We Are Our Brains
Page 19
A fetus’s surroundings also affect its later propensity for aggression. Tests establishing fitness for medical service showed that men who had been severely malnourished in the womb during the Dutch famine in the winter of 1944–1945 were two and a half times more likely to have an antisocial personality disorder (see chapter 2). Malnourishment in the womb still occurs, even in our affluent society, when a placenta malfunctions. A combination of genetic factors and a mother’s smoking during pregnancy can increase a child’s risk of ADHD by a factor of nine, and ADHD is associated with greater aggression and a greater likelihood of delinquency (see chapter 2).
It’s not just our level of aggression that’s largely determined before birth. This isn’t a new idea, simply one that was regarded as taboo when faith in social engineering was at its highest. Charles Darwin (1809–1882) came to the same conclusion in his autobiography, writing that he was “inclined to agree with Francis Dalton [his cousin] that education and environment produce only a small effect on the mind of anyone, and that most of our qualities are innate.” That puts the potential influence of parents and a host of well-meaning social organizations in the right perspective (see later in this chapter).
YOUNG AND AGGRESSIVE
The Ministry of Justice is now looking beyond social factors as determinants of aggression and crime.
We’re born with different propensities for aggressive behavior depending on our gender, our genetic background, the amount of nourishment we received from the placenta, and our mother’s consumption of nicotine, alcohol, and medication during pregnancy. The likelihood of our displaying uninhibited, antisocial, aggressive, or delinquent behavior increases in puberty as testosterone levels rise. And there are considerable gender-based differences in such behavior. Men are five times more likely than women to commit a murder. Moreover, men murder a relative or acquaintance only in 20 percent of cases, as opposed to 60 percent of cases for women. The age at which men commit murders follows a stereotypical curve. As testosterone levels rise during puberty, so too does the incidence of murder. This peaks around twenty to twenty-four years, then declines to low values around fifty to fifty-four years. An identical age pattern for murders has been found in very different parts of the globe, from the United States to England, Wales, and Canada. The decline in criminal behavior among people in their late twenties doesn’t mirror declining testosterone levels but is attributed to the late development of the prefrontal cortex (fig. 15), which restrains impulsiveness and promotes moral behavior. A logical consequence would be to apply adult criminal law only when this brain structure is mature, around the age of twenty-three to twenty-five. However, politicians take no account of this development pattern, preferring to drum up votes from a fearful electorate by urging just the opposite—that is, lowering the age of criminal responsibility. The functioning of the prefrontal cortex is inhibited by alcohol, which can lead to sudden, mindless violence after a night out. Damage to the prefrontal cortex in the first years of life can also disrupt social and moral behavior later in life.
Testosterone stimulates aggression. Some men have higher testosterone levels than others and are therefore more likely to become aggressive. Men imprisoned for rape and other violent offenses have been found to have higher levels of testosterone than other types of offenders, and these levels are higher in prisoners in general and in military recruits with antisocial behavioral tendencies than in the rest of the population. The same link between higher testosterone levels and greater aggression applies to female prisoners too, by the way. The aggression shown by hockey players during games can easily be measured by the incidence of blows with sticks. Here, too, a link has been found between aggression and blood testosterone levels. So it’s worrying that such huge amounts of anabolic steroids are currently taken in the world of sports to increase muscle mass, because this hormone also increases aggression.
Environmental factors play a role, too. Violent films and computer games have recently been shown to heighten aggression. Interestingly, the same effect is produced by reading biblical passages in which God sanctions killing (but only in people who are religious). What’s more, physical factors like temperature and light greatly affect our actions. Everyone knows that long, hot summers can spark violent incidents. The influential factor in decisions to go to war turns out not to be military strategy but the amount of daylight and the temperature. This emerged from Gabriel Schreiber’s study of 2,131 conflicts in the last 3,500 years, which found a pattern of annual rhythms. For centuries, the decision to declare war has largely been made in the summer in both the northern and southern hemispheres, while season didn’t play a role in equatorial regions.
