Six years ago, I sat halfway up a spiral staircase in an old medical library in London, watching an actor recreate one of the most intense moments of my life. We were filming a TV drama based on a memoir I’d written about my struggles with disturbing sexual and violent intrusive thoughts.

The story had started when, aged 15, I was suddenly bombarded by relentless, maddening doubts about core aspects of my identity: my capacity for violence and abuse, my physical appearance, my sexuality, whether I could trust my bones not to break. Graphic, unbearable thoughts and images started looping in my mind, thousands of times a day. I had no language for my devastating anxiety, or for my shame, so I kept it all a secret for 12 years.

The scene we were filming that day was based on the euphoric moment in my 20s when I first discovered that my thoughts were typical symptoms of obsessive-compulsive disorder (OCD), and that there were others out there battling this common enemy. “Oh my God. Oh my God. Oh my God. Fuck. It’s OCD. I’ve got OCD!” said actor Charly Clive as she read a list of symptoms from the medical textbook in her hands, giving voice to the astonishing clarity and relief that diagnosis can bring in a bewildering mental-health landscape.

Regardless of the labels I’d been given over the years (I’d previously been diagnosed with depression and anxiety), doctors had always framed it in the same way: illness. This was due to the received wisdom that mental disorders are diseases of the brain with organic, biological root causes; and to the medical language that infused charity campaigns and the media. It was also due to the ideas explicitly promoted by professionals who treated me. One of my CBT (cognitive behavioural therapy) therapists said that OCD is primarily caused by a misfiring amygdala, a structure in the temporal lobe of the brain. Another said that their trademarked therapy could “rewire my brain” in six weeks.

In 2013, I finally shared the story of my struggle with OCD in an article that became a book, Pure, that was adapted into the TV show of the same name. Soon followed invitations to write more articles, endorse charities, speak at conferences and guest on TV magazine shows. I had become the poster girl for OCD.

And I co-opted the language of medical professionals who treated me. “Mental illness can happen to any of us,” I wrote in Vice in 2014, “like a cold or a cancer.” I broadcast messages I’d been told were facts: the root cause of mental illnesses are biological abnormalities in the brain; mental illnesses are illnesses like any other.

Sitting on the staircase in that library in 2018, watching the TV show being made, should have been an affectionate look back on the pivotal diagnosis that led to my recovery. A chance to celebrate the turning-point moment when I’d first seen my secret inner reality reflected back at me. Charly wept in front of the camera while I wept behind it as we rolled another take.

But as our tale of hope was making its way to the screens of millions of people, in private I was growing more hopeless. I knew what no one else knew, that the relief of being diagnosed had been brutally short. That not only had the terrifying intrusive thoughts now returned, but I had begun to question almost everything I thought I knew about mental health.

* * *

The turning point came a few months before filming, when I visited Trinity College Dublin to interview neuroscientist Prof Claire Gillan for a mental health charity podcast. Gillan was studying feelings and behaviours across a variety of psychiatric diagnoses. I was accustomed to softball media engagements about fighting stigma, and expected more of the same. I asked what she had discovered.

“OCD is not a biological reality,” Gillan said, very matter of factly. “That’s what the data increasingly shows.”

A lump rose in my throat. I fumbled for a response. Hadn’t researchers proved that OCD brains are different biologically? (Some neuroimaging studies show increased activity in various cortices.) “Abnormalities in these regions are by no means exclusive to OCD,” Gillan said. “A great many disorders show the same kinds of brain changes.”

I didn’t know this. I thought my brain shared the same abnormalities as everyone else with OCD and that these were the root causes of our obsessions; that we had brains that were measurably different from the brains of people with, say, ADHD or anorexia. I thought this was the definition of “official” diagnosis. Gillan explained that, on the contrary, psychiatric diagnoses are not based on biomarkers, they are subjective constructs.

I felt torn with nerves for the rest of the interview. I wanted to dismiss what I’d heard, and yet felt compelled to learn more. Afterwards, I started reading, and was incredulous to discover innumerable similar assessments. Apparently, Prof Allen Frances, who literally wrote the book on diagnosis as the lead editor of the fourth edition of the Diagnostic Statistical Manual of Mental Disorders (the handbook widely used by doctors), had said psychiatric diagnosis was “bullshit”. As he told Wired magazine in 2010, “These concepts are virtually impossible to define precisely with bright lines at the boundaries.”

As I dived deeper, I encountered ideas that shook me and my message at the foundations: decades of criticism, not just of diagnosis but of the entire medical model. Evidence that exposure to environmental stress is the leading determinant of common mental health problems like anxiety, depression and OCD, seemed to be overwhelming, whereas evidence that organic brain dysfunction or genetics are the leading causes of such conditions seemed to be comparatively scant. I put down my laptop, lay down on the sofa and cried. This felt like an attack on my identity, like I was being told my suffering wasn’t serious. If my thoughts weren’t illness, did that mean they were “me”? Did I want the shit in my head? Did I choose this?

