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How is ASD diagnosed?

ASD diagnosis is often a two-stage process. The first stage involves general developmental screening during well-child checkups with a pediatrician or an early childhood health care provider. Children who show some developmental problems are referred for additional evaluation. The second stage involves a thorough evaluation by a team of doctors and other health professionals with a wide range of specialities.12 At this stage, a child may be diagnosed as having autism or another developmental disorder.

Children with autism spectrum disorder (ASD) can usually be reliably diagnosed by age 2, though research suggests that some screening tests can be helpful at 18 months or even younger.12,13

Many people—including pediatricians, family doctors, teachers, and parents—may minimize signs of ASD at first, believing that children will "catch up" with their peers. While you may be concerned about labeling your young child with ASD, the earlier the disorder is diagnosed, the sooner specific interventions may begin. Early intervention can reduce or prevent the more severe disabilities associated with ASD. Early intervention may also improve your child's IQ, language, and everyday functional skills, also called adaptive behavior.14

Screening

A well-child checkup should include a developmental screening test, with specific ASD screening at 18 and 24 months as recommended by the American Academy of Pediatrics.14 Screening for ASD is not the same as diagnosing ASD. Screening instruments are used as a first step to tell the doctor whether a child needs more testing. If your child's pediatrician does not routinely screen your child for ASD, ask that it be done.

For parents, your own experiences and concerns about your child's development will be very important in the screening process. Keep your own notes about your child's development and look through family videos, photos, and baby albums to help you remember when you first noticed each behavior and when your child reached certain developmental milestones.

Types of ASD screening instruments

Sometimes the doctor will ask parents questions about the child's symptoms to screen for ASD. Other screening instruments combine information from parents with the doctor's own observations of the child. Examples of screening instruments for toddlers and preschoolers include:

To screen for mild ASD or Asperger syndrome in older children, the doctor may rely on different screening instruments, such as:

Some helpful resources on ASD screening include the Center for Disease Control and Prevention's General Developmental Screening tools and ASD Specific Screening tools on their websiteExternal Link: Please review our disclaimer..

Comprehensive diagnostic evaluation

The second stage of diagnosis must be thorough in order to find whether other conditions may be causing your child's symptoms. For more information, see the section: What are some other conditions that children with ASD may have?

A team that includes a psychologist, a neurologist, a psychiatrist, a speech therapist, or other professionals experienced in diagnosing ASD may do this evaluation. The evaluation may assess the child's cognitive level (thinking skills), language level, and adaptive behavior (age-appropriate skills needed to complete daily activities independently, for example eating, dressing, and toileting).

Because ASD is a complex disorder that sometimes occurs along with other illnesses or learning disorders, the comprehensive evaluation may include brain imaging and gene tests, along with in-depth memory, problem-solving, and language testing.12 Children with any delayed development should also get a hearing test and be screened for lead poisoning as part of the comprehensive evaluation.

Although children can lose their hearing along with developing ASD, common ASD symptoms (such as not turning to face a person calling their name) can also make it seem that children cannot hear when in fact they can. If a child is not responding to speech, especially to his or her name, it's important for the doctor to test whether a child has hearing loss.

The evaluation process is a good time for parents and caregivers to ask questions and get advice from the whole evaluation team. The outcome of the evaluation will help plan for treatment and interventions to help your child. Be sure to ask who you can contact with follow-up questions.

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