Tourette syndrome and Autism

Gilles de la Tourette syndrome or Tourette syndrome (TS) is a neurological disorder characterized by sudden, brief, repetitive, involuntary (unwanted) movements or vocal sounds called tics. They can range from mild to severe. Severe symptoms might significantly interfere with communication, daily activities and quality of life.

Tics can be classified as:

• Simple tics: they involve a limited number of muscles.

• Complex tics: they involve several muscle groups.

Motor tics in TS:

• Simple motor tics include eye blinking and other eye movements, nose twitching, mouth movements, facial grimacing, shoulder shrugging and head, shoulder or limbs jerking.

• Complex motor tics include facial grimacing combined with a head twist and a shoulder shrug, sniffing, touching objects and other people, hopping, jumping, bending, twisting or stepping in a certain pattern. (Some of the most disabling tics include motor movements that result in self-harm such as, e.g., punching oneself in the face.)

Vocal tics in TS:

• Simple vocal tics include repetitive throat clearing, sniffing, coughing, tongue licking, barking, or grunting sounds

• Complex vocal tics may include repeating random words or phrases, repeating others’ words or phrases (echolalia), or more rarely, using vulgar, obscene, or swear words (coprolalia). (Swearing is rare and only affects about 1 in 10 people with Tourette's syndrome.)

Most people with TS experience an urge or sensation (known as a premonitory urge / sensation) before a tic, which has been compared to the feeling one experiences before needing to itch or sneeze, and a strong need to complete a tic in a certain way or a certain number of times to relieve the urge or decrease the sensation. They can’t resist it: they must complete the tic to release these sensations.

Tics can change over time, varying in type, frequency and severity. They first usually appear in childhood between the ages of 2 and 15 generally in the head and neck area and may progress to include muscles of the trunk and arms and legs. Motor tics usually occur before vocal tics do, and simple tics often precede complex tics.

Most people with TS experience their worst tic symptoms between 8 and 12 years but by the late teens to early 20s, tics typically decrease and/ or become controlled. Tics may become worse if the person is stressed, anxious, or tired. In some cases, tics may worsen in adulthood. For some people, TS can be a chronic condition with symptoms that last into adulthood.

There is no cure for TS, but (mostly behavioural) treatments (such as, for example: habit reversal therapy and exposure and response prevention) are suggested to help manage some symptoms. With great effort, some people with TS suppress or stop a tic for a short while in certain social situations. With practice it gets easier. (However, they may have a sudden release of tics after a day having had to control them.)

What causes TS?

The exact cause of Tourette's syndrome is unknown. What we know is that TS is highly heritable, and it is linked to a part of the brain that helps regulate body movements.

Boys are several times more likely than girls to develop TS.

Disorders Associated with TS

TS can co-occur with other disorders/ conditions, such as, for example: attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD), autism, learning disability, sleep disorders, depression, anxiety and some others.

Although most individuals with TS experience a significant decline in motor and vocal tics in early adulthood, the associated neurological conditions continue into adulthood.

Tourette syndrome and autism

Many autistic symptoms overlap with the diagnostic symptoms of TS. In addition to sharing some symptomatology, ASD and TD are commonly comorbid (Capuano, Valeri 2016; Hanks et al. 2015). Both ASD and TS are neurodevelopmental disorders with genetic etiologies that are more common in males and characterized by repetitive motor behaviours. However, they also have many differences, such as the age of onset or the functional use of stereotypies in ASD. The co-occurrence of ASD and TS is around 4–5% and the co-occurrence of ASD and TD ranges from 9–12% (Kalyva E, et al. 2016).

Perhaps one of the most intriguing questions regarding TS and ASD is that even though interneuron pathology is described in the cortico-striatal circuits in both neurodevelopmental disorders, individuals with TS do not develop social deficits. Given that people with TS have cortical abnormalities in somatosensory, orbital and medial cortex similar to those reported in ASD, there must be an additional disturbance in the neural circuits of autistic people to produce these additional symptoms. (Rapanelli, M. et al. 2017).