Here are some signs of autism for different age groups:

Infants

No big smiles or other warm, joyful expressions by 6 months or thereafter
No back-and-forth sharing of sounds, smiles, or other facial expressions by 9 months or thereafter
No babbling by 12 months
No back-and-forth gestures such as pointing, showing, reaching, or waving by 12 months
No words by 16 months
No meaningful, two-word phrases (not including imitating or repeating) by 24 months

Toddlers

Doesn’t respond to name
Doesn’t point at objects or things of interest
Doesn’t play “pretend” games
Avoids eye contact
Wants to be alone
Has trouble understanding other people’s feelings or talking about their own feelings

Preschoolers

Has trouble with social interactions
Talks in a flat, robot-like, or sing-song voice about a narrow range of favorite topics
Shows an intense obsession with one or two specific topics
Has a hard time understanding feelings or talking about them
Doesn’t play “pretend” games (for example, doesn’t pretend to “feed” a doll)
Has trouble adapting when a routine changes

Children

Has trouble making friends and often seems uninterested in other people
Avoids eye contact and prefers to play alone
Has trouble understanding other people’s feelings or talking about their own feelings
Has delayed speech and language skills
Repeats words or phrases over and over (echolalia)
Gives unrelated answers to questions

Adolescents

Has trouble making friends and often seems uninterested in other people
Avoids eye contact and prefers to be alone
Has trouble understanding other people’s feelings or talking about their own feelings
Has delayed speech and language skills

Young adults

Difficulty interpreting what others are thinking or feeling
Difficulty interpreting facial expressions, body language, or social cues
Difficulty regulating emotions
Difficulty maintaining friendships
Difficulty finding employment

For discussion of history of DSM-5 Diagnostic criteria for Autism Spectrum Disorders, resources, assesment areas involved in comprehensive pediatric neuropsychological evaluation, and evidence-based treatment of ASD visit our CPANCF.COM Autism Spectrum Disorder Webpage