Is it Autism, Selective Mutism, or both?

Selective Mutism can sometimes be mistaken for Autism because they can share overlapping symptoms. What is the difference between the two conditions and can they coexist?

What is Autism?

Autism, also referred to as autism spectrum disorder, is a lifelong neurological and developmental condition that affects how a person interacts with and experiences the world around them. It is considered a spectrum disorder because each person has their own strengths, challenges and support needs. Autism can vary greatly and no two individuals are the same.

Signs of Autism include (though not limited to):

• Differences or difficulties in social communication/social interaction.
• Difficulty understanding or interpreting nonverbal and verbal social cues.
• Displaying repetitive behaviours or rigid routines.
• Becoming deeply fixated on certain interests or topics.
• Sensory sensitivities including both hypersensitivity (over-responsiveness to stimuli) or hyposensitivity (under-responsiveness to stimuli).

What is Selective Mutism?

Selective Mutism (sometimes referred to as Situational Mutism) is an anxiety disorder where a person is unable to speak in certain social situations, while being able to do so freely in others. It is an intense anxiety around communication, and it is linked to the body’s freeze response. Their silence is not a choice. A person wants to speak but is physically unable to do so.

Selective Mutism can start at any age, but it typically starts in early childhood between the ages of 2 to 4, and with the right support, a child can overcome their anxiety. However, the condition can also affect adolescents and adults.

Selective Mutism often co-occurs with social anxiety disorder and studies suggest that there is a strong overlap between the two.

Signs of Selective Mutism can include:

• Inability to speak in certain social settings such as at school despite being able to do so at home or with close family/friends.
• When expected to speak, individuals may appear frozen, tense or expressionless.
• May rely on nonverbal communication such as nodding, pointing or writing.
• Appearing shy, withdrawn or disinterested.
• A clear difference in behaviour at home vs in school/social settings.

Overlapping Symptoms and the Difference

Selective Mutism and Autism can share some similarities such as:

• Appearing shy or withdrawn
• Difficulty interacting or engaging in social settings
• Freezing and/or shutting down
• Struggling to make eye contact
• A preference for predictability and/or familiarity
• High anxiety
• Sensory difficulties

While children with Selective Mutism can present with similar behaviours that can look like autism when they are anxious, it is fundamentally different from autism, and a key difference is that SM is context dependent. Autism is pervasive meaning that traits are generally present across all settings and affects a much broader aspect of a person’s life.

On the surface the two conditions can sometimes look similar and because of how the anxiety often manifest in public settings, children with selective mutism can in some cases be misdiagnosed with autism. This was my experience as a child. Professionals may assume that the child is autistic but fail to recognise that the primary driver behind the child’s silence is rooted in anxiety.

A personal experience

When I was around 9 years old a psychologist who worked closely with the school that I attended, came over to my house to conduct some tests with me because I was not speaking at school. She then reported to my parents and the school that I was autistic. The school went with what this psychologist said, but my parents did not believe so as I have never showed any signs of autism. We were later sent to a children’s psychological clinic and the psychologist who we met with confirmed that I was not autistic, but that I was showing signs of Selective Mutism instead.

It is important that a comprehensive evaluation and thorough assessment is made to determine or rule out a diagnosis. Observing a child in a situation or environment that is anxiety inducing and where they are not speaking can be helpful but often it is not enough.

Could it be both?

Historically, many professionals (some still today) treated the two conditions as mutually exclusive because of diagnostic guidelines or criteria. However, the truth is that selective mutism and autism spectrum disorder can and do often co-occur. Research and estimates may vary, but they do indicate a significant overlap and co-occurrence between the two, with some studies suggesting that 63%-80% of children diagnosed with selective mutism also meet the diagnostic criteria for autism.

For some children a co-occurring diagnosis can sometimes be delayed because of symptoms being missed or overlooked or because of diagnostic overshadowing. Selective Mutism can also be missed in some children who are autistic because the child may be viewed as “just shy” or “very quiet”, or professionals may fail to realise that a child’s inability to speak is anxiety based and not solely due to autism.

Autistic individuals are also more likely to experience anxiety disorders than non-autistics due to a combination of factors such as navigating social and communication challenges and a high intolerance for uncertainty. For some autistic individuals the anxiety surrounding social situations and communication can then express itself through selective mutism and/or social anxiety disorder.

Autistic Shutdown or Selective Mutism?

Selective Mutism is also different from autistic shutdowns where a person may temporarily lose the ability to speak due to stress, overwhelm, or sensory overload, etc. It is only considered to be Selective Mutism if the pattern of mutism is consistent and context-dependent. An autistic shutdown can sometimes be mistaken for SM, but it is important to recognise that they are not the same. Shutdowns may not follow a consistent pattern and can happen regardless of comfort level.

To Summarise…

Selective Mutism in itself is not an indicator for Autism.

Not everyone who is Autistic also has Selective Mutism.

Understanding that they are two distinct conditions but also recognising that the two can coexist is crucial so that individuals can receive the right support.