Tourette syndrome

• 1. Introduction

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  Tourette syndrome was once considered so rare that in 1972 the US National Institutes of Health believed fewer than 100 cases existed in the entire United States. A registry from 1973 listed only 485 cases worldwide. Those numbers now look strikingly small. About 1% of school-age children are estimated to have Tourette's, and census data from around the turn of the century turned that figure into half a million children in the United States.

  Tourette's begins in childhood or adolescence and involves tics, which are sudden, repetitive movements or sounds. Most people who have it are mild enough that casual observers never notice anything. How did a condition counted in hundreds turn out to be this common? Why do some people with it never realize they have tics? And why does the one symptom most people associate with it appear in only a minority? The place to start is with what a tic actually feels like from the inside.

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• 2. Tics and Urges

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  About 90% of people with Tourette's eventually notice an urge that arrives just before a tic, much like the urge to sneeze or scratch an itch. People describe it as a buildup of tension, pressure or energy. They release it on purpose, often until the sensation feels "just right." The urge usually sits in the body part that is about to tic. A feeling of something in the throat leads to throat clearing. A localized discomfort in the shoulders leads to a shrug. Children notice the urge less than adults do, but by the age of ten most children recognize it.

  Because the urge comes first, a tic can sometimes be held back for a while. That is why tics are called semi-voluntary rather than strictly involuntary. Holding one back has a price. Suppression often brings tension or mental exhaustion, and tics may surge after a long stretch of suppressing them at school or work. Some people look for a secluded spot to let them out. A child may hold tics in during a doctor's visit, so clinicians sometimes need to watch a child who does not know they are being watched.

  The tics themselves are nonrhythmic and keep shifting. They change in number, strength, location and complexity, and each person has a unique pattern of rises and falls. Within a busy stretch there can be short bursts, which are sometimes described as "bouts of bouts." Stress, fatigue, anxiety and illness can all make tics increase. So can relaxing in front of the TV. Absorbing activities, such as playing a musical instrument, can quiet them.

  Blinking, coughing, throat clearing, sniffing and facial movements are the common tics. The tics that involve speech draw far more attention. Coprolalia is the spontaneous utterance of taboo or socially objectionable words, and it is the most publicized symptom. Only about 10% of people with Tourette's have it, and it is not required for a diagnosis. Echolalia means repeating other people's words, and palilalia means repeating your own. Both occur in a minority. The motor counterparts are copropraxia, meaning obscene or forbidden gestures or inappropriate touching, echopraxia, meaning copying another person's actions, and palipraxia, meaning repeating one's own movements. How all of these change across a lifetime follows a surprisingly regular course.

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• 3. Childhood Course

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  The typical first tic appears between the ages of five and seven, although onset can occur any time before eighteen. It usually affects the head, face or shoulders, with blinking, facial movements, sniffing or throat clearing. Vocal tics often arrive months or years after the motor ones, though they can come first. In people with more severe tics, complex ones may develop, including "arm straightening, touching, tapping, jumping, hopping and twirling."

  A 1998 study from the Yale Child Study Center found that tic severity climbs with age until it peaks between eight and twelve. After that it falls steadily for most children. Half to two-thirds see a dramatic decrease as they pass through adolescence.

  Consider ten children at the average age of peak severity, around ten or eleven. Almost four of them will be in complete remission by adulthood. Another four will have minimal or mild tics. The remaining two will have moderate or severe tics, though only rarely worse than in childhood.

  A video study of adults complicates that happy picture. It found that nine out of ten adults still had tics, and half of those who considered themselves tic-free showed evidence of mild ones. For a small group the opposite happens. Some of the most severe and debilitating forms of tic disorder are found in adults. What looks like adult-onset tics can also be childhood tics resurfacing.

  Tourette's is three to four times more frequent in males than in females, and most studies have focused on males. A 2021 review suggested that females may peak later than males, with less remission over time and more anxiety and mood disorders. Whatever the severity, life span is normal, and the condition is not degenerative. Severity early in life does not predict severity later, so doctors can judge the likely course more reliably by the age of fourteen to sixteen.

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• 4. Companion Conditions

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  In specialty clinics, 30% of people with Tourette's also have mood or anxiety disorders or disruptive behaviors. Clinic numbers need caution, because people with mild symptoms are rarely referred. Studies drawn from clinics therefore lean toward severe cases, where ADHD and OCD are often found. Those companions frequently cause more impairment than the tics do. That is why clinicians work to tell them apart and treat them.

  Estimates of pure Tourette's, with no other condition, run from 15% to 57%. Children and adolescents with pure TS do not differ from their peers on ratings of aggression or conduct problems. Add ADHD and the picture shifts. Conduct disorder and oppositional defiant disorder become more common. Angry outbursts track with the ADHD rather than with how severe the tics are, and anger control problems are more likely when OCD and ADHD are both present.

