Are down syndrome and autism the same

Autism and Down Syndrome: Similarities and Differences

Autism and Down syndrome are separate conditions, but it’s possible for a person to have both.

If you’re reading this, you might know someone with Down syndrome or someone who’s autistic. You may even know someone with a dual diagnosis of both.

Autism spectrum disorder (ASD) and Down syndrome (DS) are both complex and lifelong. Though they share some characteristics, they have more qualities that set them apart.

ASD and DS are not the same conditions, but they can occur together. About 20% of people with Down syndrome are also autistic.

There are some distinct and key differences between autism and Down syndrome.

Autism spectrum disorder

Autism is a neurodevelopmental difference that can affect a person’s abilities in language, social interaction, and behavior. People with ASD present with a broad range of traits and can seem completely different.

The Centers for Disease Control and Prevention (CDC) estimates that about 1 in 44 children are autistic.

Doctors identify autism by observing and assessing a child’s behavior and developmental history. It’s possible to spot ASD behaviors in someone as young as 2 years of age, but some autistic people aren’t identified until they’re older or even adult.

It’s usually impossible to tell that a person is autistic just by looking at them.

Down syndrome

Down syndrome is a chromosomal condition. It’s the most common genetic disorder in the United States, affecting about 1 in 700 babies born.

Medical testing called karyotyping can check for the chromosomal differences associated with DS.

It’s possible to diagnose DS before birth using prenatal karyotype testing. A doctor can also identify DS characteristics at birth during an exam and confirm with a blood test.

Multiple factors can contribute to the cause of autism, including:

  • genetics, both gene mutations and family history
  • environmental factors, such as pesticide exposure during pregnancy or birth trauma that restricted the supply of oxygen to the baby
  • biological factors, such as infection during pregnancy and inflammation

Meanwhile, Down syndrome is a chromosome disorder. It occurs more frequently in pregnancies with mothers age 35 or older.

There are three types of DS:

  • Trisomy 21. Every cell has a third copy of chromosome 21 (usually, each chromosome has only 2 copies).
  • Mosaic Down syndrome. Some cells have 3 copies of chromosome 21, and other cells have only 2 copies.
  • Translocation Down syndrome. This is when an extra piece or extra whole copy of chromosome 21 is attached to a different chromosome.

Autism and Down syndrome have some shared characteristics. In other ways, they’re quite different.

For example, many autistic people prefer to keep to themselves. They may appear withdrawn or indifferent. On the other hand, people with DS are often social and friendly.

Many autistic people don’t follow a usual pattern for learning language. Some never speak. Others learn to speak and then lose language development.

Meanwhile, the language development of people with DS is similar to that of typically developing children.

Other differences include:

AutismDown syndrome
Minimal or no use of gesturesUse of signs and symbolic gestures
May act as though other people are inanimate objectsTries to copy others
Parallel play (plays beside others)Joint attention (plays with others)

Autism exists on a broad spectrum and has various behavioral expressions. For example, some autistic people use gestures, have common language skills, and enjoy spending time with friends.

DS is also likely to cause individuals to learn and progress more slowly. ASD includes a wide range of intellectual abilities — from severe delays to gifted, or superior levels of intelligence.

Traits shared by both ASD and DS include:

  • preference for routine
  • less responsive to the sound of their name
  • expressive language differences
  • atypical eye contact
  • sensory differences
  • repetitive play
  • challenging behaviors
  • focused interests
  • anxiety
  • developmental differences
  • reduced reciprocal conversation

Autism doesn’t affect the way a person looks. However, DS causes recognizable physical changes, including:

  • upward slanted eyes
  • short neck with extra skin at the back
  • small head
  • small ears and mouth
  • white spots on the iris of each eye
  • reduced muscle tone
  • flat facial features
  • hands that are wide and short, with short fingers

Both ASD and DS usually occur with health issues. The degree to which they affect each person can vary.


  • seizures
  • gastrointestinal issues
  • sleep disorders
  • pain threshold differences
  • metabolic differences

Down syndrome:

  • congenital heart defects
  • cataracts and poor vision
  • hearing loss
  • hip issues
  • leukemia
  • obesity
  • hypothyroidism
  • constipation
  • sleep apnea
  • infection susceptibility
  • dementia
  • Alzheimer’s disease

The goal of autism treatment for children and adults is to support each individual to make daily life easier. For some autistic people, that might be speech therapy or social skills training. Others might benefit from academic support or physical therapy.

