Tourette is estimated to affect one in every 100 schoolchildren. Autism spectrum disorder is estimated to be 1% to 2% of the population. Some researchers suggest 6% to 8% of children and adolescents with autism spectrum disorder (ASD) have Tourette syndrome (TS).
Are Tourette and autism linked?
Tourette and autism have their own set of diagnostic criteria, yet there is a notable overlap in certain symptoms.
According to this Spectrum News article, four conditions tend to co-occur and seem to be on a spectrum:
More than half of people with Tourette also have obsessive-compulsive disorder (OCD) or ADHD, and up to 20 percent have autism. Because all four conditions can involve impulsive and compulsive behaviors, some scientists have proposed that they exist along a spectrum, with ADHD on one end, OCD on the other, and autism and Tourette in the middle.
This Center for Disease Control and Prevention (CDC) article states that 21% of children diagnosed with Tourette had autism spectrum disorder.
Some researchers place both Tourette and autism on a spectrum, and there is a certain percentage of people having both Tourette and autism.
Can autism cause Tourette, or can Tourette cause autism?
Researchers will keep studying the underlying causes and potential connections between Tourette and autism, and having one condition does not directly cause another.
Each condition has its own genetic, neurological, and environmental factors that contribute to its development.
One doesn’t cause the other, but it would be fair to say that having one would raise the possibility of having the other. It would also be wise to look into this link to help answer questions and understand why certain behaviours or symptoms occur!
Similarities in Tourette and autism
Both conditions consist of symptoms and behaviours that usually start in childhood. Both conditions seem to affect males more, with a male to female ratio of 3:1 in Tourette and 7:1 in autism.
This ratio may change over time as ‘the clinical phenomenology between sexes has not been fully examined‘.
As an individual can have both Tourette and autism concurrently, it may be hard to differentiate between the two.
Dan over at The Aspie World is a YouTuber with autism. He states in the video below (around the 3:40 mark) that it would probably be difficult to diagnose Tourette in an autistic person, because autistic people also have tics.
Do autistic people tic?
This NIH study looks at tics in individuals with ASD:
Tics are common in people with autism spectrum disorder (ASD). However, their phenomenology and characteristics have not been studied in detail.
So it seems apparent tics are experienced by some autistic people.
But, are all tic-like motor and vocal actions actually tics?
The difference between tics and stimming
The National Autistic Society describes stimming:
Stimming or self-stimulating behaviour includes arm or hand-flapping, finger-flicking, rocking, jumping, spinning or twirling, head-banging and complex body movements.
The definition makes it difficult to tell stimming and tics apart.
The table below separates tics from stimming, although they do still seem similar!
| Aspect | Tics (TS) | Stimming (ASD) |
|---|---|---|
|
Definition |
Involuntary, sudden, repetitive movements or sounds. |
Self-stimulatory behaviors that are repetitive. |
|
Purpose |
Involuntary, often following a premonitory urge. |
Often self-soothing, self-regulatory, or expressive. |
|
Frequency |
Can vary in frequency, intensity and duration. |
Can be frequent and repetitive. |
|
Types |
Motor tics (physical movements) and vocal tics. |
Wide range of behaviors, including hand-flapping, rocking, spinning objects and vocalizations. |
|
Onset |
Typically begin in childhood, often around ages 5-10 |
Can be present from early childhood. |
|
Control |
Generally involuntary, although some can be supressed temporarily. |
Usually self-initiated and can be consciously controlled to some extent. |
|
Impact on life |
Can cause social and emotional challenges. |
May help with self-regulation but can interfere with social interactions. |
One main difference seems to be the premonitory urge.
This is the involuntary and unwanted urge that occurs before a tic for many people with Tourette. This is often described as feeling like an itch, a sneeze or a hiccup.
More research needs to be done
The NIH study quoted earlier in the article states that the phenomenology and characteristics of tics in ASD have not been studied in detail.
Further study would help those of us with Tourette, autism or both to better understand our lived experience and ways to enhance quality of life.