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Autism Across the Lifespan

Autism Across the Lifespan

Autism begins in early childhood and continues through adulthood, but what it looks like — and what helps — changes with age. Here is what to expect at each stage.

Based on NIMH · CDC · AAP / HealthyChildren.org · Organization for Autism Research · WHO · All sources · Checked November 3, 2026

Before 3autism begins before age 3 and can last throughout lifeCDC
47 monthsmedian age of earliest known diagnosis among eight-year-oldsCDC ADDM Network · 2022 data
Age 12a good time to start thinking about the transition to adulthoodAAP · HealthyChildren.org

Autism is lifelong — and it changes

CDC says autism begins before age 3 and can last throughout a person’s life, though characteristics may change over time. WHO describes abilities and needs that vary and can change over a lifetime. The sections below describe what agencies say about each stage; none of it is a timetable for any one person.

Babies and toddlers

CDC notes that some children show characteristics in the first 12 months, while others do not show them until 24 months or later. Some children gain skills until about 18 to 24 months and then stop gaining skills or lose skills they had. Autism can sometimes be detected at 18 months or younger, and a diagnosis by an experienced professional by age 2 can be considered reliable. Families can ask for a screening at any well-child visit and can contact their state early intervention program directly. Screening and early identification.

School-age children

Many children are identified during the school years. In CDC’s 2022 data, the median age of earliest known autism diagnosis among eight-year-olds was 47 months, and only about half had been evaluated by age 36 months. NIMH notes that caregivers and teachers are often the first to notice autism in older children, and that the school’s special education team may do an initial evaluation. At this age, differences may be subtle — understanding tone of voice, humor or sarcasm, or forming friendships.

Teenagers

CDC observes that adolescents and young adults may find it hard to make friends, to communicate with peers and adults, and to understand what behaviors are expected at school or work. The American Academy of Pediatrics suggests starting to think about the transition to adulthood at about age 12, because many changes begin then and continue into adulthood — and because autistic people often prefer predictability, preparation makes the transition smoother. The AAP recommends keeping regular pediatrician visits, building self-advocacy skills such as scheduling appointments and taking part in medical decisions, and planning for daily-living skills. Anxiety and depression are common in autistic youth; co-occurring conditions has more.

Adulthood

The AAP notes that legal responsibilities change at 18, including for health care decisions. CDC says that as individuals leave high school, additional services can help improve health and daily functioning and support social and community engagement. The Organization for Autism Research describes high school, college and the job market as both exciting and challenging for autistic teens and adults, and names employment as one of the biggest societal barriers autistic people face. NIMH notes that studies are under way to identify the most helpful services for autistic transition-age youth and adults.

Identified as an adult

Some people are not identified until adulthood. NIMH explains that diagnosing autism in adults can be harder because some characteristics overlap with anxiety or ADHD; adults can be referred to a neuropsychologist, psychologist or psychiatrist experienced with autism, and the evaluation may include family members’ memories of early development. A correct diagnosis can help people understand past challenges, identify strengths and find the right kind of help. Adult identification and diagnosis.

This website provides general educational information. It does not diagnose autism or replace individualized medical, developmental, psychological, or educational advice. Screening is not diagnosis.

External listings do not imply affiliation, endorsement, or guaranteed services. Eligibility, availability, costs, and insurance coverage may change. Research summaries reflect evidence available at the time of review.