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How do symptoms of autism vary between age groups?

The first signs of autism spectrum disorder typically present in early childhood—often in a child’s first year—and the condition will continue to affect them throughout the course of their lives. While ASD is described as a spectrum specifically because of the variety of ways it can present among individuals, there are some consistent trends among different age groups of people with autism spectrum disorder. Here are some of the most notable ways symptoms of autism vary between age groups.

Autism symptoms in infants

The first two years of a child’s life are the time during which symptoms of autism spectrum disorder are most likely to first present. Here are some common signs to look out for, by age:

By six months: Limited expressions of joy, like big smiles and other engaging behaviors with caregivers and limited or no eye contact

By nine months: Little or no back-and-forth sharing of sounds and limited smiles and other facial expressions

By 12 months: Little or no attempts at verbalization (babbling, intentional noises), limited gestures such as pointing, showing, reaching or waving, and lack of response to name

By 16 months: Very few, or in some cases no words

Autism symptoms in toddlers

In toddlers, symptoms of autism spectrum disorder include:

  • Regression of previously mastered skills—particularly language, communication, and social skills.

  • Loss of previously acquired words

  • Lack of eye contact

  • Lack of response to their name or the sound of familiar voices

  • Aversion to cuddling and physical affection

  • Failure to imitate the movements and facial expressions of caregivers

  • Lack of interest in playing with others

  • Failure to notice when others are hurt or experience discomfort

  • Echolalia—the meaningless repetition of words overheard.

  • Use of other’s body as a tool

  • No use or understanding of gestures

  • Limited range of facial expression

  • Lack of emotional expression

  • Lack of interest in age appropriate play with toys

Autism symptoms in young children

  • Poor social interaction

  • Lack of interest in other children

  • Lack of seeking to share own enjoyment

  • Failure to develop peer relations

  • Failure to join in activities of others

  • Failure to direct adult’s attention to own activity

  • Failure to seek or offer comfort

  • Dislike of social touch

  • Lack of social responsiveness

  • Tendency to ignore people

  • Lack of social play

  • Tendency to “be in their own world”

  • Preference to be alone

  • Indifference to others

  • Failure to differentiate between people

Autism symptoms in older children

By later in childhood and into their early teens, people with autism spectrum disorders may exhibit the following symptoms and behaviors:

  • Trouble taking turns in conversations—either in the form of dominating conversations or preferring only to listen and not speak

  • Obsessive talk a lot about a particular topic

  • Unusual speech pattern or tone

  • Difficulty following instructions with more than one or two steps

  • Trouble reading nonverbal cues, like body language or tone of voice

  • Inappropriate use of eye contact

  • Limited use of gestures and facial expressions

  • Difficulty making or maintaining friendships

  • Development of rigid rules that they require others to follow

  • Difficulty connecting with peers (oftentimes, older children and teens with autism will gravitate toward younger children or adults, rather that people their own age)

  • Poor understanding of personal space and boundaries

  • Unusual interests or obsessions

  • Development of compulsive behaviors

  • Difficulty adapting to changes

  • Sensitivity to sensory experiences

  • Struggles with anxiety and depression

Autism symptoms in teens

While they may develop at any point, these common symptoms of autism spectrum disorder are often particularly pronounced or problematic during the teenage years:

  • Hyperactivity

  • Impulsivity

  • Short attention span

  • Aggression

  • Self injury

  • Meltdowns

  • Unusual eating and sleeping habits

  • Unusual mood or emotional reactions

  • Have unusual sleeping habits

There is some evidence to suggest that symptoms of autism spectrum disorder may improve for some people during their teens. One study, which followed about 300 children from age 2 to 21, found that about ten percent of children improve dramatically by their mid-teens.

The same study found that another 80 percent of the children who were tracked had symptoms that stayed very consistent over time—suggesting that, for most people with ASD, the teenage years will be a turning point in the condition, during which time symptoms are likely to stabilize considerably or even improve.

Autism symptoms in adults

Autism spectrum disorder continues to affect people into adulthood. Some common symptoms experienced by adults with autism spectrum disorder include:

  • Difficulty understanding what others are thinking or feeling

  • Anxiety in and about social situations

  • Difficulty forming friendships

  • A preference to spend time alone, rather than with others

  • Unintentionally appearing blunt, rude or not interested in others

  • Difficulty expressing feelings and emotions

  • Tendency to take things literally and not understand sarcasm and jokes

  • Anxiety when routines are disrupted


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