Factors such as a deprived background and lack of education have of course long been known to contribute to aggression and delinquent behavior. Indeed, these are the only factors to have been researched in previous generations. When the Italian criminologist Cesare Lombroso (1835–1909) was accused of paying too little attention to the social causes of crime, he answered that this had already been done by countless academics, adding that it was “pointless to prove that the sun shines.” Until recently, the Dutch Ministry of Justice also focused only on the social causes of crime, but it’s now showing interest in other factors that increase levels of aggression and the likelihood of criminality.
AGGRESSION, BRAIN DISORDERS, AND PRISON
How often does our criminal justice system violate the principle that penal law shouldn’t apply to people with a brain disease?
Rules on criminal liability have been in place ever since Daniel M’Naghten killed the British prime minister’s secretary in 1843 and—to the general shock of Victorian England—wasn’t jailed but put in a lunatic asylum. Under the “M’Naghten rules,” as they came to be known, criminals with mental disorders could be judged “guilty but insane” and placed in a secure hospital facility rather than sent to prison. Yet although we agree that such individuals can’t be held criminally liable, prisons today are full of people with psychiatric or neurological diseases. According to the Dutch forensic psychiatrist Theo Doreleijers, 90 percent of young people in prison have a psychiatric disorder, and 30 percent of individuals detained under hospital orders have ADHD.
In the case of brain disorders associated with aggressive behavior, two areas of the brain working together are of special significance: the prefrontal cortex (fig. 15) and the amygdala (fig. 26). The front of the brain, the prefrontal cortex (PFC), inhibits aggressive behavior and is crucial for moral judgments. Children whose PFC has been damaged often have difficulty learning moral and social rules. Vietnam veterans with damage to the prefrontal cortex became more aggressive and violent, and impulsive murderers also show reduced activity in their PFC. Brain disorders that affect the PFC tend to be associated with aggressive behavior. A surgeon who carved his name in a patient’s abdomen at the end of an operation turned out to be suffering from Pick’s disease, a form of dementia that starts in the PFC. Schizophrenia, also marked by reduced activity in the PFC, can lead to aggressive behavior. John Hinckley Jr. gained notoriety after his attempt to assassinate President Reagan. (The bullet from his pistol hit Reagan under the left armpit and bored through his left lung but stopped an inch from his heart.) Hinckley’s brain scan, which went around the whole world, clearly showed the shrinking of the brain that’s typical of schizophrenia. He’s still in prison. In 2003, another schizophrenic patient, Mijailo Mijailović, murdered the Swedish foreign minister, Anna Lindh, after he stopped taking his medication. He believed that Jesus had chosen him for this purpose and heard voices telling him to commit the murder. Conversely, aggressive behavior can sometimes be the first symptom of schizophrenia.
The amygdala (fig. 26), an almond-sized structure, is located deep within the temporal lobe. When you hold the gelatinous mass of a brain in your hands during an autopsy, you can feel, within the pole of the temporal lobe, the solid little button of the amygdala. Stimulation of the amygdala inhibits or induces aggressive behavior, dep
ending where and how it’s done. Its inhibitory effect was convincingly demonstrated by the Spanish physiologist José Manuel Rodriguez Delgado, who was able to stop a bull in mid-charge through the remote electrical stimulation of its amygdala. If you disable this structure on both sides, even sewer rats will become tame. Some psychopaths have a malfunction of the amygdala. This prevents them from seeing from their victims’ facial expressions that they are suffering and thus from feeling empathy toward them. In 1966, Charles Whitman killed his wife and mother and then went on to shoot fourteen people dead and wound thirty-one others at the University of Texas in Austin. He was found to have a tumor of the temporal lobe, which was pressing on the amygdala. It makes you wonder how many other people who go on shooting sprees in schools or elsewhere have a brain disorder. Ulrike Meinhof started her career as a critical journalist, later becoming one of the founders of the Rote Armee Fraktion in Germany, a terrorist group that killed thirty-four people. Meinhof committed suicide in her cell in 1976. Doctors had previously discovered that she had an aneurysm, a bulge in the wall of a blood vessel at the base of the brain that was pressing right on the amygdala. This caused lasting damage. When she was operated on for the aneurysm, the neurosurgeon also damaged the prefrontal cortex, so there were two possible causes for her aggressive and lawless behavior.
