by Emma Byrne
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Although there’s been plenty written about the range of different urges that TS patients experience, it hasn’t got us very far in understanding why some people experience these debilitating and hard-to-control compulsions. While on the surface, the urge to shout “motherfucker” in a library might seem a million miles away from the urge to blink or gesture, there is probably a common underlying cause. Whereas TS was once thought to be a psychiatric condition, we now know it’s more likely to be, primarily at least, a movement disorder. All of the tics that TS sufferers experience might come from an inability to suppress unwanted, involuntary movements, even those that are as complex as those needed to say (or sign) a swear word.
That raises a further question: why do TS sufferers find it so difficult to suppress these troublesome urges? Most of us have felt the impulse to do something totally inappropriate at one time or another, like shout “fire” in a crowded theater or touch a flame, but most of us can move past those urges without acting on them. Not so for TS sufferers, or at least not without a great deal of stress and anxiety. Once these urges begin, only performing the action gives relief.
What is so different about the brains of TS sufferers? The answer, unfortunately, is that we still don’t precisely know, partly because the syndrome is so variable. As well as the diversity of different types of tic, people with TS process their urges in very different ways. Some find their urges harder to control than others. Some are more likely to act on their urges at times of great stress whereas others find that fear of people’s reactions motivates them to control their tics. In fact, some patients try very hard to suppress their swearing in front of their doctors, adding to the difficulty of learning about this condition.
One of the greatest challenges in properly documenting and studying TS is that it rarely strikes alone. Most young people with TS are also diagnosed with depression or anxiety disorders (hardly surprisingly) and are also very likely to have OCD or ADHD.8 What’s more, several of the characteristics of OCD overlap with those of TS. For example, one of the compulsive thoughts that characterize OCD is the urge to shout an obscenity in church, according to the fourth edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM).
We do know that TS is highly heritable: there are genetic variants that predispose children to TS, and those genetic variants are much more likely to occur in children whose family members include other TS sufferers. The exact genes haven’t been identified yet because comparing the genetic makeup of TS sufferers takes time, though there are some tantalizing hints as to which gene variants might be involved. To complicate matters, some of the genetic traits that are regularly seen in TS sufferers are also common among sufferers of OCD, which could explain why the two disorders so often go hand in hand.9
The effects of TS are hugely debilitating for some sufferers. Motor tics and other compulsions don’t just draw unwanted attention; they can often be physically destructive. Muscular spasms commonly cause broken bones, neck injuries, and concussions.10 Add to that the fact that many TS victims suffer from the compulsion to pick, pull, or otherwise damage their skin—and motor tics are quite obviously harmful. Yet for those patients who experience coprolalia, coprographia, and copropraxis, the physically injurious motor tics aren’t anywhere near as distressing as the socially inappropriate urges.
That might sound surprising: who would choose a bit of embarrassment over a concussion or broken bone? But vocal outbursts and startling gestures can cause all sorts of problems ranging from exclusion from school to becoming a target for bullying or abuse.11 The sad fact is that, for most TS sufferers, the syndrome is at its most severe in late childhood and early adolescence, at the exact time that most of us are making lasting friendships and working out who we want to be. The social stresses caused by TS lead to problems long after the syndrome itself has become less of a daily burden.
Professor Christine Conelea surveyed 970 adults who had had TS as children and found that many of them still suffered from social exclusion and other psychological difficulties, leading to a poorer quality of life: the lasting impact of TS on children’s social and educational lives is distressingly severe. Professor Conelea surveyed 270 children with the syndrome, along with their parents. Forty-three percent of the families said that they avoided social events because of tics, while 38 percent said they avoided public places altogether. That might be because three-quarters of the families surveyed said that they had experienced discrimination and 14 percent had been asked to leave a public place. As if this social stigma weren’t bad enough, TS can have a serious effect on education, with 65 percent of children saying that the disorder interfered with their ability to study and 21 percent having been asked to leave a classroom or other educational environment because of their disorder.
Dr. Ruth Wadman of the University of Nottingham has been studying the relationships between children and young people with TS and their peers without the syndrome. Here too, she has found that children with TS are likely to suffer from social isolation and embarrassment, are more likely to be bullied and withdrawn, and are more likely to be rated as less likable by the people who know them.
So much of this distress and isolation comes from a lack of knowledge about the problem. Perhaps we should be concentrating as much on developing greater understanding of the condition as looking for a cure. In the meantime, supportive therapy can help some young people feel more comfortable in their own skin. Dr. Wadman interviewed six teenagers with TS and found that they all had different coping strategies.12 Some young people try to make their tics a part of their identity, while accepting that this might make other people feel uncomfortable, essentially saying “fuck it!” to the idea of trying to fit in by suppressing their urges. For some, this is a good solution. One teenager told Dr. Wadman that he deals with his TS “extremely well.” Despite his severe symptoms and the depression that he also suffers, he’s chosen to let other people decide if they accept him or not. “I basically have decided somewhere in my head that if people can’t deal with it, it’s not my problem,” he says.
