Early autism signs show up in how a baby connects: not responding to their name by 9 months, or not pointing to show you things by 18 months. ADHD is hard to diagnose before age 4. Spot something? Call your pediatrician, and in Massachusetts ask for a free evaluation from Early Intervention (under 3) or your school district (3 and up). You don’t need a diagnosis first.

By our editors · Facts checked October 7, 2026. This guide is general information, not medical advice.

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The short version

  • Screening is a quick check. Diagnosis is a full evaluation by specialists. A positive screen is not a diagnosis, and a negative one doesn’t rule autism out.
  • Pediatricians should screen for autism at the 18- and 24-month checkups.
  • AAP guidelines for diagnosing ADHD start at age 4.
  • You don’t need a diagnosis to start Early Intervention or to ask your district for an evaluation.
  • Vaccines don’t cause autism. Bad parenting doesn’t cause ADHD.
A hand builds a small house from colorful wooden blocks on a table
Photo: Michał Bożek / Unsplash

Early signs of autism, age by age

Autism affects how a child communicates, interacts and behaves. The CDC lists social and communication signs that can show up at different ages. An autistic child may not show all of them, and some kids who aren’t autistic show a few.

AgeA possible sign (CDC)
9 monthsDoesn’t respond to their name; doesn’t show expressions like happy, sad, angry or surprised
12 monthsDoesn’t play back-and-forth games like pat-a-cake; uses few or no gestures, like waving
15 monthsDoesn’t share interests, like bringing you a toy to show you
18 monthsDoesn’t point to show you something interesting
2 yearsDoesn’t notice when others are hurt or upset
3 yearsDoesn’t notice other children or join them in play
4 yearsDoesn’t pretend to be someone else, like a teacher or superhero
5 yearsDoesn’t sing, dance or act for you

The CDC also describes repetitive behaviors, such as:

  • Lining up toys and getting upset when the order changes
  • Repeating words or phrases (echolalia)
  • Focusing on parts of toys, like wheels
  • Getting very upset by small changes in routine
  • Hand flapping, rocking or spinning
  • Unusual reactions to sounds, smells, tastes, textures or sights

Here’s the catch: most autistic kids sit, crawl and walk on time, so the AAP warns social and communication delays can be missed. And if your child loses skills they once had, the CDC says talk with the doctor and act early. Talking late is its own topic; see our guide to speech milestones and delays.

Early signs of ADHD in young kids

Almost every preschooler is wiggly, impulsive and distractible sometimes. The AAP says the concern with ADHD is behavior that sticks around as other kids outgrow it and gets in the way of daily life.

Signs the CDC describes include nonstop running and climbing, trouble waiting or taking turns, interrupting, grabbing, fidgeting, and trouble following directions or finishing tasks. Not sure if it’s ADHD or a classic toddler meltdown? Our tantrum guide covers what’s typical.

AAP diagnosis guidelines apply from age 4. A doctor looks for symptoms lasting more than six months, showing up in at least two settings, like home and preschool, and causing real problems. Sleep problems, anxiety, learning disabilities, and hearing or vision problems can look like ADHD, so a medical exam is part of the process.

Screening vs. diagnosis: what’s the difference?

StepWhat it isWho does it
MonitoringWatching milestones over time. The free CDC Milestone Tracker app can help.Parents, caregivers, teachers, doctors
ScreeningA short questionnaire that shows whether a child needs a closer lookPediatrician or other provider
Diagnostic evaluationAn in-depth assessment that can lead to a diagnosisDevelopmental pediatricians, child psychologists, speech-language pathologists, occupational therapists

That breakdown comes from the CDC, which also notes the AAP recommends developmental screening at 9, 18 and 30 months and autism screening at 18 and 24 months. By age 2, experts consider a diagnosis from an experienced professional reliable.

