by D. F. Swaab
FIGURE 19. Narcolepsy is a sleep disorder that causes excessive sleepiness during the day but fragmented sleep at night. When overcome by certain emotions, such as laughter or fright, narcolepsy patients can suddenly lose muscle tension in their arms and legs and collapse on the ground. They aren’t unconscious, even though this may appear to be the case (see photos above). This is known as “cataplexy” and results from the lack of a chemical messenger (hypocretin or orexin) from the hypothalamus. Narcolepsy with cataplexy can also arise if the brain ceases to be receptive to hypocretin. The bottom row of photos shows a large Doberman pinscher in ecstasies of excitement at the prospect of being given a tin of his favorite meat. His back legs collapse, followed by his front legs, and he then seems to fall asleep on his side, having cataplexy for a couple of minutes. S. Overeem et al., Lancet Neurol. 1 (2002): 437–44.
FITS OF LAUGHTER WITHOUT EMOTION
A reverend gentleman brought his wife to this city to seek the advice of Messieurs Le Grand, Duret, and myself [physicians], hoping that we could ascertain why she cried and laughed for no cause, but none could cure her. We physicked her in many different ways, but with very little success. In the end he took her away in the same condition in which she had arrived.
Ambroise Paré
In 1996 I was invited to take up the Emil Kräpelin guest lectureship at the Max Planck Institute of Psychiatry in Munich, a renowned institution that combines research and treatment in an excellent way. Trainee psychiatrists spend the mornings in the polyclinic and the afternoons in the laboratory. The institute’s research happened to focus on depression, one of the main strands of my own research at the time. My team had carried out a great many studies of postmortem brain tissue of depressive patients and had shown that their stress axes were hyperactive, potentially laying the foundations for symptoms of depression (see earlier in this chapter). Blood tests of depressive patients carried out by the Max Planck Institute also showed stress axis hyperactivity. So the invitation to take up the guest lectureship should have been most welcome, tying in perfectly with my research while at the same time being a great honor. Yet I felt extremely ambivalent about it. This was because the institute had been prominent in the field of eugenics during the Nazi era, euthanizing psychiatric patients and the mentally handicapped. During the Second World War, over 220,000 patients with schizophrenia were sterilized or murdered. It’s thought that three out of four psychiatric patients then living in Germany were put to death. Some sources even estimate that they were virtually all killed.
I visited my father and explained my dilemma: on the one hand an extremely attractive invitation, on the other an institute with a deeply tainted Nazi past. He considered the question for about two seconds and then said, “You must go and tell them that we are still here.” So that’s what I did. Talking about the German occupation of the Netherlands, the Holocaust, and the institute’s past proved much less difficult than I’d feared. The director, Florian Holsboer, was Swiss, the heads of the working groups represented a mix of nationalities, and the organization’s working language was English. Moreover, the German members of the staff were themselves very much preoccupied with the institute’s past. The cellar contained the records of all the murdered patients, neatly archived with German precision, and they were used for academic publications on the institute’s terrible history.
After my lecture I met a woman at the polyclinic who had a habit of bursting into stereotypically shrill laughing fits several times a day for no reason. What made it so chilling was that the emotions associated with laughter were completely absent. While knowing that you shouldn’t leap to the conclusion that someone is suffering from an extremely rare condition, I couldn’t suppress the cautious suggestion that this might be a case of hypothalamic hamartoma. Not long before, I had by chance encountered a growth of this kind in a hypothalamus, and I’d read up on the subject. The patient in Amsterdam had displayed no symptoms, and I’d never yet seen someone in real life who went about bursting into laughter because of a rare little lump in their hypothalamus. But just such a lump turned out to be visible on her scan, right at the back of the hypothalamus, near the mammillary bodies (fig. 18). The lump doesn’t grow; it isn’t a tumor but a developmental defect. It consists of clumps of nerve cells that failed to find their proper place in the hypothalamus at an early stage of development. In 50 percent of cases, the lump causes epileptic activity, provoking attacks of laughter. These are known as gelastic seizures (from the Greek gelos, meaning “laugh”). Some patients alternate between laughing and crying. The local epileptic activity can spark classic epileptic fits with seizures and loss of consciousness. Although the symptoms produced by a hamartoma have led to the hypothesis that there’s a “laughter center” at the back of the hypothalamus, it’s more likely that the location of the lump activates various brain circuits that cause the abnormal behavior.
The hamartoma can produce all kinds of hormones and can even induce puberty much too early. It can also cause psychiatric problems in children, such as ADHD, antisocial behavior, and intellectual deterioration. The cognitive malfunctions are probably due to damage to the mammillary bodies, which play a crucial role in memory (see chapter 14). Hamartomas can also be responsible for obesity and anger attacks. Abnormal hormone production resulting from these growths can be treated with medication, but the lumps can also be surgically removed or irradiated to cure patients with epileptic activity or abnormal behavior.