  OCD with tics is hypothesized to be its own subgroup. Where typical OCD centers on contamination, the tic-related form brings more "counting, aggressive thoughts, symmetry and touching." Those compulsions are also more likely to answer a premonitory urge than an anxious obsession.

  Between 2.9% and 20% of clinic patients with Tourette's had autism spectrum disorders. One study suggests the link is partly an illusion. Tic-like behaviors and OCD symptoms seen in autistic people are hard to separate from true tics.

  Children with only Tourette's are faster than average for their age on timed tests of motor coordination. Overall there are no major impairments in neuropsychological function. Constant tic suppression may even build inhibitory control, which could help with switching between tasks. Handwriting difficulties are common. Learning disabilities remain debated, because older studies that reported high rates did not control well for companion conditions.

  Sleep disorders and migraine also turn up more often than in the general population. That is why a careful evaluation of someone with Tourette's screens broadly.

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• 5. Genes and Circuits

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  Twin studies give the clearest hint of inheritance. Between 50 and 77% of identical twins share a Tourette's diagnosis, against 10 to 23% of fraternal twins. Close family members are 10 to 100 times more likely to have it than the general population. Yet no single gene has been identified, and hundreds are likely involved. Genome-wide studies published in 2013 and 2015 found nothing that reached significance. A 2019 meta-analysis found a single locus on chromosome 13, but broader samples did not confirm it.

  A few rare, highly penetrant mutations in the SLITRK1, HDC and CNTNAP2 genes explain only a small number of cases in single families. Not everyone who inherits the vulnerability shows symptoms. Environment seems to shape who does. Risk rises with paternal age, forceps delivery, stress or severe nausea in pregnancy, and use of tobacco, caffeine, alcohol or cannabis during pregnancy. Premature babies with low birthweight or low Apgar scores are also at greater risk. In premature twins, the one with lower birthweight is more likely to develop Tourette's.

  The hypothesis called PANDAS proposes that an autoimmune reaction after a streptococcal infection triggers tics or OCD in some children. It remains controversial. The newer PANS hypothesis and PANDAS are both under research and both unproven.

  Inside the brain, tics are believed to come from dysfunction in the thalamus, the basal ganglia and the frontal cortex. Loops called cortico-striato-thalamo-cortical circuits carry information from the cortex through the basal ganglia. They help regulate planning, movement control, decision-making and learning. Faults in these loops may explain both the tics and the premonitory urges.

  The caudate nuclei may be smaller in people with tics. Children with Tourette's have a larger prefrontal cortex, which may be an adaptation that helps regulate tics. Tics probably fade with age as the frontal cortex gains capacity. Dopamine release in the basal ganglia is higher in people with Tourette's. Histamine and its H3 receptor may play a role too, and postmortem studies have pointed to dysregulated neuroinflammatory processes.

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• 6. A Diagnostic Puzzle

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  No blood test or scan can confirm Tourette's. The fifth revision of the DSM, published in 2013, requires multiple motor tics and at least one vocal tic present for more than a year, first appearing before the age of 18. The tics cannot be explained by another medical condition or a substance such as cocaine. The motor and vocal tics need not occur at the same time. The WHO's ICD-11 asks for less, requiring only one motor tic and one or more vocal tics.

  Parents are usually the first to spot tics in their children. Early tics are often mistaken for allergies, asthma or vision problems, so pediatricians, allergists and ophthalmologists are among the first professionals to see them. In the UK, the average delay between symptom onset and diagnosis is three years. About 20% of people with Tourette's do not realize they have tics. Delays also happen because professionals wrongly assume the condition is rare, always includes coprolalia, or must be severely impairing.

  Other movement disorders can look similar. Choreas, dystonias, myoclonus and dyskinesias are more rhythmic than tics, cannot be suppressed and are not preceded by an urge. Autism-related movements start earlier, are more symmetrical and rhythmical, and involve the extremities, as in hand flapping. Depending on the case, doctors may order an EEG to look for seizures, an MRI to rule out brain abnormalities, or a thyroid-stimulating hormone test to rule out hypothyroidism. With a family history of liver disease, copper and ceruloplasmin levels can rule out Wilson's disease. For a teenager or adult with abrupt onset, a urine drug screen for stimulants may be requested.

  During the COVID-19 pandemic, several countries reported rising episodes of tic-like behavior among teenagers, predominantly girls. Researchers linked them to followers of certain TikTok or YouTube artists. These functional tic-like movements differ from classic tics in several ways. They lack the premonitory urge, cannot be suppressed, begin abruptly and do not wax and wane. There is typically no family or childhood history of tics, and the movements are "not fully stereotypical."

  Since 2008, genetic studies have suggested that Tourette's is not a single condition with one mechanism. They propose separate subtypes, distinguishing pure TS from TS accompanied by ADHD, OCD or other disorders, much as type 1 and type 2 diabetes are separated. Defining those subtypes awaits a fuller picture of the causes.

