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How is Autism Diagnosed?



Parents most often recognize their child is developing differently long before their child receives a formal diagnosis of autism spectrum disorder (ASD). Research has shown a reliable diagnosis can be made by age 2,1 and possibly even younger than that. However, the average age for diagnosis of classic autism is 4 years old, while children with Asperger’s syndrome are diagnosed just after 6 years of age on average.2 Some of the early signs of autism include a lack of babbling by 12 months, failure to respond to their name when called, and repetitive behaviors. Currently, there are no medical tests that can provide a diagnosis of ASD. Instead, parents must enlist the assistance of “experts including psychologists, educators and medical professionals for a diagnosis.”3 Autism shares symptoms with several other conditions that need to be ruled out by the physician conducting the evaluation. The importance of receiving an early and accurate diagnosis cannot be understated. Age-appropriate, effective therapy for ASD “can lead to raised IQ levels and improved language skills and behavior.”4




Milestones like smiling, eye contact, rolling over, first words/steps, and even pointing can provide strong indications about child’s development. Parents who are concerned of their child’s development can take the Modified Checklist for Autism in Toddlers, or M-CHAT, to test the extent to which their child is displaying signs of ASD. The M-CHAT contains a total of 23 simple yes/no questions that will help to assess the need for further evaluation. A parent should seek further evaluation if any three answers suggest a risk for ASD. The Centers for Disease Control and Prevention provides free developmental milestones check sheets ranging from as young as 2 months of age to 5 years of age to help track your child’s developmental progress.5



A child being evaluated for autism may undergo an examination by a “multi-disciplinary team of doctors including a pediatrician, psychologist, speech and language pathologist and occupational therapist.”6 The medical evaluation is made by a physician based on the criteria stated in the Diagnostic and Statistical Manual. The American Psychiatric Association is set to release the fifth version of the Diagnostic and Statistical Manual in May of 2013.7 In addition to a medical evaluation, once the child is school age he/she will undergo an educational determination, or school evaluation, to establish whether or not the child qualifies for special education and related service guaranteed under the Individuals with Disabilities Education Act (IDEA).3



School Evaluations and IEPs


The school evaluation will determine if the child qualifies for special services and/or requires an Individualized Education Program (IEP). According to IDEA,8 the initial school evaluation of an IEP one of two things must take place:


  • A parent must request an evaluation by contacting the director of special education or the school’s principal.
  • Or, the school can determine that the child should undergo an evaluation. Before the school can conduct this procedure they need written consent from a parent

Under IDEA, the persons conducting the evaluation must assess “all areas [related] to the suspected disability.”8 This includes, but is not limited to, health, vision, hearing, communication abilities, motor skills, and social and/or emotional status.9 Parents may opt to provide consent for the school to conduct only some of the evaluations. For example, the parents may decide to have their child’s psychological evaluation performed by their personal psychologist while providing consent for the school to conduct the necessary school evaluations. Under IDEA, children with disabilities “have available to them a free appropriate public education that emphasizes special education and related services to meet their unique needs and prepare them for further education, employment, and independent living.”10 IEPs are designed specifically to meet your child’s unique needs. Free and appropriate education (FAPE) and related services must be provided for any child with a qualifying disability by the school district at no cost to the parents.11



Medical Assessment


The medical professionals who may have experience with autism and other neuro-developmental disorders are developmental pediatricians, neurologists, and child and adolescent psychiatrists or psychologists.12 Some of these professionals in your area may not have experience diagnosing and evaluating children with autism spectrum disorder.


Parents and caregivers should seek out knowledgeable professionals in their area from:


Receiving an accurate diagnosis at the earliest age possible is important for a child. Parents should immediately seek out the help of qualified, knowledgeable professionals if they feel their child is not typically developing.



Every individual on the autism spectrum experiences the disorder in a different way. An initial medical assessment of a person suspected of having autism typically includes:


  • A medical history of the mother’s pregnancy
  • Review of developmental milestones (home videos/baby book records can assist in this process)
  • Eating and sleeping habits
  • Coordination
  • Stomach and bowl functioning
  • Allergies
  • Medical illnesses, including ear infections, seizures
  • Family history of development disorders
  • Family history of genetic and metabolic disorders
  • A thorough physical exam
  • Routine lab tests

The American Academy of Pediatrics recommends that your child undergo a pediatric screening for autism at 18 and 24 months of age.13 Parents concerned with their child’s development are encouraged to contact their state’s early childhood system to request a free evaluation that will determine if their child meets the qualifications for intervention services. Parents and caregivers DO NOT need to wait for a doctor’s referral or medical diagnosis to receive early intervention services that can greatly improve a child’s development.



What Tools are Used to Diagnose Autism?


Traditionally, autism is diagnosed by either implementing the Autism Diagnostic Interview-Revised, which is a 93-question questionnaire, or the Autism Diagnostic Observation Schedule (ADOS), which is administered by a clinician observing 29 specific behaviors. Each of these clinical assessments can take up to three hours to be completed and look at the criteria set by the DSM-IV. The Autism Diagnostic Interview-Revised was developed by Michael Rutter, Catherine Lord, and Anne Le Couteur and published by Western Psychological Services in 2003.14 The test can be effective at providing a diagnosis for children 2 years of age and above. The Autism Diagnostic Observation Schedule is broken down into 4 30-minute modules that assess the child’s social interaction, communication, play, and imaginative use of materials.15 These methods have been the gold standard for diagnosing autism since they were developed.