Sometimes, doctors prescribe medication to treat co-occurring conditions like attention deficit hyperactivity disorder (ADHD) or mood disorders.

Much like autism treatment, Down syndrome treatment is tailored to the needs of the individual. Many support services are similar to those provided for autism but with different objectives.

For example, a speech pathologist might help an autistic child assemble words into complete sentences. For a child with Down syndrome, the focus might be more about the clear pronunciation of those words.

In addition to the types of health and education professionals Down syndrome shares with autism, DS can also result in significant medical needs, such as surgery for heart defects and cancer treatment.

Many autistic people and people with Down syndrome lead full lives. Both diagnoses are common enough that there’s a wealth of knowledge and support available to individuals and families who need it.

The Autism Society is a place to start for information and education. The National Down Syndrome Society has useful resources and programs. The Disability Rights Education & Defense Fund can help with civil and human rights advocacy, as well as training and public policy.

Autism and Down syndrome can occur together, but because autism is diagnosed by observing behavioral differences, it may not be as noticeable in a young child with Down syndrome.

If your child with DS seems less social than others, a doctor can advise about the possibility of an ASD and DS dual diagnosis.

Autism Vs Down Syndrome: What is the Difference?

In the last few years, there has been a noticeable increase in the number of children with Down syndrome who are also being diagnosed with autism spectrum disorder (ASD). Children who have autism, as well as Down syndrome, have a dual diagnosis. They have two co-existing conditions.

Earlier, many experts and parents believed that children couldn't have autism and Down syndrome together. This concept is gradually becoming dated with the continuous publication of longitudinal research on the behavior and affects of children with Down syndrome and ASD.

As of 2021, psychiatrists diagnose approximately 1 in 44 children in the US with Autism Spectrum Disorder (ASD). Every year, around 6000 babies are born with Down Syndrome in the US. Experts working with children with Down syndrome and ASD report that approximately 18% to 20% of all children with Down syndrome also have autism.

It makes Autism Spectrum Disorder and Down syndrome equal opportunity conditions. These disorders can affect any child irrespective of their geographic location, race, and socioeconomic status. While both these conditions can be difficult to manage, a dual diagnosis poses a unique set of challenges for the parents.

While Autism Spectrum Disorder and Down syndrome are developmental conditions, they have different causes, symptoms, treatment, and management.

What Is Autism Spectrum Disorder?

Autism spectrum disorder (ASD) or autism is a complex developmental condition. Individuals with autism spectrum disorder face persistent challenges involving social communication, repetitive behavior, and limited interests. It is a lifelong condition, but the range of signs and symptoms can vary significantly between two individuals with ASD.

The diagnosis of ASD can only be made by a child psychiatrist or psychologist. Sometimes, the signs of autism become noticeable when a child is between 2 and 3 years old. In several cases, the social communication and functional deficits related to autism become more pronounced only after the child begins school.

Some of the typical social communication deficits may include –

  • Less to no interest in sharing of interest with others
  • Trouble appreciating their own emotions as well as others’ emotions
  • Difficulty in holding eye contact
  • Difficulty in making friends
  • Inflexible or robot-like speech
  • Inability to grasp abstract ideas

Individuals with ASD may also have repetitive behaviors and restricted interests. These may include –

  • Extreme difficulty in coping with change may even lead to outbursts
  • Intense focus on topics and subjects that may not intrigue their neurotypical peers
  • Hypersensitivity to loud noises, bright lights, or changes in temperature
  • Inability to accept changes to routines or new experiences
  • Stimming or repetitive movements like hand flapping or rocking back-and-forth
  • Organizing things (toys, in the case of children) in a particular fixed manner

An early diagnosis of autism may allow the child and their family to access the resources necessary for their therapy. Although ASD is a lifelong condition, early intervention can help the child develop social interaction and communication skills.

There is NO cure for autism since it is a condition and NOT a disease. However, a child may benefit from speech and language therapy, behavior therapy, social skills training, special education, and parent management training.

