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Is 2 years old too early to diagnose autism?

Autism spectrum disorder (ASD) refers to a range of conditions characterized by challenges with social skills, repetitive behaviors, speech and nonverbal communication. According to the Centers for Disease Control and Prevention (CDC), about 1 in 44 children has been identified with ASD.

ASD can be reliably diagnosed as early as age 2. But many children are not diagnosed until they are much older. The average age of ASD diagnosis is around 4 years old.

There are benefits to diagnosing ASD early. Early intervention services can greatly improve outcomes. But some experts warn against labeling a toddler too soon. There are also concerns about over-diagnosis of ASD.

Why diagnose autism at age 2?

There are several reasons why diagnosing autism at 24 months is recommended:

  • Autism symptoms typically emerge between 12 and 24 months. During this period, parents may notice delays or differences in communication, social interactions and play skills.
  • Autism can be reliably diagnosed as early as age 2 by an experienced professional. Screening tools and diagnostic methods have improved greatly in recent years.
  • Early intervention has been shown to improve outcomes for children with ASD. Intensive therapies started by age 2 or 3 can help kids acquire speech, social and cognitive skills.
  • The earlier autism treatment begins, the better the results tend to be. Research shows early intervention leads to significant improvements in communication, cognitive ability and daily living skills.
  • Early diagnosis allows parents to get answers to their concerns and start accessing services like speech therapy, occupational therapy and special education preschool.
  • Diagnosing autism at age 2 provides more time for intervention before a child enters school. This extra time can help maximize their readiness and abilities.

For these reasons, age 2 is considered the ideal time to confirm an autism diagnosis. Leading experts, including the CDC and American Academy of Pediatrics, recommend all children be screened for ASD at their 18-month and 24-month well-child visits.

What are the benefits of an early ASD diagnosis?

There are many potential benefits of diagnosing autism at 24 months rather than waiting until a child is older:

  • Earlier access to services – Getting an ASD diagnosis opens the door to early intervention services like speech therapy, occupational therapy and Applied Behavior Analysis. The sooner this starts, the more progress a child is likely to make.
  • Tailored treatment plans – Diagnosis at 2 allows providers to assess the child’s unique profile of strengths and challenges. Therapy can then be individually tailored to target their needs and facilitate growth.
  • Learning critical skills – Starting intensive autism therapy by the age of 2-3 enables children to acquire foundational language, social and cognitive skills when their brains are rapidly developing.
  • Preparing for school – Diagnosis at 2 gives kids an extra year or two of treatment time before starting school. This head start helps maximize their readiness and abilities to participate in a classroom setting.
  • Reduced problem behaviors – Research shows that early intensive behavioral intervention can reduce problematic behaviors like tantrums, aggression and self-injury.
  • Improved outcomes – Studies consistently show that earlier autism diagnosis and treatment leads to better outcomes. Early intervention has an especially dramatic impact on language skills.
  • Peace of mind for parents – An earlier diagnosis provides answers and allows parents to connect with supports. It reduces uncertainty and the stress of not knowing the cause of their child’s issues.

Early, individualized treatment tailored to the child’s challenges provides the best opportunity to help kids with ASD reach their full potential.

What are the drawbacks of an early diagnosis?

While there are advantages to diagnosing autism at 24 months, some experts have concerns about labeling a child at such a young age:

  • ASD is difficult to diagnose very early – Autism symptoms emerge and evolve gradually. Some clinicians argue diagnosis is unreliable before age 3 when symptoms become more clear-cut.
  • Risk of misdiagnosis – Toddlers’ symptoms can fluctuate, so behaviors might not persist. There are concerns about high false positive rates in very young kids.
  • The stigma of a label – Being identified as autistic so early in life could potentially have negative social or psychological impacts on a child.
  • Self-fulfilling prophecy – Early labeling may inadvertently reinforce the autism diagnosis, as both parents and clinicians interpret behaviors through that lens.
  • Resources could be misallocated – Intervention resources are limited. If children are misdiagnosed, it restricts access for those who truly have ASD.
  • ASD has no medical cure – While therapy helps, some believe resources would be better spent on biomedical research to address root causes.
  • Risk of over-diagnosis – Rates of ASD diagnosis have increased substantially. Some believe this reflects an epidemic. Others argue ASD is now being over-diagnosed, especially in high-risk populations.

These are valid concerns. However, they need to be weighed carefully against the proven benefits of early autism diagnosis and intervention in appropriately selected children.

Is diagnosing autism at 2 years old reliable?

There was a time when autism was thought too difficult and unreliable to diagnose before age 3-4 years. But diagnostic capabilities have advanced considerably in recent decades.

Here are some key points about reliably diagnosing ASD at 24 months:

  • From age 2, experienced clinicians can accurately distinguish autism behaviors from normal development or language delays in most cases.
  • Standard diagnostic tools like the ADOS-2 and ADI-R have been adapted and validated for use in children under 3 years old.
  • Autism screening tests like the M-CHAT have been developed and refined specifically for toddlers 16-30 months old.
  • Symptoms that emerge by age 2 are very likely to persist over time, rather than passing delays that often resolve.
  • Diagnostic stability from age 2 through at least age 9 is around 90% in most studies when strict diagnostic methods are used.
  • Clinicians look for marked differences and delays across multiple developmental domains – not just transitory issues – when diagnosing ASD at 24 months.
  • Diagnosis is based on the expert judgment of experienced autism clinicians using standardized tools, observation and parent interviews – not just a checklist.

In summary, autism diagnosis at 24 months is supported by multiple robust scientific studies. When performed rigorously by a qualified professional, it is considered extremely reliable.

What are the autism screening and diagnosis tools for toddlers?