I would later come to understand that to question the medical model is not to question whether mental health problems exist: they are real and devastating. I would learn that, yes, there are brain changes that correlate with poor mental health, changes that entrench and compound distress. But that neuroscience is far from being able to understand these correlations, much less categorise them into discrete conditions, or explain why brains start to become disordered in the first place. Mental health is far more complex and mysterious than any doctor had ever admitted.

But, for now, I was resistant. How could my illness be like any other, but not definable or testable? It was in this cognitive dissonance that I found myself on a TV shoot, sitting halfway up a spiral staircase, caught between fact and fiction. As I watched my old story being enacted around me, the pressure of a new and much scarier story was starting to build. If illness wasn’t the root cause of my suffering, what was?

* * *

Epiphanies are less a sudden bolt of novelty, more an arrival at a place where a part of you has been waiting for a long time. After Pure came out, the village that had sprung up around me, in which there was always something to do, some engagement to make, disappeared, and I reached rock bottom. It’d been 18 years since my intrusive thoughts had started. My entire adult life. I was so dissociated from the pain of this reality that I was self-harming again.

Having read about promising findings from research into psychedelics, and figuring I had nothing to lose if I lost my mind, I went to the home of a couple of hippies in Amsterdam and did a big dose of psilocybin, the psychoactive compound in magic mushrooms. (The psychological risks of doing this are serious; I recommend careful research.)

At the peak of the trip, I saw a terrifying vision of my mother getting pulled into a colossal black hole in the sky. An image that I then realised represented the cosmic loss I’d felt throughout childhood, as I’d countless times watched her getting dragged off to psychiatric hospital, or drugged into catatonia. When I came round, I was not “cured”, but I had new perspectives. There was never anything wrong with my brain; a fear of separation lay at the core of my problems. An internal stuckness that had never changed, even as I appeared to be flourishing.

The following year, with my intrusive thoughts still gnawing, I landed a job as a writer on a Netflix sci-fi series, a role refreshingly removed from my life of mental health advocacy. “What happened here?” a colleague asked innocently on set, pointing to the scars on my arm.

“I used to cut myself,’ I said. I didn’t tell her how recently.

She glanced around. No one nearby to rescue us. “Really?”

“Really,” I said with a reassuring smile.

There was an awkward silence, which I didn’t fill, since the explanation I would have once filled it with – “I was mentally ill” – no longer felt right. I was relieved when we were interrupted by another colleague.

In that silence I felt the absence of the medical paradigm I’d dismissed, which, for all its faults and its mischaracterisation of my brain as diseased, had provided an easy way to communicate. So I set out on a mission to draw a new map, interviewing experts in neuroscience, psychedelics, Buddhism and trauma. I did loads of MDMA (ecstasy), both casually and in underground therapy. I meditated. Slowly, a new sense of meaning started to emerge. Having not long ago felt so disconnected that I hurt myself to feel alive, a realisation started to dawn: I am not separate from the world.

* * *

The obvious insight that my ego had been protecting me from was that my mental health was not separate from my family’s; Mom’s depression was not separate from our financial hardship, which was not separate from decades of industrial privatisations that devastated the Midlands. And none of this is separate from my inscrutably complex neurobiology, which itself is a co-evolving story with everything around me.

This is what I think is wrong with the medical model: a failure to understand mental health in context. An assumption that a disorder is a “thing” that an individual has, that can be measured, independent of subjective experience. The trauma model can be just as reductive, turning healing into an individual consumer journey and ignoring the environmental conditions in which wounds form. This has empowered professionals to decontextualise distress from the lives of those who experience it; to create pseudo-specific taxonomies of mental disorders. Diagnostic manuals have for decades been giving well-meaning psychiatrists and psychologists the illusion of explaining the suffering of the patient sitting in front of them. This system has hurt none more than those facing social adversity: financial deprivation, poor education, racial discrimination and so on, who are pathologised as though their reactive stress, and not the things to which they’re reacting, were the problem.

Mom’s hospital admissions were cyclical, happening annually for a run of several years. Once, when I visited her in late December, I struggled to contain my emotions on seeing the bittersweet Christmas cards that the patients had made and stuck to the wall. There was a phrase I heard Mom say to doctors during those visits: “I can’t cope.” It was taken as symptomatic of the illness they said she had: bipolar disorder. It was never taken at face value, as a rational statement from a person who saw their struggles clearly. Many are saying something similar. In 2024, millions of British people are lonely. In Europe, antidepressant use has doubled in 20 years. Globally, someone dies by suicide every 40 seconds.

“I’m troubled that we’re telling people who’ve got genuinely difficult lives that the problem is inside their brain rather than outside in the world,” I said to Canadian doctor Gabor Maté when I interviewed him.

“It’s poor kids and kids of colour who are most likely to be diagnosed and medicated,” he replied. “This is trying to deal pharmacologically with what is essentially a social problem … All those years, when you were told that you had a biological disorder, did anybody ever tell you that your brain is shaped by the environment?”

“No,” I replied.

“That’s what the science has shown for decades.”

So why wasn’t I told? The answer to that is complex, and I’m suspicious of cartoonish portrayals of psychs pushing biomedical agendas for profit. Those I’ve interviewed have largely been compassionate and nuanced. But many are also badly incentivised and reluctant to scrutinise their practice.

