It was 4.30am on a dark September morning and I was suddenly awake. I knew straight away that something was wrong.

The house was quiet and I could hear the steady breathing of my wife in bed beside me, but I was feeling extremely strange. My pulse was pounding fast, I felt hot and cold all over, my skin was prickling and I was sweating like a runner.

I swung my legs over the edge of the bed. I don’t express emotion on the whole, but tears began running down my nose, mingling with the rivulets of sweat. I drank some water. All at once something very bad happened: I was overtaken by the alarming conviction that I was about to die. The sensation was real and frightening. This was it.

I shook my wife’s arm. “Wake up!” I gasped. “I think there’s something wrong with me. Something’s seriously wrong.”

She woke up and listened to me calmly. My wife is a positive, cheerful person, unlike me. I am cool, precise, ironic, a watcher in the shadows, prone to low moods and restlessness. She considered me for a moment. Then she said, matter-of-factly: “You’re having a panic attack.”

The attack seemed to come out of the blue, yet there had long been signs that something was wrong. For a while I had been waking in the middle of the night, lying there, staring at the ceiling, turning things over. From a golden sunset to a good meal, I found life unrewarding. My hobbies had lapsed: typography, sleight-of-hand magic, and British road signage had been the focus of my interest for a long time, but now they disgusted me a bit. Family friends found me hard work. During one pub lunch, after I’d wolfed down a sandwich while they laughed and chatted over their roast beef one of them asked me sharply, “Why do you never savour a meal?” My aloof social disposition was damaging friendships. People have told me that when I think I am smiling, I’m actually frowning. I was astonished recently when somebody showed me photographs of myself at a wedding. Everyone around me was smiling beautifully. I looked positively unpleasant.

Yet I was happily married, I was fairly healthy, and some of my books had been bestsellers around the world. So why the constant knot in my stomach? In the morning I rolled up to see my GP. She asked me how I was.

“I don’t really know,” I said. “I just don’t feel right: sort of ‘empty’. I’m finding social situations increasingly hard.”

After examining me she nodded decisively. “I can’t find anything physically wrong. But you do seem remarkably tense. Are you an anxious person, would you say?”

I hadn’t really ever thought of myself as anxious, but maybe it would explain the constant tightness in my chest, the pacing up and down, my suppressed rage at a friend’s one-minute-late arrival for lunch.

“I suppose I could be described as anxious, yes,” I said.

“What makes you anxious?”

“Being alive in the world.” I got a genuine laugh in response.

At one party I said something so badly wrong that the hostess burst into tears. “Get him out of my house!” she cried

My GP explained that we’d leave antidepressants until we’d tried a few sessions of cognitive behavioural therapy. It didn’t do much for me, but in my last session the light finally came on when my therapist said: “I think something else might be going on here, Tom.”

I braced myself. “You say you find social situations ‘taxing’: you’ve taught yourself how to fit in but you feel as if you are always pretending – people find you aloof; you dress oddly; and you have a special interest in road signs – in one session you talked at some length about the London tube map.”

“It’s a diagram, really, not a map,” I said.

“There! You’re a details man and a rules man: definitions, commas, errors, corrections - didactic interruptions. Now taken together I think all this might be pointing to something. I think you might be on the autism spectrum – Asperger syndrome.”

“No,” I insisted, “I’ve worked with people who have Asperger’s and I’ve read about it. I’m not like that.”

The therapist drew a line. “The people you’ve met might be down here on the spectrum. At the further end. And you might be up here. A bit harder to spot. Have a think about it, Tom. Go away and read about it and come back and tell me what you think next time.”

I’ve always known there was something different about the way I relate to the world. I seem to experience things more intensely than other people. I have trouble with noises and smells. I get sensory overload in supermarkets: the flickering lights, all those people, all that racket, the turmoil of all those shelves, all those labels, all those smells, all that advertising.

But worse were the social troubles. Chatting I found impossible and for as long as I could recall, parties had been a special kind of torture, provoking silent dread days ahead. I vividly remember my own seventh birthday party watching the other children playing games and having fun while I stood uncomprehending and resentful at the edge, an invisible force field somehow separating me from them.

Many years later when I was studying art at university, bohemian parties were frequent. I would force myself to go but usually ended up alone, looking through bookshelves or staring into my glass. I always seemed to say the wrong thing and people found me brusque, abrupt, or stupefyingly rude. At one party I said something so badly wrong that the hostess burst into tears. “Get him out of my house!” she cried, and within seconds I was on the doorstep, coat in hand. I was obliged to walk three miles in the rain back to my digs.

