Tourette syndrome and autism

Many behavioral manifestations of autism overlap with the diagnostic symptoms of conditions such as obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), and Tourette syndrome (TS).  Some of the shared symptoms include difficulties in settling down, shifting flexibly between tasks, organizing thoughts, and integrating details into a larger picture.  In addition, patients often exhibit repetitive behaviors like hand flapping, engaging in routines or rituals, and insistence on sameness.  The commonality of symptoms helps explain why, even though diagnosed with different conditions, patients exhibit similarities in behaviors both at school and at work, and comparable needs for treatment and accommodations.  The shared manifestations suggest an underlying disorder of self-regulation and executive dysfunction. Along those lines, a common core deficit may give rise to a spectrum of symptoms which, when modified by the individual’s environment, could give rise to different diagnoses.  In genetics this phenomenon is called “phenocopies”.  In this particular blog I will talk about one such comorbidity to autism: Gilles de la Tourette syndrome or Tourette syndrome for short (TS).

It is said that one in five children with TS has autism.  On the other hand, twenty-two percent of children with autism have tics and half of these children comply with a diagnosis of TS.  So, what is Tourette syndrome?  This is a neurological disorder characterized by involuntary tics and vocalizations.  Like autism, it begins during childhood and affects mostly males in a 9:1 ratio. Prevalence estimates suggests a TS diagnosis in 1 out of every 100 school children.

Interest in TS greatly increased in the early 1900’s when an epidemic of encephalitis (i.e., a brain inflammation often secondary to a virus) spread around the world triggering tic disorders.  The manifestation of TS as a sequel to an inflammatory brain disorder suggested an organic origin rather than a psychogenic one.  Decades later, in 1965, Dr. Arthur Shapiro treated a TS patient with haloperidol and published it as a case report.  In the discussion of the article Dr. Shapiro criticized the use of psychoanalysis as a treatment option or as an explanation of causation. 

The differential diagnosis of TS includes transient tics of childhood, movement disorders like chorea or dystonia, and those cases that come about as a side effect to the use of stimulants such as cocaine or methamphetamine.   TS can be diagnosed in anyone regardless of gender, race, or socioeconomic status.  Once you become aware of the condition, you will see that TS is quite common.  Some famous people with the disorder include Howie Mandel, Billie Eilish, and David Beckham. 

TS is highly heritable with a 50-70% concordance rate among monozygotic twins. First degree relatives have a 5-15x increased risk of developing the condition.  There is no evidence that pediatric autoimmune neuropsychiatric disorders associated with strep infection (PANDAS) play a role in the development of TS.  Risk factor for TS include having ADHD, OCD, other mood/anxiety disorders, and obstetrical complications such as low birth weight and maternal smoking during pregnancy. 

Tics are the hallmark of the disorder, with an onset between 4 and 10 years, reaching a peak in severity between 8 and 12 years.   Tics can be motor (progressing in a head-to-toe direction) or vocal.  Simple motor tics may involve a limited group of muscles (e.g., grimacing), while complex motor tics involve a larger number of muscles (e.g., body twisting). Vocal tics can be simple (e.g., throat clearing, sniffing) or complex like making obscene utterances (coprolalia).  Tics occur in bouts, and wax and wane over time, but begin to decline during adolescence. There are premonitory urges with frequent, uncomfortable sensations that are relieved by their completion. These urges may be more distressing than the tics themselves.  If the patient experiences discomfort or social problems, mild cases can be treated with education and support.  Potential interventions include habit reversal therapy, exposure and response prevention (ERP) and comprehensive behavioral intervention. Pharmacotherapy in TS includes clonidine and guanfacine (alpha 2 agonists) and benzodiazepines.  Haloperidol and pimozide are both FDA approved for treatment of severe cases.

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