Unfortunately, there is not an abundance of skilled clinicians available to conduct these evaluations and to provide an accurate diagnosis. Furthermore, clinicians “also tend to be heavily concentrated in large urban centers, and especially on the two coasts, leaving families in rural areas and in the middle of the country with longer delays and costs in receiving diagnosis.”16 These restrictions can cost children valuable time that could be spent undergoing early intervention strategies that have proven more effective when received at a young age.17 Fortunately, there are researchers working to develop methods for autism diagnosis that are more efficient, effective, and more easily accessible.

A newly developed diagnostic test for autism, created by Harvard Medical Professor Dennis Wall, has been shown to detect autism with nearly 100 percent accuracy, and “could reduce the time for autism diagnosis by nearly 95 percent, from hours to minutes, and could be easily integrated into routine child screening practices to enable a dramatic increase in reach to the population at risk.”18 Wall “turned to ‘machine-learning’ software—a type of artificial intelligence technology that can discern patterns in data in a way that allows it to mimic the decisions of a trained expert.”16 Wall’s test consists of 7 survey questions accompanied with a home-video of your child, all of which can be conducted and evaluated online, accurately making a diagnosis in a matter of minutes instead of hours.19 To arrive at the magic number of 7, Wall and his team “studied the results of the ADI-R from the Autism Genetic Research Exchange for more than 800 individuals diagnosed with autism to find redundancies across the exam. They found that only seven questions were sufficient to diagnose autism with nearly 100 percent accuracy, equivalent to the full 93-question exam.”18 The test was also verified using information on nearly 2,000 children from the Simons Simplex Collection (SSC) and 424 individuals from the Autism Consortium.16 This trial yielded similar results as “[t]he software is in near-perfect agreement with clinicians on positive diagnoses.”16 Although these results are promising, the team must conduct more testing before parents are able to receive an accurate online diagnosis for their child. The hope is that the analysis of the survey and accompanying home-video will not only cut down on the time it normally takes to wait for an appointment from a qualified physician or psychologist, but also lower the average age of autism diagnosis, which is currently 4 years of age.20 If you are a parent or caregiver of an individual with autism and would like to participate in testing the accuracy of this evaluation, please visit the Autworks Page.



Another diagnostic tool for autism that has recently been developed by researchers utilizes genetics to determine if a sibling of an individual with autism is at a greater risk for developing ASD. The test is not an autism diagnosis, but instead “is designed to allow for the early estimate of a sibling’s risk of autism.”21 The ARISk Autism Risk Assessment test is based on studies that “have shown that the presence of a combination of autism-associated SNPs can predict with a high degree of certainty whether that child will develop ASD.”22 Single nucleotide polymorphisms or SNPs are genetic variations in a DNA sequence that occur when a single nucleotide in a genome is altered.22 The test can be given to infants as young as 6 months of age. Unfortunately, this test is only applicable to siblings of individuals already diagnosed as being on the autism spectrum. However, IntegraGen, the company who created the ARISk test, is currently developing a genetic screen for autism appropriate for all children, regardless of family history. 23



Co-Occurring Conditions


Autism spectrum disorders can have numerous effects on the body and brain. The complexity of the disorder is apparent by observing the co-occurring conditions that are present in some individuals with ASD. Click here for a detailed list of the co-occurring conditions of autism.


Differential Diagnosis:


The characteristics of autism are also present in a number of other conditions. Professionals must use caution and conduct thorough evaluations as to rule out the possibility of these related syndromes/disorders. Click here for a list conditions that are similar to autism and tend to be more prevalent in individuals on the autism spectrum.


Pervasive Developmental Disorders (PDD)
PDD-NOS is short for Pervasive Developmental Disorder-Not Otherwise Specified. The terms “pervasive developmental disorder” and “autism spectrum disorders” are used interchangeably by psychologists and psychiatrists.24 Individuals diagnosed with PDD-NOS display some behaviors that are present in “classic autism”, but do not meet the full criteria necessary for full diagnosis. Receiving the correct diagnosis is important for tailoring proper interventions to an individual’s needs. Consistent with the procedures following an autism diagnosis, children with PDD-NOS should undergo a developmental evaluation, obtain an IEP, and undergo intervention early as possible.

Adult Diagnosis


Some individuals are not diagnosed with a form of autism until they reach adulthood. Asperger’s syndrome, a neurological condition marked by difficulties in displaying and understanding social norms, has been diagnosed in a number of adults without them being aware they ever had the condition. The main difference between Asperger syndrome and “classic autism” is that there is no cognitive or language delay.25 This, coupled with the fact that Asperger’s was not included as a separate disorder from autism until the publication of the DSM-IV in 1994,26 has led to many individuals being diagnosed with Asperger’s syndrome as adults.



Any individual that suspects they have Asperger’s syndrome should seek out an official diagnosis. Adults also require an official diagnosis to qualify for Supplemental Security Income, Social Security Disability Insurance, or to make reasonable accommodation requests from your employer under the Americans with Disabilities Act (ADA).27 Clearly, the earlier the diagnosis, the more time the individual has to seek out intervention strategies to quell some of the challenges presented by Asperger’s syndrome. However, no individual is too old to receive an official diagnosis that can allow an individual to customize their workplace/home environment to accommodate their strengths and challenges. Individuals capable of providing an adult autism diagnosis include clinical psychologists, neurologists, and psychiatrists.28



References