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What are The Similarities Between Autism and Down Syndrome?

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The most recent research indicates that between 8% and 18% of people with Down syndrome also have autism spectrum disorder (ASD).

Additionally, upwards of 25% of individuals with Down syndrome have some symptoms of autism but not with enough prevalence to be diagnosed with the neurological disorder.

Scientific research indicates that autism occurs more often in people who have other genetic or chromosomal irregularities, such as Down syndrome.  

Yet regardless of the statistics, at Heartlinks, we still have many parents who remain unclear as to the differences and similarities between autism vs. Down syndrome.

They falsely believe the two are the same condition or that if their child is diagnosed with one, they must automatically have the other.

Down syndrome and ASD are both persistent and complex medical diagnoses with some similarities yet more significant differences.

It’s time to set the record straight.

Autism Explained

Young Teacher Painting at a Desk with a Boy with Down Syndrome

ASD, or autism spectrum disorder, is a neurodevelopmental condition. It can affect a child’s abilities with social interaction, language, and overall behavior. 

Currently, 1 in 44 children are diagnosed with ASD here in the United States. An autism diagnosis is made by a child’s doctor or a team of specially trained individuals (i.e., psychologist, psychiatrist). 

The symptoms and signs of autism in children are wide-ranging. They can include a few or many of the following:

  • Little to no eye contact with others
  • Inability to respond to their name
  • A lack of similar interests to their peers
  • Repetitive hand movements or body gestures
  • Difficulty with social interactions
  • Limited language skills that develop but then stop or regress
  • Becoming withdrawn socially and physically
  • Unique ways of moving, paying attention, or learning

A child with autism will exhibit unique symptoms and levels of severity from high to low functioning. 

Children with autism spectrum disorder can be diagnosed by the age of 2 at the earliest.

Down Syndrome Explained

Happy Child Smiling at School

As the most prevalent genetic disorder in the U.S.A., Down syndrome affects approximately 1 in 700 babies born in this country. 

Down syndrome is a chromosome disorder occurring during the cell division period of fetal development. While this division occurs, the abnormal cell division results in a third chromosome, leading to physical and neurological abnormalities.

Though the severity of DS varies per individual, it can be broken down into three types:

  • Mosaic Down syndrome: This type of DS occurs when specific cells have three copies of chromosome 21 while others have a mere two copies.
  • Translocation Down syndrome: With this version of DS, either a whole copy or an extra piece of chromosome 21 is attached to an altogether different chromosome.
  • Trisomy 21: Typically, each cell has only two copies of chromosome 21, but in this case, each cell has a third copy.

The distinguishing factor for children with Down syndrome is the recognizable physical differences. They include the following:

  • Upwards slanted eyes
  • Flat facial features
  • Small ears and mouth
  • Tiny head
  • A short neck with supplemental skin in the back
  • Both eyes have visible white spots on the iris
  • Reduced muscle tone
  • Short fingers and hands in comparison to the rest of their body

Other symptoms include intellectual difficulties, developmental delays, heart and gastrointestinal conditions, and learning disabilities.

The Similarities Between Down Syndrome and Autism

Communication Issues

One of the most prominent similarities between autism vs. Down syndrome is that both conditions negatively affect a child’s ability to communicate. 

Children with either of these diagnoses struggle to communicate effectively. This makes it difficult for them to express their feelings and thoughts and understand other people’s emotions. 

Whether your child has Down syndrome or autism, both conditions can leave children with a limited vocabulary or the ability to make only inaudible sounds as compared to entire sentences. 

Troubled Social Interactions

A related challenge for children with autism or Down syndrome is they have difficulty picking up on the social cues of others. Hints such as facial expressions, tone of voice, and body language are often misunderstood or overlooked by children with either condition.

A lack of understanding of these cues means that these kids often misunderstand what is being expressed to them, or their responses to certain situations seem insensitive (i.e., a friend is crying, and your child reacts by laughing).    

Sensory Sensitivities

Flashing lights, strong smells, or loud crowds of people are just a few examples of the types of situations that can cause sensory overload for autistic and children with Down syndrome.

Also known as a sensory processing disorder, sensitivity to one or many different types of stimuli is not unique to children with either Down syndrome or autism. However, it is a shared symptom of either condition that impairs how the brain interprets and reacts to new sensory information or its capacity for sensory processing.

The Differences Between Autism and Down Syndrome

There may be various similarities between these two conditions. However, there are significant differences in autism vs. Down syndrome.


Autism spectrum disorder is a neurodevelopmental difference with several different causes, including the following:

  • Family history
  • Biological factors (i.e., infections or inflammation during pregnancy)
  • Genetics
  • Gene mutations
  • Environmental factors (i.e., trauma at birth, pesticide exposure during pregnancy)

Children can be diagnosed with autism usually no earlier than age two.

Down syndrome is a chromosomal condition that can be identified at a particular stage of gestation. Unlike autism, there are no environmental factors, including toxins or carcinogens, that can cause Down syndrome.

Translocation Down syndrome can be inherited, but that happens in rare cases.

Children are typically diagnosed with Down syndrome at birth.

Physical Appearance 

A second significant difference between autism and Down syndrome is a person’s physical appearance. 

Children with Down syndrome have distinctive physical traits, including slanted eyes, flat facial features, and a short neck, to name a few. 

Unlike the former, autistic kids do not share a similar physical appearance to each other.  Their condition cannot be identified based on physical characteristics alone. Instead, they share related behavioral attributes.

Helpful Therapies for Autism and Down Syndrome  

Many different therapies can benefit a child diagnosed with autism or Down syndrome. What is most important is early intervention concerning the diagnosis. The earlier the diagnosis, the quicker therapy can begin, and the more positive the outcome will be regarding your child’s development and level of independence.

ABA Therapy

ABA (Applied Behavior Analysis) therapy is a tried and truly individualized treatment. 

At Heartlinks, we use ABA to help our young clients learn new skills and desirable behaviors

The appeal of ABA is that it can be tailored to meet the unique needs of each child, whether they have autism, Down syndrome, or both!

Speech Therapy

This treatment focuses on improving a child’s communication skills, which is an area of difficulty for those with autism and Down syndrome. Regardless of your child’s diagnosis, their speech and communication-related challenges vary significantly, from being unable to hold a conversation, reading social cues, and misinterpreting facial expressions.

A speech therapist has a range of training to help increase a child’s vocabulary, ameliorate their pronunciation, and use other forms of communication if they’re nonverbal (i.e., sign language or assistive technology).

Speech therapy aims to help the individual communicate in more functional and valuable ways. 

Occupational Therapy

Being able to perform everyday tasks independently is something many non-disabled people take for granted. However, if you have a child with either autism or Down syndrome, they may have limited fine motor skills or are unable to perform self-care tasks. These are symptoms of both conditions. 

Early intervention in the form of occupational therapy can make a tremendous difference in a child’s life. By providing the needed guidance and support, young people with either condition can lead happy and independent lives.

Heartlinks Can Help

Despite the differences in autism vs. Down syndrome, there is one overriding similarity: both are life-long conditions that require ongoing therapy and support. 

Whether your child is diagnosed with Down syndrome or autism, there is a wide variety of information and help available for them and your entire family.

At Heartlinks, we aim to assist all of our families in getting the diagnosis and treatment they deserve.


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