What Is Down syndrome?

Down syndrome or trisomy 21 is a chromosomal disorder. The presence of an extra (entire or partial) copy of chromosome 21 causes down syndrome.

It is not hereditary. However, advanced maternal age may play a role in the higher risk of a child being born with Down syndrome.

Currently, prenatal screening allows the diagnosis of Down syndrome in utero. Doctors can diagnose the condition almost immediately after birth after direct observation as well. The diagnosis of DS is quite straightforward since it's based on direct observation or genetic (chromosomal) analysis.

The severity of down syndrome varies among individuals. It may be the cause of lifelong learning disorders, intellectual disability, and developmental delays. Depending on the severity of the condition the individual may also have additional health problems such as heart defects.

Most individuals with Down syndrome have distinct facial features that may include -

  • Short neck
  • Upward slanting eyelids
  • A small head
  • Flattened face
  • Poor muscle tone
  • Short hands with a single crease across the palm
  • Small hands and feet with short fingers and toes
  • Brushfield’s spots

The facial features may also vary between individuals with down syndrome. Infants diagnosed with DS typically show a slower growth rate and are shorter than their peers as they grow older.

Sadly, most children with DS show mild to moderate cognitive impairment. They may experience speech and language delays, along with learning-memory problems.

Apart from seeking speech and language therapy for toddlers with Down syndrome, remain in touch with their pediatrician. Research shows that individuals with DS may experience health complications. These may include heart defects, defects of the GI tract, sleep apnea, disorders of the immune system, problems of the spinal column, and weight management problems.

Therefore, getting routine medical care is extremely important for anyone with Down syndrome.

Is it Autism or Down Syndrome?

Autism Vs Down Syndrome: Causes
  • Autism:  There is no determined cause of autism. Causes may be a combination of genetic and non-genetic factors.
  • Down Syndrome: Partial or complete trisomy of Chromosome 21.

Autism Vs Down Syndrome: Diagnosis
  • Autism:  Autism may be diagnosed early by a child psychiatrist or psychologist.
  • Down Syndrome: Down Syndrome can be diagnosed via prenatal testing before birth or immediately after birth through direct observation.

Autism Vs Down Syndrome: Physical Traits
  • Autism:  No physical traits are currently associated with autism
  • Down Syndrome: Down syndrome is associated with distinct physical traits like distinctive facial features.

Autism Vs Down Syndrome: Mental/Intellectual abilities
  • Autism:  Individuals with autism may have disabilities that range from learning difficulties to cognitive deficits.
  • Down Syndrome: Those with mild to moderate Down syndrome may not have overt mental disabilities.
  • Autism:  Those with autism may face difficulties in understanding social cues and communicating in social situations.
  • Down Syndrome: Those with mild to moderate DS understand social cues and participate in social communication much more easily.

Dual Diagnosis: Autism and Down syndrome

When a child already has Down syndrome, diagnosing autism spectrum disorder can be challenging. Parents of children with DS need to observe, monitor and note any changes in behavior.

Here are some new behaviors or behavior changes you should notice in a child with both autism and down syndrome –

Younger Than 3 Years –

  • Repetitive motor behavior
  • Episodic eye movements
  • Sudden and extreme refusal of specific food
  • Atypical play with toys
  • Regression of spoken language, gestures, and signs
  • Impairment of receptive language
  • Fascination with or staring at moving lights, fingers, or ceiling fans

Older Than 3 Years

  • A history of developmental regression
  • Atypical vocalizations
  • Unusual sensory responsiveness
  • Hyperactivity or hypoactivity
  • Short attention span
  • Resistance to changes in routine

Children older than 3 years with dual diagnosis may also show severe anxiety, agitation, fearfulness, and disruptive behavior in social situations. They may also experience disturbed sleep.

Signs in Teenagers

  • Lack of social response
  • Distant behavior with family or friends
  • Absence of interest to form new relationships and maintain old ones
  • Anxiety, fear, and agitation in the presence of new people
  • Fascination or obsession with inanimate objects
  • Extremely difficulty in adjusting to a new environment

Parents with children with DS should note that these behaviors are completely normal at certain points of development. Developmental regression is also expected in children with moderate to severe Down syndrome. However, when one or more of these behaviors become pervasive and extreme, your child may require an evaluation for autism spectrum disorder.

