At 2pm on 26 January, Aurelia Brouwers lay down on her bed to die. Clutching a toy pink dinosaur and listening to her favourite music, the 29-year-old drank her prescribed medication as close friends gathered round. “She asked me to lie next to her. She had a smile on her face, and then she went softly into sleep,” Sjoukje Willering told the Observer. “It was very serene and calm. It was beautiful.”

Four hours earlier, Brouwers had posted her last message on Facebook. “I’m getting ready for my trip now. Thank you so much for everything. I’m no longer available from now on.” Brouwers died at home in the small Netherlands town of Deventer less than a month after being declared eligible for euthanasia under the country’s 2002 Termination of Life on Request and Assisted Suicide Act, which permits the ending of lives where there is “unbearable suffering” without hope of relief. Her death has triggered a fierce debate in a country that has one of the most permissive euthanasia laws in the world.

For not only was Brouwers young, she did not have a terminal disease such as cancer. She suffered from psychiatric illnesses, including severe anxiety, depression, eating disorders and psychosis. She self-harmed and had attempted suicide numerous times. She had spent nearly three years as an inpatient at a psychiatric hospital, and had served time in prison for arson.

Some say Brouwers’s death is a terrible illustration of the “slippery slope” inevitably associated with euthanasia legislation. Others who supported legalisation now also fear it has gone too far. Her supporters see her case as an important precedent, an escape to those in hopeless situations. “Every day was so hard. She was in a deep black hole,” said Willering. “She said it felt like a hundred knives being stabbed into her head. She never had a moment of doubt that she wanted it to end.” Her death was inevitable, one way or another, she added. “But she wanted the right to die with dignity, and she wanted other psychiatric patients to know that they also have a choice. This was her message to the world.”

This month, annual figures from the bodies that review euthanasia cases in the Netherlands showed an 8.1% increase in assisted deaths in 2017, taking the total to nearly 6,600 people. It came on top of a 10% annual increase the previous year. The vast majority had cancer, heart and arterial disease, or diseases of the nervous system, such as Parkinson’s and multiple sclerosis. But 169 had dementia, up from 141 the previous year. And 83 had severe psychiatric illnesses – up from 64 in 2016. “Supply has created demand,” said Professor Theo Boer, who supported the 2002 legislation but resigned from a regulatory body in 2014 amid concern about rising numbers. “We’re getting used to euthanasia, that is exactly what should not happen. We’re no longer speaking about the exceptional situations that the law was created for, but a gradual process towards organised death.”

The review bodies found that in 99.8% of cases, euthanasia was carried out in line with legal guidelines. However, Dutch prosecutors have recently opened criminal investigations into four cases, and last year an investigation began into a 74-year-old woman with dementia who had requested euthanasia before her illness became severe. Confused and agitated, she had to be restrained by family members to allow a lethal injection to be administered.

The focus of the current review of Brouwers’s death is a large redbrick house in The Hague, close to a clutch of museums in the north of the city. It houses the Levenseindekliniek – End of Life Clinic – a last resort for those who have been refused euthanasia elsewhere. Brouwers came here after failing to convince her own doctors and psychiatrists that she met the criteria for euthanasia. According to Steven Pleiter, the clinic’s avuncular director, a doctor and a nurse assessed Brouwers and built a relationship with her over a long period.

Her case was also reviewed by a multidisciplinary group at the clinic. “Aurelia was known to us for years. She was young but had already been suffering for a long time. Our processes are very careful,” Pleiter said.

The Levenseindekliniek has 62 doctor-nurse teams working part-time, but is on a significant recruitment drive to meet the spiralling demand for euthanasia. In 2012, the first year it was open, the clinic helped 32 people to die. Last year the figure was 750. But, Pleiter pointed out, that was only 30% of 2,500 applicants. One in every four does not meet the legal criteria, another 25% withdraw their request, and 20% die while their cases are being evaluated. Last year 9% of those undergoing euthanasia through the clinic had psychiatric illnesses and 10% had dementia. The costs are covered by the country’s health insurance system.

“Death by euthanasia is 4% of all deaths in the Netherlands. Is that a slippery slope? I don’t think so,” said Pleiter. Much of the demand was coming from the baby-boomer generation, he added. “They are thinking differently about the way life ends. God and religion are less dominant in their lives. They want more autonomy. But every case is unique.”

The decision Brouwers had waited so long for came on New Year’s Eve. It was “the best present I could have”, she wrote. “She was very happy, but she also had some hard moments, knowing she had to say goodbye to friends and family,” said Willering. “She was very open about it. You could ask her at any moment, ‘Aurelia, is this really what you want?’ and she would say, ‘Yes, I want to die.’ ” Another friend, Toon Krijthe, also at her bedside when she died, said: “I was glad for her, because I knew this was her only option – and I knew if it wasn’t a yes, she would find another way.”

