Mad or bad: can we tackle aggression with brain stimulation?
It could come straight out of Stanley Kubrick’s dystopian movie A Clockwork Orange: using direct brain stimulation to reduce aggressive behaviour. For PhD student Ruben Knehans, it’s his daily business. Aside from the medical complexity, it raises all sorts of questions. Is it ethical, for example, to modify someone's behaviour? Can you justify imposing brain stimulation on convicts under criminal law? How to set rules and standards? Ruben tries to answer these questions in his PhD research at UM’s Faculty of Law.
Ruben studied law and psychology and followed up with a master's degree in forensics, criminology and criminal law at Maastricht University. In his PhD research, he combines his experiences from both worlds. “This makes the research varied and therefore continuously challenging.” He is investigating whether it is possible to reduce aggressive behaviour with brain stimulation and, if so, how we can apply this in practice. This new branch in legal research is known as Neurolaw. Maastricht University is proud of this type of interdisciplinary research collaboration between faculties and of the social benefits that result from it.
From medical issue to criminal dilemma
Brain stimulation in the medical sense is not new. For years, researchers have been investigating what can be done in or around the brain to remedy diseases like Parkinson's. This disease can be treated with deep brain stimulation, in which electrodes are placed in the brain. It requires complex surgery, but the techniques are constantly being improved upon. We can now achieve positive behavioural results with electric pulses and magnetic fields outside the skull: non-invasive direct brain stimulation.
The latter technique is already being incorporated into the treatment of people with clinical depression. Magnetic brain stimulation reduces their symptoms. “These developments have made experts in other fields ask themselves whether they could also apply brain stimulation. There are increasing numbers of researchers worldwide assessing the clinical and forensic value of neuroscience instruments. We may then be able to incorporate these tools into criminal law. I am one of those researchers”, says Ruben.
This work is of great social importance. “We are always searching for ways to reduce crime and recidivism, for example, by increasing the number of police officers or cameras on the streets to deter criminals. But also through treatment programmes to ensure that criminals do not fall back into bad behaviour.”
Ruben Knehans completed the bachelor’s European Law School English Track at Maastricht University. He followed up with the bachelor’s programme Psychology and the master’s Forensics, Criminology and Law. Since 2021, he has been conducting PhD research on non-invasive brain stimulation.
Brain stimulation for aggression
Brain stimulation in case of aggression works like this: “There are billions of neurons in our brains that communicate with each other via electrical signals. This enables us to talk, move and think. With non-invasive direct brain stimulation, we increase or decrease this electrical communication within the brain with instruments from the outside. Then we monitor what happens. This work is very meticulous: half a centimetre off can mean different results.” Aggressive behaviour is mainly associated with neural activity in the frontal and top parts of the brain. “If we want to change this behaviour, we have to modify electrical signals in these areas.” In an article he recently published with colleagues, Ruben gives an overview of various studies into this phenomenon.
This brief explanation doesn’t do justice to the complexity of the entire process, he adds. “Each brain is different; everyone may have the same networks, but between individuals, these networks involve different groups of neurons. So, if we apply electrical signals at a certain place on the skull for one person, it can have a significantly different effect on another. So we need to discover much more about the differences in the human brain before we can roll out brain intervention. For example, what positive and negative long-term effects are there? Can we design a protocol, so that people don´t have to come in weekly for a new round of stimulation?”
Each brain is different. So, if we apply electrical signals at a certain place on the skull for one person, it can have a significantly different effect on another.
Then there is the ethical side of the matter. “We know that aggressive criminals, on average, show lower activity in the frontal and top parts of the brain. That is where aggressive behaviour is regulated. But can we then simply state that criminals have a different brain?” The PhD student argues that this may quickly escalate into scary and strange lines of thought. “A sharp distinction between abnormal and normal is dangerous. How do you know if someone is aggressive to such a degree that you may justify modifying their brain activity? When are we taking things too far? And doesn’t that turn criminals into objects instead of autonomous people?”
Non-criminals can exhibit similar brain activity patterns as aggressive criminals, so we know that other factors also play a role in fuelling aggression. These human rights issues are subject to much debate. “Just imagine how degrading it must be for people when we say: you are not normal, we are going to change your brain, especially when it's not just the brain that causes someone to behave aggressively. We must keep a close eye on how we balance biological and environmental factors. Our personal convictions also play a role: is our desire for collective security more important than an individual's autonomy?”
Is our desire for collective security more important than an individual's autonomy?
Capacity or identity?
Another important question to answer is what exactly do you change when it comes to brain stimulation? When you modify someone's behaviour, do you change their identity? “We try to make a clear distinction: what is called the 'mad or bad' discussion. If someone is just ‘mad’ and unable to control their behaviour, you could argue that it’s okay to help them restore their ability for self-control, even if it’s against their will. Brain stimulation might help them come to their senses and then decide what kind of behaviour they want to display”, Ruben explains. “You could draw a comparison with addiction treatment, where you ‘restore’ someone, in order for them to make their own choices without the influence of drugs clouding their judgement.”
If someone is just ‘mad’ and unable to control their behaviour, you could argue that it’s okay to help them restore their ability for self-control.
“But if someone is ‘bad’, deliberately aggressive because it fits someone’s norms and values, then it’s a different story. Forcibly changing someone’s norms and values clashes with the value that we place on individuality and autonomy. So, maybe, we should just accept that this is how someone thinks, as long as they don't hurt others.”
In his PhD research, Ruben is constantly looking for the right balance. It is a process of weighing, reconsidering and taking a different perspective.
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