristics that a child with ASD may have.

Social skills:
  • Does not snuggle when picked up.
  • Does not make eye contact.
  • Does not respond to a parent’s smile or other facial expressions.
  • Does not look at objects that parents point to or point to objects for parents to look at.
  • Does not bring objects to show parents.
  • Has difficulty perceiving what others might think or feel by looking at their facial expression.
  • Has difficulty making friends.

  • Does not say single words by 15 to16 months or two-word phrases by 24 months.
  • Loses language skills, usually from 15 to 24 months of age.
  • Does not respond to his name but responds to other sounds, such as a car horn or a dog’s bark.
  • Often does not seem to want to communicate. Does not start or continue a conversation.
  • May speak in a monotone, lack eye contact, use very advanced language or have difficulty with back-and-forth conversation.
  • May have an especially good memory for numbers, songs, TV jingles or a specific topic.

  • Rocks, spins, sways, twirls fingers, flaps hands or injures self.
  • Repeats certain activities over and over. Insists on routines, order and rituals.
  • Plays with parts of toys instead of the whole toy (for example, spinning the wheels of a toy truck).
  • Does not use dolls, stuffed animals or toys in pretend play.
  • May be overly sensitive or insensitive to smells, sounds, lights, textures and touch.
  • Does not cry if in pain or seem to have fear.
  • May look at objects from unusual angles.
  • May have unusual and intense interests, and special skills.

Other symptoms that may be associated with ASD are attention problems, hyperactivity, aggression, mood instability, mental retardation, seizures, tics, sleep problems and chronic constipation or diarrhea.

What causes ASD and how common is it?
It is estimated that four to six out of 1,000 children have ASD. There has been a large increase in the number of children diagnosed with ASD in the past decade, but we don’t yet understand the causes of ASD and the reasons for the increase. In the past, the diagnosis of autism was given only to children with the most severe symptoms, but the current diagnosis of ASD includes many more children with mild symptoms. ASD appears to be genetic or inherited. If a family already has a child with ASD, they have an increased chance of having another child with ASD.

Currently, many studies are being done to determine whether ASD might also be caused by exposure to prenatal or early childhood medications, infections and toxins. There is a hypothesis that children with ASD may have a genetic sensitivity to the harmful effects of toxins. Many studies have investigated a possible connection between autism and the MMR vaccine and thimerosol, the mercury preservative contained in some infant vaccines from 1988 to 2002 (currently, all of the infant vaccines are available in thimerosol-free preparations). No connection was demonstrated between these vaccines and autism for the overall population of children. But since mercury is known to be toxic to the nervous system, the authorities concluded that there may be a connection in a small proportion of susceptible children. For this reason, we need to reduce the exposure of all pregnant women and children to toxins, such as mercury in vaccines and fish, and conduct more research to better understand the causes of autism and how to prevent it.

How is ASD diagnosed?
ASD is diagnosed using parents’ and other caregivers’ reports of the child’s behavior, and comprehensive professional evaluations of the child by a doctor, psychologist or a team of developmental specialists. The earlier a child is diagnosed with ASD and the earlier treatment is begun, the better the outcome for the child’s development. For these reasons, parents and other caregivers should look for possible early signs of autism, stay on schedule for the well-baby medical visits (at 2, 4, 6, 9, 12, 15, 18 and 24 months of age), and be sure to talk with the doctor about your child’s development and behavior at every visit.

For more information on the evaluation and diagnosis of ASD, see my article titled “Understanding Autism, Part 2: Evaluation and Diagnosis.” Also, visit and For more information on the studies of vaccines and autism, visit the Centers for Disease Control at
Karen Sokal-Gutierrez M.D., M.P.H. Pediatrician