In investigating cases of spontaneous laughing fits, however, it’s important first to rule out other possible causes, such as enlarged pituitary glands and other tumors, MS, and various developmental malfunctions in the brain.
It doesn’t often happen that a researcher like me is able to correctly diagnose a rare condition in practice. After the event I caught myself smiling discreetly—a smile that was accompanied by all the appropriate emotions.
ANOREXIA NERVOSA IS A DISEASE OF THE BRAIN
The exact nature of this illness hasn’t been established, but it must be situated in the hypothalamus.
The French parliament recently considered draft legislation that made the promotion of anorexia a crime punishable by a maximum sentence of three years’ imprisonment and a €50,000 fine. The bill in question didn’t just target the skeletally thin models in the fashion world but also the “pro-ana” (pro-anorexia) websites that a French minister claimed were disseminating “messages of death.” The French fashion sector signed a charter pledging to promote healthy body images and to stop using ultra-skinny models. The British doctors’ association also established a link between abnormally thin models and the onset of eating disorders. And in the Netherlands, there were newspaper reports of a sixteen-year-old girl with anorexia weighing only forty-six pounds who had been expelled from secondary school. People suddenly seemed to buy into the myth that you catch anorexia by seeing it, similar to the way that homosexuality was previously regarded—completely erroneously of course—as a contagious condition (see chapter 3). In neither homosexuality nor anorexia is this view supported by any evidence whatsoever. A British public information campaign costing millions turned out to be a complete waste of money. And that was to be expected, because although an eating disorder can lead to your getting a job as a stick-thin model, no one has ever proved that anorexic models cause a spate of eating disorders.
The absence of a copycat factor in anorexia is demonstrated in the case of a woman who had been blind from the age of nine months who developed a classic form of anorexia nervosa at the age of eighteen. And contrary to popular assumption, there’s actually no evidence that anorexia is on the increase. More women, however, are coming clean about their eating disorders following similar confessions from prominent individuals like Princess Diana, the Swedish crown princess Victoria, Jane Fonda, and many other celebrities.
No one denies that anorexia is a dangerous disease. Indeed, in around 5 percent of cases it proves fatal. Some 93 percent of patients are women, suggesting that you h
ave a higher risk of anorexia if your brain has differentiated along female lines (see chapter 3). In Sweden, a cognitive therapy has been developed to teach anorexia patients to regain eating skills; it’s known as the Mandometer Method. Of course, the therapy doesn’t explain how anorexia is triggered.
All of the symptoms indicate that it is a disease of the hypothalamus. Besides the eating disorder and the loss of weight, symptoms include the cessation of menstruation, lower sex hormone levels, reduced libido, impaired functioning of the thyroid, hyperactive adrenal glands, and malfunctions in the water balance and day-night rhythms. Women who lose a great deal of weight stop menstruating. This is a protective mechanism with a huge evolutionary advantage: Women who don’t have sufficient food for themselves certainly shouldn’t become pregnant. But in 20 percent of the women who develop an eating disorder, menstruation stops before weight loss occurs. This is an indication of a primary pathological process in the hypothalamus. Some of the symptoms, like the malfunctions in the thyroid and adrenal glands, remain even after the weight has been regained. An extreme preoccupation with calories, precise food selection, and every other aspect of the eating process can persist long after someone has regained their normal weight. Take one patient who, having recovered from acute anorexia, became employed as a recipe writer for a women’s magazine. These persistent symptoms also show that a pathological process is at work in the brain and that anorexia symptoms aren’t just due to weight loss. Even when anorexia patients start to eat normally, it’s debatable, in the case of a great many of them, whether the condition has really disappeared.
The final argument for locating the disease in the hypothalamus is that all of the symptoms of anorexia nervosa can also be caused by a cyst, a small tumor, or some other abnormal process in the hypothalamus. Indeed, autopsies on anorexia patients sometimes reveal lesions in the hypothalamus. There is also the case of a patient who had been undergoing long-term psychiatric treatment for anorexia nervosa and eventually developed other neurological symptoms. Tests revealed a tumor in her hypothalamus. Of course, these comparatively rare findings don’t indicate that all anorexia patients have tumors of the hypothalamus, but they do show that a primary pathological process in the hypothalamus can cause all of the symptoms of anorexia and could explain the disease entirely. Indeed, if an MRI scan is carried out in a late stage of anorexia nervosa, the brain is seen to have shrunk, and a wide range of behavioral and cognitive disorders can be expected to result.