Specialized tools have been developed to help identify and diagnose ASD in very young children. Commonly used autism screening and diagnostic methods include:

Screening Tests

  • M-CHAT(-R) – The Modified Checklist for Autism in Toddlers is a 2-stage parent questionnaire designed to screen for ASD in children 16-30 months old.
  • STAT – The Screening Tool for Autism in Toddlers & Young Children uses interactive activities to screen for ASD at 24 months.
  • ESAT – The Early Screening of Autistic Traits questionnaire screens children 14-15 months old.
  • CSBS DP Infant-Toddler Checklist – This parent checklist screens communication and social development at 12-24 months.

Diagnostic Assessments

  • ADOS-2 Toddler Module – The Autism Diagnostic Observation Schedule is the gold standard observational assessment tool. The toddler module is for kids 12-30 months old.
  • ADI-R – The Autism Diagnostic Interview-Revised is a structured parent interview for diagnosing ASD in children and adults.
  • CARS2-ST – The Childhood Autism Rating Scale 2nd Edition-Standard Version uses clinician observation and ratings for diagnosis.
  • STAT – The Screening Tool for Autism in Toddlers & Young Children has a diagnostic component for clinicians.

Using these evidence-based tools, autism can be accurately identified and diagnosed in most toddlers by an experienced professional.

What is the process for diagnosing autism at age 2?

The process for diagnosing ASD around age 2 years typically involves:

  1. Developmental screening – The child is screened for ASD and other developmental delays at their 18-month and 24-month well-child visits using a tool like the M-CHAT questionnaire.
  2. Evaluation referral – If the screening indicates concerns, the child is referred for a comprehensive ASD evaluation by a specialist such as a developmental pediatrician, child psychologist or neuropsychologist.
  3. Diagnostic assessment – The specialist conducts an extensive assessment which may include clinical observation, parental interviews, developmental testing, hearing and vision tests, and use of tools like the ADOS-2 Toddler Module.
  4. Reviewing results – The clinician reviews all available information to determine if the child meets DSM-5 diagnostic criteria for ASD.
  5. Receiving diagnosis – The family returns to discuss the diagnosis with the clinician and learn about next steps such as intervention services.

This in-depth process allows the specialist to accurately determine if a toddler’s developmental differences truly represent autism versus normal variation or another condition.

What percentage of 2 year old ASD diagnoses persist?

An important question is whether an autism diagnosis made around 24 months “sticks” as the child grows up. What percentage of toddlers diagnosed with ASD retain that diagnosis over time?

Research indicates autism diagnoses at age 2 are very stable through at least the elementary school years when best practices are used:

  • Studies show diagnoses made with gold standard tools like the ADOS-2, ADI-R and DSM criteria have around 90% diagnostic stability from age 2 to age 9 years old.
  • One 10-year study found initial ASD diagnoses made at 20-35 months were confirmed in 87% of cases at 10 years old.
  • Diagnoses by experienced clinicians show greater stability. Stability is lower when tools are used inconsistently or clinicians have inadequate autism training.
  • Younger age at diagnosis is associated with greater diagnostic stability. Diagnoses at 18 months are slightly less stable than those made after 24 months.

While some children may move off the autism spectrum as they mature, research indicates the overwhelming majority of toddlers diagnosed with ASD retain that diagnosis throughout childhood.

What are the statistics on autism diagnosis rates?

Autism diagnosis rates have increased substantially over the past several decades in the United States and other developed countries. Some key autism diagnosis statistics include:

  • In 2000, about 1 in 150 children were identified with ASD.
  • By 2008, this had risen to around 1 in 88 American children.
  • In 2012, ASD prevalence reached 1 in 68 kids.
  • By 2016, 1 in 54 children were diagnosed with ASD.
  • The latest CDC estimate from 2020 is 1 in 44 children identified with autism.

ASD diagnosis rates are about 4 times higher in boys than girls. Rates also vary substantially by state.

The increase in autism diagnoses has mainly been driven by greater awareness, screening, diagnostic substitution and inclusion of milder cases. However, it is unclear how much reflects a true increase in ASD prevalence.

Are autism rates still increasing?

Autism diagnosis rates increased sharply from the 1960s through the early 2000s. However, since around 2010, rates have flattened out in many areas:

  • A California study found autism rates leveled off after 2002. Rates plateaued at around 11 per 1,000 children.
  • Utah data showed the rising ASD trend reversed after 2006. Rates stabilized at 6-7 per 1,000 kids.
  • Studies from Denmark and Sweden found ASD rates stopped going up by the late 1990s. Sweden’s rates have been flat since 2001.
  • A CDC report found autism prevalence plateaued among 8 year olds from 2010-2014 after rising continually in prior years.
  • Reasons for the flattening trend may include saturation of diagnosis, changes in risk factors and the effects of broader ASD criteria in the DSM-5.

While the pace has slowed, autism diagnosis rates have not declined. The latest CDC estimate that 1 in 44 children have ASD is substantially higher than rates in the 1990s. But multiple studies suggest the meteoric rise observed for many years has leveled off in recent times.


In summary, autism spectrum disorder can be reliably identified and diagnosed as early as age 2 years when assessment best practices are followed. There is compelling evidence that early ASD diagnosis leads to improved outcomes due to earlier intensive intervention during critical developmental windows.

However, diagnosing any toddler is complex. There are differing perspectives around labeling children with life-long diagnoses at very young ages. Clinicians must be highly trained and experienced to accurately identify ASD at 24 months and differentiate it from normal development.

While recognizing valid concerns, the bulk of current research indicates age 2 is an appropriate developmental stage at which to diagnose autism in most cases. But diagnosis must be performed rigorously using standardized tools, expert clinical judgment and a comprehensive evaluation process.