Down syndrome and autism spectrum disorder can both involve a need for additional support. However, these are distinct diagnoses with different underlying causes and presentations.
Down syndrome (DS) and autism spectrum disorder (ASD) are both developmental disorders, conditions present from childhood that affect typical growth and development.
While DS and ASD may both require additional support and can share symptoms related to developmental delay, important differences set them apart.
Although they both fall under the broad category of developmental disorders, DS and ASD are separate conditions.
DS affects approximately
DS is a genetic disorder, while ASD is a neurodevelopmental disorder. Their specific classifications indicate their primary difference — underlying cause.
Underlying causes
DS is caused by the presence of an extra (full or partial) copy of chromosome 21. Rather than 46 chromosomes total, 23 from each parent, children with DS have 47 chromosomes.
Because chromosome 21 contains genes that influence aspects of whole-body development, having an extra copy leads to a specific set of symptoms that differentiate DS from other developmental conditions.
The causes of ASD are not as well understood and can’t yet be traced to a single underlying factor. As a neurodevelopmental disorder, alterations in brain function and structure are responsible for ASD symptoms. But it isn’t clear why these changes occur.
A complex dynamic of genetic predispositions and environmental factors is thought to influence the development of ASD.
Symptom variety
The different causes of DS and ASD result in unique symptom presentations, even though both conditions can involve general developmental challenges.
In DS, chromosome 21’s role in development affects more than just the brain. For example, chromosome 21 contains genes related to muscle tone and growth that influence physical appearance.
This is why DS is associated with common physical traits. Children living with DS may also experience physical challenges related to atypical organ development or immune and metabolic dysfunction.
ASD, on the other hand, stems from altered brain function that impacts the way you perceive and interact with the world around you. Its symptoms primarily involve cognitive and behavioral challenges.
While ASD can feature physical symptoms like challenges with coordination or
Simply put, DS can affect the development of multiple systems in the body, including the brain, while ASD is only associated with altered brain development.
DS can be tested for at birth with genetic screening, regardless of symptoms. ASD can be diagnosed as early as 15 months old.
ASD, however, is typically recognized as children get older, and symptoms are seen through persistent behavioral patterns.
DS features physical, cognitive, and developmental symptoms. These can vary in presentation but often include:
Cognitive and developmental symptoms
- mild to moderate intellectual disability
- short attention span
- impulsiveness
- delayed language development
- taking longer to reach developmental milestones, like standing or walking
Physical symptoms
- shorter height
- poor muscle tone or loose joints
- flattened facial features
- almond-shaped eyes with an upward slant
- smaller features, like hands, feet, and ears
- a palmar crease (single, deep line across the palm)
- Brushfield spots (white spots on the colored part of the eye)
People living with DS are also
ASD symptoms are seen across areas of communication, social interaction, and restrictive/repetitive behavior. ASD is referred to as a spectrum disorder because symptoms vary significantly in both presentation and severity.
Communication and social symptoms
- not making or keeping eye contact
- appearing distracted when someone is talking
- being unresponsive to the attention of others
- infrequently sharing emotions
- talking at length about favorite topics without regard to others’ reactions
- displaying expressions or movements that don’t align with what’s said
- finding it difficult to understand someone else’s perspective
- not being able to adjust to different social settings
- finding it difficult to make friends or share in imaginative play with others
Restrictive and repetitive behavior symptoms
- repeating words or phrases
- hyper-focus on areas of special interest
- sensory sensitivities
- becoming upset by changes in routines
- finding it difficult to transition between tasks
- being able to retain detailed information for extended periods of time
Intellectual disability, or limitations in high-level thought processes like abstract thinking and reasoning,
According to a
Being diagnosed with DS
The increased risk may come from shared genetic pathways that predispose you to ASD if you were born with DS.
Signs of autism in Down syndrome
You can be diagnosed with both ASD and DS. When two distinct conditions occur together like this, it’s known as “comorbidity.”
Diagnosing ASD comorbid with DS can be challenging due to overlapping symptoms and the varied presentations of ASD.
During a comprehensive evaluation for comorbidity, your child’s developmental specialist will look for communication, social, and behavioral signs that are more aligned with ASD.
They will also assess signs that typically become more pronounced when ASD and DS occur together, such as:
- repetitive speech patterns
- heightened sensory sensitivity
- difficulty making and keeping friends
- disinterest in socializing with others
- emotional outbursts
Both ASD and DS involve individualized care that takes into consideration your specific symptoms and experiences. Under either diagnosis, finding the right level of emotional and functional support is the ultimate goal.
ASD and DS interventions help children develop new skills related to social interactions, communication, and adaptive functioning. They can include:
- behavioral therapies
- physical therapy
- occupational therapy
- speech-language therapy
- educational supports
- family education
Children living with DS may also need regular medical check-ups to manage other health conditions related to DS, like heart abnormalities or visual impairment.
While there are no medications that treat DS or ASD directly, medications may be used to help manage secondary psychological or physical symptoms.
DS and ASD are distinct diagnoses. They often share overlapping developmental delays but are differentiated by causes and symptom variety.
As a genetic disorder, DS can affect the development of multiple systems in the body. Its symptoms are physical, cognitive, and developmental.
ASD, as a neurodevelopmental disorder, is caused by altered brain function that results in cognitive and behavioral symptoms. However, secondary physical challenges are possible.
While there’s no cure for ASD or DS, the right emotional and functional support can help children successfully build skills for everyday life.