Some autistic people are usually able to speak, but lose their ability to speak when subject to stress or exhaustion. It has become common in the online autism community to refer to these non-speaking episodes as “selective mutism”, due to a concern that calling it “non-speaking” or “non-verbal” is offensive to those with more severe autism.

As I will explain below, it is incorrect to use the term “selective mutism”, for three reasons:

• selective mutism is a specific mental disorder with a diagnostic process, not just a term you can apply anywhere it sounds right;
• autistic people’s non-speaking episodes do not fit the DSM-V diagnostic criteria for selective mutism;
• the DSM-V criteria specifically state that you cannot diagnose selective mutism in an autistic person even if the symptoms do match.

Firstly, “selective mutism” is not simply a phrase meaning “sometimes can speak and sometimes can’t”. It is a mental disorder listed in the DSM-V. If someone hasn’t been diagnosed with selective mutism, or hasn’t made sure the diagnostic criteria apply to them in the case of self-diagnosis, you shouldn’t apply the term to them. The definition and criteria for selective mutism are linked here.

Secondly, the diagnostic criteria for selective mutism are not consistent with the non-speaking episodes suffered by autistic people. Here is Criterion A from the DSM-V:

Consistent failure to speak in specific social situations in which there is an expectation for speaking (e.g. - at school) despite speaking in other situations.

This is what is meant by “selective”, that the inability to speak only happens in certain social contexts. This is not true for autistic non-speaking episodes, which typically involve being unable to speak in any context, even to family and close friends. When the episode is over they regain the ability to speak in all contexts. This is not what the selective mutism checklist is describing.

Next is Criterion C:

The duration of the disturbance is at least 1 month (cannot be during first month of school).

Again this obviously does not apply to autistic people, whose temporary inability to speak may only last a few weeks, days or even a few hours.

The prognosis section notes that selective mutism is mostly found in children and most children grow out of it. This also does not describe the experience of autistic people.

But thirdly and most importantly, it is literally impossible to have both autism and selective mutism. Even if the above criteria do apply, along with Criteria B and D, this is what Criteria E says:

The disturbance is not better explained by a communication disorder (e.g. - childhood-onset fluency disorder) and does not occur exclusively during the course of autism spectrum disorder, schizophrenia, or another psychotic disorder.

Obviously autism spectrum disorder is a lifelong disorder, so anything that happens in your life occurs “exclusively during the course of autism spectrum disorder”. Therefore no one with ASD can be diagnosed with selective mutism.

They do not need to be diagnosed with a disorder to explain language and communication problems, because those problems are explained by the diagnosis of autism spectrum disorder.

As for what these non-speaking episodes should be called. The term “non-verbal” is not accurate since it means “without words” or “without language”. Indeed, it is rarely accurate even when used to describe permanently non-speaking adults, who are often able to understand speech, read and write, and who often prefer the term “non-speaking”.

In this post I have been using that term “non-speaking episodes” because it factually describes what is happening. Some people suggest “autistic shutdown” which is common in the community.