Autism in Children with Down syndrome: What Should You Do?

If you believe that your child will benefit from an evaluation, you should begin a close observation of their behaviors. When speaking with the healthcare provider, be sure to ask if they have experience with diagnosis and therapy of autism among children with Down syndrome.

It is also crucial that you remain informed as the primary caregiver. Here's what you can do to ensure that –

  1. Boost your support system. Talk to your family members, friends, family doctor, and psychologist.
  2. Learn more about autism in children with down syndrome from reliable sources.
  3. Seek the services of a professional counselor or family therapist if you find yourself struggling with difficult emotions.
  4. Join social media support groups for children with dual diagnoses.

Getting a correct formal diagnosis can help your child receive the proper school and services they need for a better quality of life.

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How are autism and Down syndrome related?


Interviews about the prevalence and features of autism in children with Down syndrome

Source: Interactive autism network at Kennedy Krieger Institute

9000 9000

have other medical conditions. These include Down syndrome, which is characterized by intellectual disability. The simultaneous presence of these two conditions creates unique challenges for families. In this interview, Dr. George T. Capone, director of the Down Syndrome Clinic at the Kennedy-Krieger Institute in Baltimore, USA, explains how the combination of these conditions affects children and what treatment approaches might be. nine0003

How common is autism among children with Down syndrome?

I can't say for sure, but approximately 5-10% of children with Down syndrome meet the criteria for an autistic disorder.

Why are children with Down syndrome so prone to autism?

No one knows the exact answer to this question. There are several different approaches to explain this phenomenon. Some believe that this is due to some concomitant medical diseases. This may be the case for infantile spasms, a type of epilepsy that occurs in very young children, and whose possible long-term consequences include autism spectrum behavior. Whatever the mechanism behind this appears to be, it has to do with how the genes on chromosome 21 interact with the other 22 pairs of chromosomes, resulting in a differently organized brain that differs from that of typically developing children with Down syndrome. (People with Down syndrome have an extra copy of chromosome 21.) nine0003

How does autism manifest itself in children with Down syndrome?

Most children in this subgroup are developmentally delayed with marked social and communication impairments and behaviors that look like autism. In this scenario, the child develops atypically, he does not share attention with other people, and he lacks social and communication skills, which becomes noticeable by the age of 15-18 months, sometimes earlier. In other cases, children develop for a time typical of children with Down syndrome, and then they regress. This regression usually occurs quite late, between the ages of three and six, unlike other children with autism who regress between 18 and 24 months. In another scenario, the child had infantile spasms, and even after the seizures were successfully controlled, the child continues to develop in an unusual way. nine0003

What is the sex ratio of children with Down syndrome and autism?

It looks like it's 3-4 to one with male predominance.

Why are children with Down syndrome and ASD diagnosed later than those with only Down syndrome or only ASD?

There are several reasons for this. Firstly, this is due to the phenomenon of regression, which occurs quite late, in the period from three to six years. Secondly, others already expect some kind of dysfunctional or atypical behavior from children with Down syndrome, especially if they have a large delay in terms of adaptive, speech and language skills. In other words, the atypical development of people who have already been diagnosed with Down syndrome is much more tolerant. It is probably worth noting that not all low-functioning children with Down syndrome have pronounced autism-like behavior, and not all children with autistic-like behavior are low-functioning. nine0003

The first step in the right direction is to abandon this logic and ask the question as follows: “If this child with Down syndrome is different from 80-85% of other children with Down syndrome, perhaps it is our duty to him and ourselves to try to figure it out what's the matter here." So for me, the first step is to reclassify the child as having both Down syndrome and ASD, which is a dual diagnosis.

What difficulties can arise in diagnosing a person with Down syndrome and ASD? nine0009

It is unclear whether standard ASD diagnostic tools, such as the Autism Observation Chart and the Autism Diagnostic Interview, can be used for people with severe or even extremely severe intellectual disability, which can occur in Down syndrome. It is difficult to separate the atypical social communication and lack of social responses in autism from other aspects of the intellectual disability in Down syndrome. This makes diagnosing autism in children with Down syndrome problematic. Another reason is that the idea of ​​having ASD in a child with Down syndrome may simply not occur to anyone. nine0003

What are the possible consequences if a person with Down syndrome is never diagnosed with autism?