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• 7. Treatment and Daily Life

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  The American Academy of Neurology published practice guidelines for treating tics in 2019. They begin from a plain fact: there is no cure and no single most effective medication. Education, reassurance and behavioral therapy are enough for most people. Explanation alone often settles the matter. For those who are not functionally impaired, watchful waiting is an acceptable approach. Because companion conditions often hurt more than tics, they usually come first in treatment.

  Habit reversal training and exposure and response prevention are the first-line behavioral therapies. They work because the premonitory urge gives a window to practice a response that competes with the tic. Comprehensive behavioral intervention for tics grew out of habit reversal training, the best researched approach. Experts debate whether making a child more aware of tics could lead to more tics later in life. Most other behavioral methods, such as biofeedback and relaxation training, have not been systematically evaluated.

  Medication aims for the lowest dose that controls symptoms, because side effects can be more disturbing than the tics. Clonidine and guanfacine are typically tried first in children. Risperidone and aripiprazole come next, and are generally tried first in adults. Haloperidol is the most effective drug for tics but carries a higher risk of side effects. Methylphenidate treats co-occurring ADHD, and selective serotonin reuptake inhibitors manage anxiety and OCD. Deep brain stimulation remains experimental and is potentially useful in less than 3% of people.

  Up to two-thirds of parents, caregivers and people with Tourette's use dietary or alternative treatments, often without telling their physicians. None has proven benefit. Evidence is also lacking for acupuncture, transcranial magnetic stimulation, and antibiotics or plasma exchange for PANDAS.

  School and social life shape outcomes as much as tics do. Even children with mild tics can become angry, depressed or withdrawn after teasing or bullying. Some children feel empowered by presenting a peer awareness program to their classmates. Teachers who learn how tics fluctuate through the day can stop expecting a child to quit them. As one clinical passage puts it, "tic suppression can be exhausting, unpleasant, and attention-demanding and can result in a subsequent rebound bout of tics."

  Adult outcomes follow how a child was treated. They depend more on the perceived significance of having tics as a child than on the actual severity. A child who was misunderstood or punished fares worse than one raised in an understanding environment. Tics can also cause physical harm. Head and eye tics can interfere with reading, and one rare case of a cervical disc herniation was reported from a neck tic. For adults, depression adds a greater burden to quality of life than the tics themselves.

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• 8. History and Culture

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  In 1825 the French doctor Jean Marc Gaspard Itard reported what is regarded as the first case of Tourette syndrome. His patient was the Marquise de Dampierre, an important noblewoman of her time. In 1884 the influential physician Jean-Martin Charcot assigned his intern Georges Gilles de la Tourette to study movement disorders at the Salpêtrière Hospital. The goal was to define a condition distinct from hysteria and chorea. In 1885 Gilles de la Tourette published Study of a Nervous Affliction, describing nine people with a "convulsive tic disorder." Charcot then gave the condition its name.

  After those descriptions, a psychogenic view prevailed and progress stalled well into the 20th century. An epidemic of encephalitis lethargica from 1918 to 1926 hinted at an organic origin, because it was linked to a rise in tic disorders. The turning point came in 1965, when Arthur K. Shapiro, later called "the father of modern tic disorder research," treated a patient with haloperidol. He also published a paper criticizing the psychoanalytic approach. In 1975 The New York Times ran a headline linking the bizarre outbursts of Tourette's victims to a chemical disorder in the brain. Shapiro put it bluntly: "The bizarre symptoms of this illness are rivaled only by the bizarre treatments used to treat it."

  In 1994 the fourth revision of the DSM required "marked distress or significant impairment in social, occupational, or other important areas of functioning." Experts objected, because many people with Tourette's were not distressed by their tics or even aware of them. Clinicians and researchers kept using the older criteria. In 2000 the American Psychiatric Association dropped the requirement.

  Not everyone with Tourette's wants treatment or a cure. The researchers Leckman and Cohen suggest that the genetic vulnerability may carry advantages, such as heightened awareness and attention to detail. The soccer goalkeeper Tim Howard has said his neurological makeup gave him sharper perception and focus on the field. Samuel Johnson, who wrote A Dictionary of the English Language, likely had Tourette's, judging by the writings of his friend James Boswell. Speculation about Mozart has little support, since the evidence of motor tics in his life is doubtful.

  Fiction hinted at tics before Gilles de la Tourette's work. Likely examples are Mr. Pancks in Charles Dickens's Little Dorrit and Nikolai Levin in Leo Tolstoy's Anna Karenina. Modern entertainment has been criticized for depicting people with Tourette's as social misfits whose only tic is coprolalia, which deepens public misunderstanding. The 2025 film I Swear tells the true story of John Davidson, a Scottish man with severe Tourette syndrome.

  Three groups now collaborate on Tourette's genetics: the Tourette Syndrome Association International Consortium for Genetics, the Tourette International Collaborative Genetics Study, and the European Multicentre Tics in Children Studies. Tourette's research in the United States still lags behind work on autism, schizophrenia and bipolar disorder because of funding.

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