I’ve been an academic in the humanities now for almost 20 years, and so telling people that you’re writing a book called On Drugs invites an inevitable series of nods, smirks and winks – of jokes about doing empirical “research” in the area, of possibilities for applying for grants and getting funding. (While an addict, I would have certainly appreciated more funding.) One colleague, on hearing I was writing this book, joked that I should make up something “juicy”, like that I smoked crack, almost died and “went through some fancy rehab”.

The fact, though I didn’t say as much, was that I did smoke crack, did almost die and had been through a fancy rehab – several times. For over a decade I spent half my waking hours acquiring and using drugs and the other half trying to hide that fact. After a decent apprenticeship, I got good at both. And yet the patterns of thought and behaviour that surfaced during my years of addiction weren’t totally alien to me. I’d long seen life, as far back as childhood, as a complex and fraught series of acquisitions and ingestions, of obsessive consumption and the rigidly patterned structuring of my environment and behaviour – as well as an ongoing and dedicated dissimulation of these.

I’ve often wondered if my desire to write about all of this is some kind of distancing mechanism

There is no shortage of drug memoirs in bookshops. We’ve all read examples of the genre. I’m convinced that, most of the time, the main thing that drugs can teach us about the universe is what it’s like to be on drugs.

Mine is a particular kind of drug book. I am not Tony Montana and my story is not Requiem for a Dream. I never took hostages, stabbed strangers or robbed convenience stores – and yet, much of what the book recounts has been painful to bring to mind. I abused drugs and alcohol to the point of near-death for around 20 years and very little of it now strikes me as admirable. There is no context in which one’s own account of drinking methylated spirits can sound dignified, let alone heroic or “cool”. And there is little point in denying my fear that people who know me will look at me very differently as a result of what they can now read about my life.

The world sometimes pretends it’s making peace with a variety of previously embarrassing pathologies: that we have destigmatised mental illness, reduced the shame of those with depression, welcomed those with eating disorders – and those with addictions. I don’t think that’s even remotely true. If this kind of recuperation has begun, it is a very long way from being completed.

I’m no longer a drug addict, or as the recovery community prefers it, more cautiously, “in active addiction”. And I’ve often wondered if my desire to write about all of this is some kind of distancing mechanism, a forcible punctuation point, a guarantee of being or remaining clean – some statement of stable personal identity that the words would safely chain me to. Each time I wonder this I’ve reached an identical conclusion: probably not. There’s a derangement that accompanies addiction and obsession, a narrowing of vision through which every cognitive and linguistic ability, every available finance and bodily effort, every form of moral compromise, bows down before what is craved. It isn’t so easily deterred. It’s not made nervous by punctuation or by gossiping about it in the past tense.

Addiction does thrive on secrecy though, on seclusion and mingling with shadows. It requires walls be erected between an addict’s using and non-using lives. Until it almost destroyed me, my addictions only rarely disturbed the neighbours. Very few people got to see much of the picture, and nobody ever got to see the whole thing (and I include myself in that).

One of the oddest senses I got while writing On Drugs was the question of who I was writing about. Although I use the pronoun “I”, the person I describe in the book is more and more a stranger to me. This is not merely a convenient way to distance myself from someone who now embarrasses me (though it’s a pleasing side-effect). It’s that the person does things that I don’t do, thinks in ways I don’t think, and is gripped by obsessions I no longer have, except perhaps in rare flashes of reverie, romantic and selective black-and-white stills of earlier times when my skin was less crumpled and my sense of immortality stronger. I can recognise the desires intellectually, but they now seem to me inanimate, petrified.

Distance has brought the benefit of being able to describe what happened to me, and what I did, more like an anthropologist. But it also makes it harder to get back to where I was, to inhabit the space of addiction and near-collapse, of gathering pace in a slide towards death. I still understand that this was the case, but I can’t so easily access what it felt like. Nonetheless, even while those patterns of thought and behaviour upon which drugs found fertile ground are now at rest, I know that drugs left an imprint on me the size and depth of which is impossible to delimit. So although I’m no longer high, and what concerns me in my book isn’t restricted to addiction, it remains decidedly a book on drugs.

• In Australia, the crisis support service Lifeline is 13 11 14. In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. Other international suicide helplines can be found at www.befrienders.org

• Chris Fleming is the author of On Drugs, available now through Giramondo