Lin Zhang carefully places two microscope slides next to each other on the table in the lab of the Netherlands Brain Institute. It is no longer evident that the wafer-thin preparations between the glass once belonged to a human brain. One of the samples is barely visible at all: the piece of brain cut so immeasurably thin that it has become almost transparent.
“This one comes from someone who died of natural causes,” says Zhang. ‘Even with the naked eye you can clearly see the difference with the other preparation: this one is light, the other dark.’
With nimble fingers, Zhang places the two slides one by one under the microscope. First the light, then the dark. ‘Are you watching?’
In the round field of view of the lens, almond-shaped contours appear against a dark gray background, like that of a noisy television. “This sample comes from someone who died through legal euthanasia,” says Zhang, as if retelling a suspenseful movie. ‘Do you see those dark structures around the neurons? We call these perineuronal nets. There is extremely strong discoloration here, which means that the cells were very active at the time of death.’
Suicide detectable in the brain
In other words, Zhang discovered that suicidality is detectable in the human brain. A breakthrough, because it makes it more likely that a drug can be found in the future that cures suicidality.
‘Every year, more than 700,000 people die from suicide worldwide,’ says the PhD candidate. ‘Most people still believe that psychiatric disorders and somatic diseases [lichamelijke aandoeningen, red.] are fundamentally different from each other. If we are cut by a knife, we get a scar. The diagnosis is then clear: there is an injury. This is now the first time that we have been able to determine that something similar happens during suicide: that measurable neurobiological changes take place in the brain. Suicidal thoughts change our brains – and the damage seems permanent.”
Suicidality is not a symptom of depression
Furthermore, Zhang’s discovery may explain why antidepressants do not always alleviate suicidal thoughts, and sometimes even make them worse.
‘Ninety percent of people who commit suicide have underlying psychological suffering, such as depression. This is not the case with the other ten percent. Science generally assumes that suicide is a symptom of depression. We found that the two produce different neurobiological changes that occur in separate brain regions. They are separate from each other.’
Taboo on suicide
With care, Zhang places the two slides back into a wooden sorting tray, carefully maneuvering each piece of brain between her fingers, as if acutely aware of the life that preceded her research. Before Zhang joined the research group of physician and neurobiologist Dick Swaab six years ago, she was a forensic pathologist in China.
‘Suicide is still a major taboo in many developing countries,’ says the PhD candidate seriously. ‘Some families experience it as a humiliation and destroy the evidence. As a pathologist, I have often thought: what if there was a biomarker with which we could diagnose suicide with certainty? And now it is here.’
Zhang received his PhD at the end of October in the Aula of the University of Amsterdam, and some of her research has already been published. “After my presentation, a lady came up to me to congratulate me,” says Zhang. ‘I didn’t recognize her. She took my hand and said her daughter had committed suicide. She was only fourteen.’
Zhang sighs deeply. “It would be naive to say that I want suicide to never happen again,” she says. ‘But I do hope that with my research I can drastically reduce the number of suicides.’
Editor
Merav Pront is a digital editor at National Geographic and also regularly writes for the magazine. During her studies in human geography, she learned to place local phenomena in an international context. As a freelance journalist, she looks for the small stories behind the big news. She writes for the VPRO and the National Holocaust Museum, among others.
2023-11-07 17:58:08
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