Other brain disorders that are sometimes linked with aggression are mood disorders, borderline personality disorder, learning disabilities, brain infarcts, MS, Parkinson’s disease, and Huntington’s disease. Even patients with dementia can be aggressive. In 2003, an eighty-one-year-old Dutch woman who’d been placed in a nursing home because of her dementia murdered her eighty-year-old roommate. She was found on the toilet in a confused state, and it was only when a nurse took her back to bed that the victim was spotted. Fortunately, the Public Prosecution Service decided not to prosecute. In “civilized” countries like the United States and Japan, schizophrenic patients who have committed a murder can still be given a death sentence. I hope that will never happen again in the Netherlands. But how often does our criminal justice system violate the M’Naghten rules?
GUILT AND PUNISHMENT
The criminal justice authorities should learn from the medical world how to adopt an evidence-based approach founded on properly controlled studies.
Criminal law can only be applied to people with a healthy brain. This principle also has a biological foundation. Rhesus monkeys normally punish any animal that doesn’t stick to the group rules. However, the primatologist Frans de Waal observed that a mentally retarded rhesus monkey with Down syndrome was allowed to get away with breaking all of the group’s standard rules. Humans should behave similarly, but apparently we find it hard to do so.
Forensic psychiatrist Theo Doreleijers discovered thirteen years ago that 65 percent of underage delinquents brought before a public prosecutor had psychiatric disorders, but medical reports had been requested in less than half of the cases. Can we hold such children liable for their deeds? Child abusers have often themselves been abused as children, so to what extent are they culpable? How accountable is an adolescent for his actions when his brain is suddenly deluged with sex hormones that are modifying the function of almost all of its parts? A child has to learn to deal with a whole new brain during puberty, at a time when the prefrontal cortex, which inhibits impulsiveness and controls moral behavior, is extremely immature. And how accountable are addicts for their condition, which was caused by tiny variations in their DNA or malnourishment in the womb?
In other words, moral condemnation and punishment based on personal accountability rest on very shaky ground. However, our sense of morality is strongly anchored in our evolutionary development, because it affects the survival of the group. It also accounts for the idea that each individual is responsible for his or her own deeds, illusory though this is.
However, contrary to what is sometimes thought, that we’re programmed in certain ways doesn’t mean that we should do away with punishment entirely. After all, the next time we decide whether or not to do something, our brains can factor an effective punishment into our unconscious deliberations. And punishment also has aspects that have nothing to do with personal accountability. Society requires criminals to atone for their deeds; it also wants them to be locked up for its protection and as a warning to others—though the effectiveness of this latter aspect is debatable.