I am sometimes accused of being overly critical. I often have to button my lip at somebody’s slipshod cooking or a language error in a wedding invitation. There is no good to be had from pointing out these things. I have had to learn that people do not want you constantly criticising them and underlining their weaknesses. A woman once told me, “You spoil everything.”

I’ve always been good at other things. From an early age I’d had a bent for the geometry and mechanics of language. I enjoyed the pernickety details of style, and found etymology rewarding. I saw linguistic communication as an engineering job and had a knack for identifying the crucial architecture of a sentence, just as an engineer might pick out the vital members of an iron bridge.

Facebook Twitter Pinterest ‘Professor Uta Frith says that Sherlock Holmes acts like someone with Asperger syndrome’ ... Benedict Cumberbatch as Holmes. Photograph: BBC/Hartswood Films

As I read up on Asperger’s, I discovered that one of its main features is the drive to look uncommonly deeply into preferred subjects, often mechanical or systemisable ones. It might be bus timetables, the human body, entomology, etymology, Dewey numbers, tornadoes, car engines, flags, films, fairground rides or any of a thousand other quirky subjects. One of my special interests is Sherlock Holmes. Oddly enough, in her 1989 book, Autism: Explaining the Enigma, Professor Uta Frith says that Holmes acts like someone with Asperger syndrome; his absent-mindedness in relation to other people and his single-mindedness about special ideas are, she says, classic traits. Holmes is an expert in practical chemistry, as well as an authority on newspaper typography, cigarette ash, the sonnets of Petrarch, secret writing, bicycle tyres, music and the varieties of London mud.

Engineering and music crop up often in autistic families, and literature, too, is a rich field. Though one cannot diagnose a dead person, the signs of autistic traits among some eminent writers are there. WH Auden displayed plenty of features of the condition. He had a gawky gait, collected hats, dressed strangely – wearing carpet slippers in public – spoke in a rather monotonous voice, and displayed a marked lack of eye contact. He had another quirky trait: he liked to sleep beneath weighty blankets, and once went to bed underneath a rolled stair carpet; another time under a heavy oil painting.

Another language engineer was Philip Larkin. An unsociable man, he had interests in ties, crime fiction and Beatrix Potter. A great collector of souvenirs, and particular about their placement, Larkin was, tellingly, a librarian. His secretary at Hull University said that when the library was being built he used to come in every Saturday, dressed in a weird combination of, say, a pink jumper and yellow socks, to photograph the progress of the girders.

Facebook Twitter Pinterest Ties, crime fiction and Beatrix Potter … Philip Larkin in 1979. Photograph: Jane Bown/The Observer

I too have a fascination for civil engineering projects. Among my other special interests are vehicle numberplate typography, the shapes disguised as letters used on eye-test charts, and above all British road sign design. As a boy I fell in love with typography: a world governed by system, formality, detail and rules. After all, the full stop at the end of this sentence is not just a dot; it was drawn on a grid by someone. I find full stops easier to get on with than people.

Asperger’s was a richer and more varied condition than I’d thought. And if the therapist was right, it would have been affecting me my entire life, souring my relationships; getting me into scrapes; winding my spring. I decided I had to get a proper diagnosis.

I contacted Sarah Hendrickx, an expert in autism. Maybe she could shed light on my trouble understanding other people and getting on with them. After various questionnaires and hours of cross-examining me, she told me plainly: “I think you have Asperger syndrome.”

More formally, my “Autism Spectrum Assessment” said this:

Tom is a concrete thinker, with difficulties in reading people and social signals, which results in social awkwardness and difficulties in understanding the emotional perspectives of others. He has some lifelong intense interests (including road signs and type). Tom’s experiences of anxiety and depression could be related to this atypical cognitive profile and its impact on a sense of “fitting in”.

Asperger syndrome: so that was it. At last, this condition made sense of the non sequitur of my often lonely and overridingly out-of-sync life. I wasn’t, as I’d thought, mad; I wasn’t, as I’d thought, alone. I had unwittingly been autistic my whole life.

After my diagnosis, I decided to get some fresh air. I had a lot to think about, but rather than ruminating uselessly I felt a comforting peace descend around me: a novel sensation. My depression, which had been with me for four decades, simply began to evaporate.

• Keep Clear: my adventures with Asperger’s by Tom Cutler is published by Scribe.