We haven’t yet established the exact nature of anorexia. However, it’s clear that in addition to being more common among women, there are also genetic factors that predispose a person to the disease. A number of the genes in question have already been identified. An extremely stressful life event can appear to be the direct cause of anorexia, but the factors that make someone vulnerable to the disease in the first place come into play at a much earlier stage, probably as far back as during the development of the brain before birth. It seems likely that anorexia sufferers maintain the process of voluntary starvation because they become addicted to the diet-triggered opiates released by their brains, which activate the reward center at the base of the striatum (fig. 16). But the origins of the condition remain a mystery. I favor the theory that anorexia is the result of an autoimmune process. Antibodies are indeed found in the blood of anorexia patients, directed against chemical messengers in the hypothalamus involved in regulating eating and metabolism. The only way to find out more about the condition is to carry out microscope studies on the brains of patients who have died of anorexia. But the prospect of the necessary autopsy meets with a great deal of resistance among those treating the disease as well as among patients and ex-patients. An ex-patient firmly concluded that anorexia couldn’t possibly be an illness of the brain, as she was now cured. I must confess that I never quite followed her reasoning. Fortunately, many diseases simply disappear. Another patient also dismissed the notion of a disease of the brain, because it was all about “your attitude to life”—as if that had nothing to do with your brain.
6
Addictive Substances
CANNABIS AND PSYCHOSES
Cannabis has lost its innocence.
Addictive substances have been around throughout humankind’s history, but every society and every group has different views on which are permissible and which are beyond the pale. I remember how amazed I was in the 1960s when people would stand with a glass of wine in one hand and a cigarette in the other, complaining loudly about the pot-smoking habits of long-haired layabouts. Addictive substances affect the brain by mimicking its own chemical messengers. Brain cells themselves produce a whole range of opiates and cannabinoids. The nicotine in a cigarette has the same effect as the chemical messenger acetylcholine. Addictive substances also affect the availability or the action of natural chemical messengers. The drug ecstasy, for instance, increases levels of serotonin, oxytocin, and vasopressin. That’s why your brain no longer functions optimally when you stop taking a particular addictive substance: You feel terrible and get frequent uncontrollable urges to take more of it. All such substances have a direct or indirect effect on the brain’s dopamine reward system (fig. 16), whether or not via an opiate system. Both systems are crucial to the rewarding effect of many normal stimuli, including that of sexual behavior. Not for nothing is the brief euphoria following an injection of opiates often described in sexual terms; after all, it activates the same reward system.
Cannabis has been used for recreational, religious, and medical purposes since time immemorial. The medicinal effects of marijuana were first described in China around five thousand years ago. Nor is its medicinal use in the West new. It is said that Queen Victoria used it as a remedy for menstrual pain. Cannabis has recently been rehabilitated, and medicines with its active ingredient Δ9-tetrahydrocannabinol (THC) can be obtained in the Netherlands with a prescription. Studies are being carried out on its potential efficacy against pain, fearfulness, sleep disorders, the nausea caused by chemotherapy, and glaucoma (because it reduces eye pressure). Marijuana is also thought to reduce spasticity among patients with MS, although a controlled experiment with THC couldn’t confirm such an effect.
Cannabis affects the brain because brain cells themselves produce cannabis-like neurotransmitters. The first such compound to be identified was christened anandamide, ananda being Sanskrit for “bliss.” The proteins that transmit anandamide’s message to the brain, the receptors, are mainly located in the striatum (hence the blissful feeling) and in the cerebellum (hence the unsteady gait after taking marijuana), in the cerebral cortex (hence the problems with association, the fragmented thoughts and confusion), and in the hippocampus (hence the memory impairment). But there are no receptors in the brain stem areas that regulate blood pressure and breathing. That’s why it’s impossible to take an overdose of cannabis, as opposed to opiates.
The quality of cannabis in the Netherlands has improved so much over the years that it’s rapidly changing from a soft drug into a hard drug. Daan Brühl was a nineteen-year-old boy from Amsterdam who was a champion rower. Returning from a disappointing tournament, he was seized by heart palpitations. To calm down he smoked a couple of joints with his girlfriend. Suddenly his expression altered. He walked to the kitchen, grabbed a knife, and stabbed himself in the heart. He died that evening. Suzanne, a twenty-year-old, became psychotic after smoking large amounts of cannabis. She began to hallucinate and in an extremely fearful state was taken to the hospital, where she was diagnosed with schizophrenia. Schizophrenia is a developmental brain disorder that begins in the womb (see chapter 10). However, the first psychosis doesn’t usually occur until around the age of sixteen to twenty because the sex hormones that circulate after the onset of puberty place an enormous burden on the adolescent brain and can bring on the symptoms of schizophrenia. The same applies to cannabis. It’s quite possible that teenagers who are admitted to the hospital with symptoms of schizophrenia after smoking cannabis would have suffered a psych
osis a few months later anyway. On the other hand, studies show that cannabis users are twice as likely to develop schizophrenia. Patients who already have schizophrenia but are past the worst stage can suffer from a relapse if they use cannabis. The link between cannabis use and psychosis is all the more interesting in the light of the recent discovery that the brain’s own cannabis system is activated in schizophrenic patients. Research is now being carried out to find out whether this system could be a new target for schizophrenia medication.