The main implications are the early intervention program and individualized education program, because these children are not suitable for standard interventions for children with mental retardation, they need something more - programs to reduce maladaptive behavior, develop functional communication and daily life skills. Another aspect of diagnosing autism is that it allows you to be on the lookout for common comorbid problems—sleep disorders, anxiety and emotional disorders, and, of course, maladaptive behavior in general. nine0003

How can parents know that their child with Down syndrome may have autism?

To some extent it depends on their acquaintance with other children with Down syndrome. Parents who are involved in parent organizations and associations often see different children with Down syndrome, and they will notice if their child is very different from them. Very often, it is then that they have the first suspicions that the child may have autism. In another situation, there is a family that lives in a more isolated region, and they do not have a social circle among other parents and children. In such cases, parents risk losing the benefits of early diagnosis and interventions specifically for autism, including behavioral programs to teach functional communication and skills, or drugs. nine0003

What medications can these be?

There are medications for insomnia and to help you sleep at night. Children with increased impulsivity or uncontrollable behavior may need medications for attention deficit hyperactivity disorder. For very severe cognitive and attention deficits with strong stereotypes (repetitive movements or speech) and sensory-associated behaviors, we may try an atypical antipsychotic. I am wary of the use of stimulants and antidepressants among these children. Sometimes we resort to mood stabilizers for very irritable children with self-aggressive behavior, especially if they have a history of infantile spasms. Whatever drugs are involved, their prescription and dosage are regularly reviewed according to the individual needs of the child and any negative side effects. The question is, is it possible in principle to find a drug that can reduce this particular behavior, but will not have significant side effects? Unfortunately, this is not always possible. nine0003

What will you do if the drugs do not work or if the parents are against the drugs?

We will continue to rely on other types of autism care - behavioral therapy, sensory therapy, development of functional communication and training of school teachers to work with such children. This is not to say that you should try one approach and rule out all the others. Typically, a combination of all of the above is used. nine0003

Diagnostics and tests, Comorbidities

Down syndrome • Autism. Encyclopedia


comorbid problems and diseases

Down syndrome

is the most common disease caused by chromosome mutation

. The genetic causes of the syndrome are associated with trisomy (the appearance of another extra chromosome) on 21 pairs of chromosomes. Sometimes caused by only a piece of an extra chromosome, mosaicism is also possible (only a part of the body's cells contains the wrong set of chromosomes). Rarely (less than 1% of cases), the syndrome is caused by translocation (transfer of a portion of a chromosome to another chromosome). At the same time, in the case of Down syndrome, Robertsonian translocation most often occurs - a simple transfer of one section of the chromosome to another. nine0003

This syndrome was first described by the English physician John Langdon Down in 1862. The main symptoms of Down syndrome are intellectual disabilities and physical growth retardation. The syndrome is characterized by numerous physical defects, among which umbilical hernia, low muscle tone, brachycephaly, etc. are often found. irregular speech (unstable rhythm, poor syntax and grammar), almost 30% of children with Down syndrome have some kind of mental illness, 5-10% are diagnosed with autism spectrum disorders. Patients are also at increased risk for epilepsy, congenital heart disease, and Alzheimer's disease. More than half of people with Down syndrome have hearing and vision problems. There is an increased (10-15 times) likelihood of leukemia. There are problems with the endocrine system, most often with the thyroid gland (about 25% of all patients). People with this syndrome have reduced fertility. nine0003

Down syndrome is considered the most common chromosomal abnormality in humans. The estimated frequency of the disorder is 1 per 1000 newborns. Since there are cases caused by translocation, screening may not always detect the disease. But the detection accuracy of this syndrome is about 90-95%. Usually, an ultrasound test, a Kettering test, and an extracellular embryonic DNA test are used for diagnosis. Fetal blood tests are possible.

Causes and risk of recurrence

Parents of a child with Down syndrome are most often healthy or have diseases that are in no way associated with an increased risk of having an affected child.

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