In academia, psychiatrists will claim that criticising the biomedical model is knocking down a straw man, since they long ago started considering psychological and social factors (what they call a biopsychosocial model). But I’ve seen little evidence of this shift. In England, we’re still five times more likely to be prescribed psych meds than therapy. And the discredited chemical imbalance theory (that depression is caused by a lack of serotonin) is still listed on half of all antidepressant leaflets.

Meanwhile, in clinic, patients’ opinions routinely matter less than those of doctors. Once, when Mom told her psychiatrist that therapy wasn’t helping, he scoffed: “Maybe the problem is your attitude?” I wanted her to stop being stubborn and do what the man with the qualifications said. The medical model is insidious – it gets into people’s relationships, influencing the way we frame those we love. The rational bit of me knows that I was a kid and couldn’t have understood these things; the emotional bit of me feels I let her down. I would become familiar with this power asymmetry in my own interactions with doctors, where subjective descriptions of my problems were repeatedly, often grandiosely, presented to me as objective explanations. One hallmark feature of mental illness is mistaking our models of reality for reality itself. Interesting that it’s also a hallmark feature of our mental healthcare.

I’ve fallen in love with a metaphor that gives me a balm for some of this. Writer Charles Foster says that true sceptical science embraces mystery. It is, he says, prismatic. “It takes a prism to show that white light is anything but white: that it’s composed of many colours.” If we’re to overcome our mental health crisis, we need to think prismatically. We need to resist simplifications and be inspired by the certainty that we are missing some richer shades of complexity on the side of the prism we can’t see.

If the medical model is willing to examine its assumptions, it may admit that its research is often a repackaging of knowledge that the west has forgotten or destroyed. Every year, studies are published “proving” that things like nature, creativity, exercise and community make us happier, framing them as prescriptions for ills rather than age-old preventives.

If the trauma model does the same, it may admit that searching for causal agents in the past can facilitate dissociation from normalised dysfunction in the present; from the miseries of consumerism and the 40-hour working week; from the fact that many of us live without meaningful relationships in what psychiatrist Bruce Perry chillingly calls “relational poverty”.

“In Tanzania, everything is communal,” said healer Euphrasia Nyaki when I told her my story. “If my mother was taken away, my aunts and grandmother would take over. Grandma used to live next door. Mama is the only mama, but at least you would have some resource to help you cope. That’s a big difference from the western culture to indigenous communal culture.”

I’ve heard it said that modern society, having forgotten it broke people into pieces long ago, now sits scratching its head wondering how to put them back together. But in that head-scratching, perhaps there’s an opportunity for change.

* * *

I’m going to throw up, I thought, as I took my last mouthful of mushrooms. It was 2023 and I was at a psychedelics retreat. I’d already done two years’ therapy with an underground guide, working with MDMA, alone and in combination with psilocybin. I was already feeling a lot better. My sleep had improved. Incredibly, my intrusive thoughts were mostly gone. I could be uplifted by the eye contact, voices and touch of others. My nervous system felt alive. But a part of me still felt stuck and I wanted to understand why.

When the trip began, with astonishing intensity, I met a part of me I never knew existed. A little free-school-meals kid with a bowl-cut fringe, who had insisted on staying in the past for 25 years because she was waiting to find out if Mom was coming home from mental hospital. With its Gordian knot of doubts, OCD had attempted to distract me from this worry, or contain it, or otherwise put a story to it; to locate the source of uncertainty in myself, which I could control, rather than in the outside world, which I couldn’t.

Growing up, I was sold the idea that the only way to get people to take your mental struggles seriously is to call them illness. Paradoxically, it was only when I abandoned this idea that I reached a deeper appreciation of the seriousness of my suffering and could understand: my thoughts are not “me”, it wasn’t my fault. My disorder was not a disease or an enemy to be fought, but it was real. It was the part of me who always knew I was worth protecting.

To deconstruct my definition of suffering as mental illness was also to deconstruct my definition of getting better. If healing doesn’t mean a reduction in symptoms, what does it look like? I wasn’t going to find out by tripping or reading books or having therapy, but by stepping away from it all and living. The medical model had taught me everything about being ill, and almost nothing about being a healthy, well-adjusted grownup, who has a sense of agency and accomplishment, whose relationships are infused with trust that reaches right down to the bones, heart, lungs, tummy.

I started to feel like that grownup only after I’d brought the youngest, most vulnerable parts of my psyche into the light. I felt it last Christmas, sat next to Mom on the sofa. She was laughing at some silly thing my brother was saying. I hadn’t had any intrusive thoughts. Not a single one all day. In their place were small, new experiences of connection that’d always been there: the warmth of her hand, the vibration of voices in my chest.

• The Maps We Carry by Rose Cartwright is published by HarperCollins at £16.99. To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.

In the UK, the charity Mind is available on 0300 123 3393 and Childline on 0800 1111. In the US, call or text Mental Health America at 988 or chat 988lifeline.org. In Australia, support is available at Beyond Blue on 1300 22 4636, Lifeline on 13 11 14, and MensLine on 1300 789 978.