But for others it’s not easy to be so sanguine about what other people think. For example Hayden, who has moderate TS and OCD, said: “Every time I meet someone new it’s almost as if I try and be funny and make them laugh. But that’s just me covering my tics, and then everybody just thinks I’m weird from that moment on.” With more than one in two hundred children diagnosed with TS, that’s a lot of lonely and isolated young people out there.
Because of a general lack of public awareness—exacerbated by the fact that “Tourette’s” is so often the punchline to an unfunny joke about swearing—the behavior of patients with TS can seem extremely strange to those of us who aren’t familiar with the condition. As well as the unpropositional swearing and involuntary muscle movements, TS sufferers are also likely to experience other compulsions that can get them into serious trouble. Professor Madeline Frank and her colleagues at the University of Birmingham and University College London found that three-quarters of TS patients have impulse-control problems, ranging from uncontrollable bouts of anger and aggression to compulsive shopping, shoplifting, hair-pulling, and pyromania. Fewer than one in ten members of the general population and less than a third of all psychiatric in-patients suffer the same problems.
These compulsions are harmful as well as distressing. Nine out of ten of us have no problem controlling the occasional self-destructive urge, usually limited to resisting telling the boss to go fuck themselves. But as difficult as that can sometimes be, most of us have no problem suppressing those impulses when they arise. For TS sufferers, suppressing destructive urges is much more of a challenge and we aren’t yet sure why. It might be that the ability to suppress harmful impulses is somehow weaker in TS patients, which would explain why their tics are so hard to control. On the other hand, it might be that the constant effort to control their tics tires out the impulse control parts of the br
ain.
We all do this: it’s a phenomenon called the “ego depletion model of self-control” and it was first studied by Professor Roy Baumeister at the University of Florida. He set up experiments that would force people to exercise impulse control and then tested to see whether they were more or less able to suppress unwanted behavior as a result. In one instance he showed people a film that would make them either happy or sad, but told them to suppress their feelings. Those volunteers gave up much faster on a subsequent test of physical stamina than the other volunteers who watched the same film without trying to suppress their emotions.
He also ran an ingenious test of self-denial and our ability to persevere with difficult tasks in the face of adversity. Professor Baumeister offered volunteers a choice of chocolate or radishes as a snack when they arrived at the lab. Bizarrely enough—and to me this is the finding that really needs explaining—some of the volunteers were persuaded to choose the healthy radishes over the chocolate. He then gave all of the volunteers a frustrating (and secretly impossible) math problem and measured how long it took for them to give up. The people who had already experienced the frustration of eating radishes (radishes!) instead of chocolate gave up after less than ten minutes while the chocolate eaters carried on for nearly twenty minutes. Could this experiment simply prove that chocolate makes us happier than radishes and thus more likely to persist in adversity? Or that blood sugar levels are correlated with persistence? Possibly, but those volunteers who were offered neither chocolate nor radishes carried on for even longer than twenty minutes!
Even having to consider whether to make a self-indulgent choice causes some fatigue to our inhibitions and self-control, both of which are essential ingredients in our willingness to persevere in doing something frustrating but necessary.13 Which is why I don’t even think about dieting.
Because of the complicated but common relationship between TS and impulse control, it’s long been hypothesized that the syndrome might be an executive function disorder. Executive function is what we call our ability to switch between tasks, make plans, or use our working memories. Professor Rebecca Elliott of the University of Manchester says that executive function is a bit of a catch-all term for complex processes that coordinate the more basic workings of the brain in order to achieve higher-order goals.14
Several things can impair executive function, from fatigue to frontal lobe damage. In order to discern the links between executive function, impulse control, and TS, Professor Clare Eddy and her colleagues at the Barberry National Centre for Mental Health in Birmingham, England, asked forty patients with TS and twenty non-TS controls to take part in a series of tests of executive function. Crucially, all the volunteers with TS were otherwise healthy: they didn’t have ADHD, OCD, or other psychological or neurological problems, so she could study the effects of TS in isolation.
Executive function includes things like verbal fluency, which Professor Eddy tested by asking the volunteers to name in one minute as many words beginning with the letters F, A, or S as possible: a particularly provoking set of initial letters for English-speaking coprolalia sufferers! She also tested their working memory by having them listen to three- to eight-digit numbers and then recite them back in ascending order. So for example, if you heard 76843 you would have to reply with 34678. Finally, she tested impulse control with something called the Stroop test.