The most common autism screener is the M-CHAT-R/F, a parent questionnaire for toddlers 16 to 30 months. Its authors say many kids who screen positive aren’t diagnosed with autism but often have other delays, so a positive screen should lead to an evaluation. A parent’s concern is reason enough for a referral, whatever the score.

How to get a free evaluation in Massachusetts

Under 3: Early Intervention

Massachusetts Early Intervention serves kids from birth to 3, and anyone can refer a child to the program for your city or town. The CDC notes no doctor’s referral is needed, and the state says there are no out-of-pocket costs.

Kids don’t need a diagnosis to qualify, and a child diagnosed with autism is eligible on that basis. The state EI directory lists 22 specialty providers offering early intensive behavioral services for autistic kids under 3. If your child qualifies, you and the team write an IFSP within 45 days of the referral, per the state handbook.

Age 3 and up: your school district

Districts provide Early Childhood Special Education for ages 3 to 5 at no cost. Ask for an evaluation in writing and keep a dated copy. Under state rules, the district must send notice seeking your consent within five school days and finish the evaluation within 30 school days after you consent. Eligible kids get an IEP; here’s how an IEP differs from a 504 plan.

What to do while you wait

  • Start EI or the school evaluation now. Services don’t have to wait for a diagnosis.
  • Ask about a hearing test. Hearing and vision checks are part of an ADHD workup.
  • Keep notes and short videos of what you see at home.
  • Fill out a free milestone checklist before the visit, as the AAP suggests.
  • Ask your child’s teacher what they notice. The AAP recommends asking about behavior in several settings.
  • For a preschooler with ADHD-like behavior, ask about parent training in behavior management. The CDC says the AAP recommends it first for kids under 6.
  • Be skeptical of miracle claims online. The AAP warns many are untrue and often profit-driven.

Myths to drop right now

  • Vaccines don’t cause autism. The AAP says decades of large studies show no link, and it has called recent claims added to a CDC autism webpage misleading.
  • Studies don’t show acetaminophen (Tylenol) causes autism, per the AAP. Autism has many influences, much of them genetic.
  • There’s no evidence screen time causes autism, the AAP says. More in our screen time guide.
  • Bad discipline doesn’t cause ADHD, though the AAP notes inconsistent limits can make symptoms worse. And a kid who can game for hours can still have ADHD.

About 1 in 31 U.S. children are identified as autistic by age 8, based on 2022 data, the AAP reports. An evaluation isn’t a verdict on your parenting. It’s how you find out what your child needs.

For children who need extra support

Some kids are more likely to be autistic. The AAP says a sibling of an autistic child is 10 to 20 times more likely than the general population, and autism is more common in kids born preterm and in kids with fragile X or Down syndrome. The CDC says higher-risk kids should get additional screening.

After a diagnosis, the AAP recommends a plan built around your child, because no single service fits every kid. When you look for child care, ask how programs include children with disabilities; our daycare search guide lists the questions. More on our inclusive care hub.

Common questions

Can autism be diagnosed before age 2?

Sometimes. The CDC says autism can sometimes be detected at 18 months or younger, and a diagnosis by an experienced professional is considered reliable by age 2. Many kids are diagnosed much later.

Can a toddler be diagnosed with ADHD?

It’s uncommon. AAP guidelines start at age 4 because young kids change so fast. If a toddler’s behavior worries you, an EI evaluation looks at development as a whole.

My child passed the M-CHAT, but I’m still worried. Now what?

Screening misses some kids. The M-CHAT authors say a parent’s concern warrants a referral regardless of score, and the AAP says get a second opinion if your concerns aren’t taken seriously. You can also call EI or your district directly.

Do I need a diagnosis to get help?

No. EI doesn’t require one, and your district runs its own evaluation to decide eligibility. A medical diagnosis can still matter, for example for insurance coverage of some therapies, so you can pursue both at once.

Looking for bilingual care or pediatric therapy on the North Shore? Our publisher, Treehouse Learning Center, has programs in Lynn.

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