Brouwers spent the days until 26 January saying goodbye to friends and working on a television documentary that was broadcast after her death. “She also visited the crematorium to plan and rehearse her funeral,” Krijthe said. “She believed in God, and she prayed, but she didn’t go to church.”

On the appointed day, two doctors from the Levenseindekliniek were present as Brouwers swallowed the liquid medication prescribed for her. “It took about 10 or 15 minutes for her to fall into sleep. She was very ready for it,” Willering said. She was cremated a week later. Within the Netherlands, it was a huge news story. As well as the television documentary, Brouwers’s death was a front-page story in the regional paper, with an additional six pages inside. “Personally I sympathise with her, and I’m happy she got a humane death,” said Boer, who teaches ethics at the Theological University of Kampen. “But culturally, I’m concerned that her death is being portrayed as a brave solution to severe suffering. She had huge support on social media.

“A border is being crossed between individual empathy and societal acceptance. If it becomes a societal norm that a person who has a psychiatric condition can opt to die, that is a problem.”

However, according to Professor Agnes van der Heide, an end-of-life expert at Erasmus University in Rotterdam, public opinion surveys show “a substantial proportion of our population think the law should be even more liberal – especially with regard to dementia”. Many who see their parents or grandparents in the grip of advanced dementia wish to opt out of such a bleak end-of-life scenario for themselves.

Not all doctors agree. Last year a group of 220 took out a newspaper advertisement saying they would refuse to euthanise patients with dementia who were unable to give verbal consent, even if the individual had signed a declaration of wishes in advance. “Our moral abhorrence at ending the life of a defenceless person is too great,” they wrote.

“It’s difficult to see how you can administer a lethal injection to a patient who doesn’t understand what you’re doing. So there is a conflict between doctors and the public,” said Van der Heide.

Facebook Twitter Pinterest The End of Life Clinic, on the face of it just another house in the north of The Hague. Photograph: Judith Jockel/The Guardian

Yet some want to go even further. Pia Dijkstra, an MP and member of the centrist-liberal D66 party, has proposed a law allowing anyone over 75, without a diagnosis of physical or mental illness, to request euthanasia. “There is a growing number of older people who want to decide themselves how their life should end – how, when and where, and in a dignified way. They feel their life has been good but it’s now complete. They want control. The existing euthanasia law doesn’t meet their needs,” she said.

A study is to be carried out before a bill goes to parliament, but Dijkstra said the proposal had the support of 60-70% of the public, with some arguing for no age restriction. “I have had an enormous number of emails and letters from elderly people who want this possibility. But it’s important to have a good debate. And it’s so important to let older people know they are valued by society, and that this should be their choice.”

It is not good for society to have organised death facilitated by the state Steven Pleiter, clinic director

Euthanasia advocates say people are helped to die regardless of the law. “About 80% of cases are reported to the review committees, which means 20% are not,” said Van der Heide. Some were in the area of so-called mercy killings, carried out by medical staff or family members; some involve palliative sedation, to relieve suffering but which ends in death. Penney Lewis, head of the Centre of Medical Law and Ethics at King’s College London, said: “Underground euthanasia happens in permissive and prohibitive jurisdictions. It happens everywhere.”

Despite the permissiveness of Dutch law, many applicants are refused, she said. “There is a lot of debate among Dutch doctors about what constitutes unbearable and hopeless suffering. But I think a model based on suffering is preferable to one based on a diagnosis.

“I’m not convinced by the ‘slippery slope’ argument. Of course, there’s evidence that the more people understand that this is an option, a greater proportion will avail themselves of it.”

The “normalisation” of euthanasia is of deep concern to Boer. “It is not good for society to have organised death facilitated by the state. A culture of euthanasia undermines our capacity to deal with suffering, and that is very bad for society.”

Not only was Aurelia Brouwers young, she did not have a terminal disease. She suffered from psychiatric illnesses

The Netherlands, Belgium and Luxembourg all have permissive laws on assisted dying and voluntary euthanasia, based on applicants’ suffering, and restricted to citizens of those countries. Switzerland allows assisted dying on compassionate grounds, and some clinics there, such as Dignitas, accept people who are not Swiss residents.

More restrictive laws exist elsewhere: assisted dying is legal in six US states (California, Colorado, Montana, Oregon, Vermont and Washington) plus Washington DC; in Canada; and in the Australian state of Victoria (after a campaign, pictured above). New Zealand is considering legislation. These are based on the “Oregon model”, which permits assisted dying for people with a terminal illness who are mentally competent and have a defined life expectancy.

In 2015, MPs in the UK voted against an assisted dying bill by 330 votes to 118. The campaign group Dignity in Dying advocates a law based on the Oregon model, covering people with less than six months to live. “Aurelia Brouwers made her choice in a very different legal context from the one we are campaigning for,” said Tom Davies of Dignity in Dying. The group is supporting Noel Conway, 68, who has motor neurone disease and has mounted a lawsuit to allow him a “peaceful and dignified death” by taking medication prescribed by a doctor. The court of appeal is expected to hear his case in May.