The Stroop test is a simple psychological experiment. Volunteers are shown the names of colors, printed in colored ink. For example, I might show you a card with the color “red” named on it, but printed in the color blue, or “black” printed in yellow, “green” in orange and so on. Your job would be to name the color of the ink rather than saying the name of the color written on the card. It’s surprisingly difficult, and we can quantify exactly how difficult people find this task by comparing their reaction times when the name and the ink match (“red” in red ink for example, known as a “congruent condition”) and when they don’t match (“red” in green ink, an “incongruent condition”). If the colors match, the average person can correctly name a hundred colors in sixty seconds. In contrast, for the incongruent examples it takes on average 110 seconds to name a hundred colors.15
The Stroop test allows us to probe exactly how difficult it is to inhibit an easy-but-wrong response in order to allow a difficult-but-right one to come out. The bigger the difference between the response times, the harder the brain is having to work in order to exercise its inhibition.
Professor Eddy and her team found that TS patients could generate on average forty entries on the “list words beginning with F, A, or S” task, whereas the control group generated fifty. She also found a slight difference between the number-ordering task: TS patients could manage entries up to six digits in length, on average, whereas the control group could manage almost seven digits. On the Stroop test, TS patients made one and a half as many errors (and took longer) than the control group.
Patients with uncomplicated TS found all three tests of executive function much harder than the healthy controls, but this could mean one of three things: that TS causes the executive function problems, problems with executive function cause TS symptoms, or executive function impairment and TS are two separate disorders that just happen to show up together frequently like TS and OCD. According to Professor Eddy, we still don’t know which explanation holds; TS sufferers definitely struggle more with inhibition, but no one knows why. However, it is possible for many TS sufferers to delay or divert their reaction to those urges.
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While some patients find it easier to suppress their swearing in public (where anxiety levels are high, but the social penalties for swearing are higher), others find it easier to suppress their swearing among friends and family, in settings where they are more relaxed. Stress might increase the severity of the urges that some TS patients feel, which would explain the greater severity of tics in high-stress situations. For others, the fear of social consequences acts as a very strong motivator to suppress swearing and other tics, no matter what the cost. To make sense of this, Professor Conelea set up an experiment to differentiate between situational stress and social pressure. She set TS patients time-limited mental arithmetic problems in order to induce a baseline level of stress. She told these patients that they could swear or tic as much as they wanted. When allowed to tic freely, these patients’ tic rates were slightly lower while doing the maths challenge than when they were just resting, possibly because of the amount of concentration that the mental arithmetic required. She then asked them to try again, but this time to try to suppress their tics. As a result, the number of tics per minute almost doubled under stress. The very stress of trying not to act on ticcish urges made it much more likely that the volunteers would suffer from tics.
Behavioral studies like these can tell us a lot about the environmental and psychological factors that affect patients with TS, but they still don’t tell us what’s going on inside the brain. The behavior of each and every one of us is the product of a complicated interplay between chemical and electrical signals, but we still have only a vague understanding of how these all fit together. New brain-imaging techniques and a better understanding of the complexities of TS sufferers’ behavior mean that the picture is now clearer than ever, but we still lack a complete model of what makes TS sufferers tic.
One possible reason why Tourette’s syndrome sufferers develop tics has to do with an important chemical in the brain. We believe dopamine plays an essential role in TS, mainly because the drugs that most successfully treat the disorder have an effect on the way the brain uses dopamine as a signal. Dopamine is a neurotransmitter—a chemical that neurons release in order to encourage other neurons to fire—that has a range of functions in the human brain and the body. We need dopamine to tell the kidneys to excrete urine, and to tell the pancreas not to overdo it on the insulin production.
In the brain, dopamine is yet more of a shape-shifter. Even though, of the 100 billion neurons in the br
ain, only 20,000 or so are receptive to dopamine, these 20,000 receptors have a huge influence on our behavior. We experience the action of dopamine in certain parts of the brain as a reward. When you do something difficult that pays off, the high you feel is, in part, the feeling of dopamine being released by some neurons and absorbed by others. Too much dopamine can make you psychotic, too little and you lose the motivation to try difficult things because you don’t receive the dopamine “high” you expect as a reward. Cocaine gives you an “unearned” dopamine hit, while antipsychotics stop dopamine from giving us that sense of reward at all.
The action of antipsychotics on TS gave the first indication that the brain’s reward system might somehow be involved in the syndrome. It wasn’t until 2011 that Professor Stefano Palminteri and his colleagues at the Pierre and Marie Curie University in Paris studied the effect with a clever test that examined the role of rewards in people with and without TS.16 His recruited volunteers were to carry out a test of how rapidly they could press a combination of keys when they saw a prompt on a screen. The volunteers were asked to put the fingers of one hand on the C, F, T, H, and N keys of their keyboard. This puts all five digits in a slightly awkward inverted V-shape. The screen would then flash up a prompt, telling the participants the order in which they should press the keys.
Each volunteer saw ten different sequences and each sequence was shown fifteen times over the course of the experiment. Of those ten, five would give them a maximum ten-euro reward if they pressed the keys correctly, while the other gave a maximum reward of one cent.