The very subtitle of Scatterbrain – ‘how I finally got off the ADHD rollercoaster and became the owner of a very tidy sock drawer’ – is a spoiler. But if only Shaparak Khorsandi had also known from the outset that she had attention deficit hyperactivity disorder, her life would surely have been much easier.

The comedian was only diagnosed with the condition at 47 – even though quite a few people she encountered before then casually suggested she might have it. And the more she has learned about it, post-diagnosis, the more it has made sense of her chaotic, often self-destructive life. 

Though she was called ‘Scatty Shappi’ at school, her disorder was not picked up. She didn’t fit the ADHD stereotype of a wildly unruly boy. Instead ‘Does not fulfil her full potential,’ was all the teachers concluded about the easily distracted daydreamer and fantasist. The condition has long been overlooked in women for that very reason, and because women tend to be so much better at ‘masking’ behaviour that doesn’t draw attention to the underlying problem.

Khorsandi relives every cheek-reddening schoolgirl humiliation here, from spinning blatant lies about being besties with a Grange Hill star to petty theft, but that’s just level one of the unflinching honesty she brings to the page.

She became a heavy drinker to overcome anxieties about her inability to read social cues; she gave into obsessive thoughts and became an over-eater and bulimic. Comedy was the one field that suited her jumbled mind. Being in the spotlight forced her to focus on dealing with the here and now – and while sitting down to write was anathema, she could be creative on stage where all other thoughts were blocked out.

However, she admits to squandering much of her early potential in the business because she drank too much and was recklessly unprepared for every TV break she was offered. That would be worryingly close to the homework she always shunned. Her brain would never allow her to see the long-term goals of a career, just a series of brief, fun moments.

As a young woman, she got herself into some dangerous scrapes, and as an older one her undiagnosed condition, it seems, contributed to the breakdown of her marriage. Perhaps most candidly, she breaks a taboo to admit that her short temper and maddening frustrations sometimes made her a bad mother, despite her dedicated attempts to build the perfect childhood for her son and daughter.

She’s keen not to blame everything on her ADHD, recognising that people, including her, can sometimes just be pricks – selfish, rude or self-indulgent. Nor does she believe medication is the panacea, though it has helped her, as has meditation, learning not to say ‘yes’ to any project or favour asked of her, and spending more time relaxing outdoors. Most crucial is understanding what’s going on in a chemically imbalanced brain so she can work with it, not indulge it or try to down it out with booze. 

Though ADHD is not well-understood scientifically, there seems to be a genetic factor and Shaparak’s father, the dissident Iranian poet Hadi Khorsandi, had an explosively volatile temper despite his default geniality. And having to flee your homeland to find people still wanting to kill you in London can’t be good for mental health.

Bu being so upfront about episodes that must be painful to relive means Khorsandi offers a vivid, candid portrayal of what it is like to live with ADHD. Those similarly affected would surely find solace in knowing they are not alone – the comic certainly did – while for the rest of us, it offers a window into the minds of people who don’t think typically, whether that’s someone close, a colleague… or just in the abstract, with the book offering a fascinating insight into others’ lives.

Scatter Brain isn’t perfectly structured and sometimes loops back on itself, repeating ideas or similar scenarios – though that should hardly come as a surprise given the subject matter.

 But as expected of a stand-up, Khorsandi writes with a lightness of touch even when dealing with the darkest of episodes, and is always disarmingly self-effacing when describing behaviours that she now has the distance and understanding to see as irrational, sometimes comically so, sometimes disturbingly so, and quite often both at once.

• Scatter Brain by Shaparak Khorsandi is published by Vermilion, priced £16.99. 

It is also available from Amazon at £13.59.