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Symptoms of Autism

Autism spectrum disorders (ASDs) are a set of developmental disabilities marked by deficits in social and communication skills. Autism is referred to as a “spectrum disorder” because it varies in severity on a case by case basis. Individuals on the autism spectrum share common difficulties with social interaction, but they may also experience symptoms such as pica, problems sleeping, chronic constipation/diarrhea, sensory integration disorder, allergies/immune system dysfunction, low muscle tone, seizures, and hearing/visual impairments.1

The symptoms of autism manifest in the early stages of an individual’s life and can affect them throughout their life, but many interventions exist to help improve the symptoms associated with ASD. Children on the autism spectrum show signs of the disorder at different stages of childhood. The signs of a developmental disorder can be seen as early as the child’s first birthday, however most individuals do not receive an autism diagnosis until the age of 4.2 Some children develop typically until approximately 18 to 24 months of age and then stop gaining new skills or lose skills they once had.2 Research has demonstrated that as many as 20% to 40% of toddlers that seem to develop normal communication skills can experience regression later in life.3

According to the CDC2, some of the early warning “Red Flags” for autism include:

  • Failure to respond to their name by 12 months of age
  • Not pointing at objects of interest by 14 months of age
  • Not playing “pretend” games (an imaginary tea party/role playing with stuff animals) by 18 months
  • Avoiding eye contact and preferring to be alone
  • Inability to understand other’s feelings or refusal to express their own feelings
  • Delay in the development of speech/language skills
  • Echolalia
  • Providing unrelated answers when asked a question
  • Becoming frustrated by minor changes
  • Obsession with a single interest (puzzles, building blocks)
  • Constant movement: rocking back and forth, flapping their hand repeatedly, spinning in circles
  • Having uncommon responses to the way things sound, smell, taste, look, or feel

Social Skills

Individuals on the autism spectrum share a common weakness in the area of social skills. This weakness doesn’t only reflect in challenges in making friends, but can negatively affect how individuals with autism live life day-to-day. According to the CDC fact sheet on autism,4 some of the social difficulties related to ASDs include:

  • Failure to respond to name by 12 months of age
  • Avoiding eye-contact
  • Not play pretend games (pretend tea-party)
  • Resistance to cuddling and holding
  • Lacks ability to understand what others are feeling
  • Appears to not hear others in the room
  • Preferring to be alone instead of interacting with others
  • Has trouble adapting to changes in routine

While many children around the age of 1 show enthusiasm in learning about many of aspects of the world around them, individuals developing autism may have difficulty learning and interacting with others. This failure to interact with others through proper sharing, turn taking, and finding common interests can lead to other children not wanted to interact with the child, leading to isolation.2 Individuals on the autism spectrum may have a difficult time expressing their feelings and emotions. They may also have an increased sensitivity to sensory stimulation which may make socialization even that much more difficult.


Delayed speech is often a sign of a developmental disability. Individuals on the autism spectrum have varying communication skills that develop at different times of life. Some individuals do not experience trouble talking, but can still have trouble communicating certain feelings. Approximately 40% of individuals with ASD do not talk at all, while others may say only single words or repeat the same phrases over and over.5 Some children experience a regression in communication after developing normally until about 12 to 18 months. Other children might not speak until later in childhood.

According to the CDC2, some examples of communication deficits related to ASD include:

  • A delay in speech and language skills
  • Echolalia
  • Reversing pronouns (using “me” instead of “I”)
  • Provides unrelated answers when asked a question
  • Failure to point or respond to pointing
  • Using few or no gestures (reaching for an object they want)
  • Often talking in a flat, robotic, sing-song voice
  • Failure to understand jokes, sarcasm, and teasing

Many individuals with autism often repeat the same words and phrases over and over, a condition known as echolalia. Fortunately, echolalia rarely extends past adolescence. Many individuals on the autism spectrum have no problem with speaking, but may find it difficult to listen and comprehend what another is saying. Also, individuals with ASD may have trouble properly using and deciphering gestures, body language, or tone of voice. For instance, it is not uncommon for individuals with ASD to smile when saying something sad.

Peculiar Interests and Behaviors

The CDC’s list2 of unusual interests and behaviors seen in individuals on the autism spectrum include:

  • Lines up toys or other objects (stacks canned foods)
  • Persistently plays with toys in the same way
  • Drawn to parts of objects (wheels of a toy car)
  • Highly organized
  • Gets upset by minor changes
  • Obsesses over the same interests (playing cards)
  • Must follow the same routines (has to brush teeth before putting on clothes or take the same route to school every day)
  • Constant movement: rocking back and forth, flapping their hand repeatedly, spinning in circles

Individuals with ASD have been known to partake in repetitive actions that can involve either the whole body or just a part of the body. These repetitive motions can even involve particular objects like switching a light on and off. A change in routine may seem catastrophic for an individual on the autism spectrum such as stopping at the grocery store on the way from school. It is common for individuals with ASD to experience “melt downs” or tantrums if forced to vary from the routine, especially if in a strange environment.

The CDC’s list2 of other symptoms often associated with autism spectrum disorders include:

  • Hyperactivity
  • Highly impulsive/acts without thinking
  • Brief attention span
  • Aggression
  • Self-injurious behavior
  • Temper tantrums
  • Peculiar sleeping and eating habits
  • Unusual mood or emotional reactions
  • Lack of fear or more fear than expected
  • Uncommon responses to the way things sound, smell, taste, look, or feel

Individuals with ASD might have unusual responses to touch, smell, sounds, sights, taste, and feel. For example, it is not uncommon for individuals with ASD to have a high tolerance to pain. Additionally, people on the autism spectrum can have very fussy eating habits, choosing to eat only few and specific foods. Digestive problems and diarrhea are also often associated with individuals on the spectrum.


Skill sets for individuals with ASD vary from person to person. Some individuals are adept at problem solving, but find it difficult to make friends, communicate, or interact socially. It is also common for individuals with ASD to have a scattered skill set; they may display high competency in one area, but less strength in a skill that may be considered simpler in nature.

Physicians stress that your child should receive a developmental checkup at 18 months of age. A child failing to achieve a developmental milestone or two by the suggested time period does not necessarily indicate your child has an autism spectrum disorder. However, if you are concerned about your child’s development or want to learn more about possible signs of autism visit the CDC checklists for developmental progress and talk with your pediatrician about your concerns.