The knowledge that we possess about the neurobiological risk factors for aggressive or criminal behavior always relates to a group of individuals with a certain characteristic. As a result, we can’t assure a court that a particular factor has contributed to a particular individual committing a crime. Some therefore claim that the practical contribution of neurobiological knowledge to sentencing or detention on remand is of marginal importance. Ybo Buruma, a member of the Dutch Supreme Court, rightly said in an interview in the newspaper NRC Handelsblad (November 7, 2000), “Courts, like doctors, deal with individuals.” But he went on to draw exactly the wrong conclusion: “I think all this knowledge is terrific, but as long as we can’t apply it on an individual level in court cases, it’s of no use to us.” Thus he reduced law as a science to the level of medicine a hundred years ago, when doctors also treated their patients on an individual basis to the best of their ability but had no idea what the effect would be. Medicine has learned its lesson; evidence-based medicine is always founded on the effects on a well-defined group of patients. You never know whether the one patient you prescribe medicine for will belong to the 95 percent who are cured as a result or the 5 percent who will experience serious side effects and, very occasionally, die. Yet you make the decision to treat that one patient on the basis of good data. And this is how we should look at the factors that determine aggressive and criminal behavior in a particular group and the way in which this group responds to preventive measures and different types and degrees of punishment. Only on the basis of such data can we make pronouncements about an individual that are based on probability, in the knowledge that our judgment regarding that person can’t be entirely certain but will at least be correct with respect to the group to which he belongs. Alas, the criminal justice authorities have a very long way to go in this regard. They keep trying out new forms of punishment, from community sentencing to boot camps for young criminals, without a proper control group, which means that the effectiveness of a given punishment will always be controversial.
VIOLENT WHILE ASLEEP
There is, in all of us, even in good people, a lawless wild beast that emerges when we sleep.
Plato, The Republic, 380 B.C.
Dream sleep coincides with darting movements of the eyes, which is why it’s also known as REM (rapid eye movement) sleep. It’s also referred to as “paradoxical sleep” because EEG scans reveal that the brain is extremely active at this time. This combination of brain activity and rapid eye movement was discovered by Eugene Aserinsky in 1952, when he monitored his small son during REM sleep.
During dream sleep we exhibit many of the characteristics of psychiatric and neurological disorders. Our higher visual centers are activated, and we hallucinate like patients with schizophrenia. We experience incredibly bizarre events in a world in which the laws of physics and of everyday society no longer apply. Dreams often carry an emotional or aggressive charge; not surprisingly, the amygdala (fig. 26), the center of aggressive behavior, is activated at these times. When we dream we make up stories, just as people with alcohol dementia fill up the holes in their memories with stories about events that never took place (see chapter 10). A few minutes later we forget everything that we experienced in our dreams, as if we were suffering from a severe form of dementia. During dreams we lose muscle tension, just as narcolepsy sufferers with cataplexy do while awake.
It’s not for nothing that we lose muscle tension while we sleep. Retaining it can lead to activity during sleep; sleepwalkers, for instance, are deeply asleep, but they have normal muscle tension. They can perform automatic, semi-purposeful a
ctions, of which walking is an example. They are unaware of what they do and are afterward unable to remember any of their actions. (A scan of a sleepwalking patient indeed showed that large parts of the cerebral cortex aren’t activated during sleep.) The French scientist Michel Jouvet carried out experiments on animals in which he created slight lesions in the brain stem, destroying the nerve cells that make the muscles relax during sleep. The animals in the study were shown to carry out the actions that they were dreaming about. He saw a cat in dream sleep leap on its imaginary prey with open eyes, without having the least awareness of her surroundings. She wasn’t at all interested in a bowl of tempting cat food, nor did she purposefully remove the mess that was placed on her coat, though she did automatically clean her coat while asleep. Rats with lesions of this kind played with invisible rats during their dreams, and squirrels dug up nuts.
Humans, too, sometimes perform complicated actions during dream sleep of the type witnessed in the above animal study. They also occasionally become aggressive. One woman told me:
Three years ago my husband was suffering from nervous tension. One night he made such strange noises in his sleep that he woke me up. I tried to calm him by stroking his head. That turned out to be a bad idea, because he grabbed me by the throat and tried to throttle me. Since I was by now wide awake I was able to free myself and to wake my husband. When I told him what had happened he was dreadfully shocked, so much so that he hardly dared go back to sleep. He told me that he’d dreamed he was being attacked and that he’d tried to defend himself. This dream recurred a few times. Each time I was woken up by the sounds he was making. I made sure to put some distance between us before stroking him softly so that he calmed down again. We discussed these events with our children and with friends, and wondered what would have happened if I hadn’t been able to free myself. Would he have gone to jail?