Innerspace: "The Reason I Jump"

The Reason I Jump is an adaptation with a difference, connected to the way its subjects look at and approach the world. The seasoned British documentary maker Jerry Rothwell (Deep Water, Heavy Load) has gone after and captured the spirit of his source material, a 2007 memoir by Naoki Higashida, an autistic Japanese teenager attempting to explain himself, and thus the fundamentals of autism, to non-autistic readers. What made the book so useful to students of autism was that it was among the first to be written by someone who'd grown up with the condition; furthermore, Higashida was young enough to vividly remember and precisely evoke his growing awareness of being autistic. The novelist David Mitchell, who produced the book's English-language translation with his wife Keiko Yoshida, describes Higashida as providing "a map of his mind", and thus presumably a clearer path into and through hitherto undercharted territory. A reading from the introduction sees the author inviting the reader to "have a nice trip through our world". Rothwell takes this as a cue to have a nice trip around the world, seeking out autistic teenagers in India, the US, Africa and the UK - Higashida's fellow travellers - and inviting them to communicate, either through word or gesture, the truth of their own being. It's a project that must have been founded on the utmost trust: I'm guessing Rothwell had to offer extra assurance that the presence of a camera crew in these kids' front rooms - or even just one man with a camera - wouldn't upset any daily routine or equilibrium. Most of the outbursts that camera captures are those of joy: subjects seeing and hearing so much they feel compelled to give a shriek of delight. Sometimes, though, we see tantrums, and true as they are to the reality of living with autism, these aren't always so pretty.

As Higashida explained in his book, one useful way to look at autism is as being bombarded with too much unfiltered information - as if the world were a relentless, multi-directional, open-ended Twitter feed - and consequently falling subject to a heightened sensitivity. This is a state the cinema can easily replicate, and which Rothwell's cinema replicates very well indeed. We get close-ups of details, of a road, a rainstorm, even a pencil; an especially evocative soundscape, in which the squeak of an underoiled swing registers as just a decibel or two too loud; and an illuminating editing strategy that mimics the scattered memories that are a symptom of autism, where recollections aren't dated and filed away as they would be in neurotypical minds. Often, that results in a creeping anxiety: Rothwell notes as much via a long observational sequence that quietly watches Broadstairs lad Joss being consumed by unease as dad Jeremy takes a few minutes longer than expected to pick up takeaway from Pizza Express. I think most of us will have found India and Africa overwhelming on a first visit; now imagine living there 24/7 with a mind hotwired to absorb every last detail on a bustling Delhi or Freetown thoroughfare - and to do so all at once. The film has been very precisely calibrated to encourage the viewer in Row G to make that imaginative leap (which is also, not insignificantly, a leap of empathy) alongside it: it knows this condition is inextricably tied up with issues of communication.

The puzzle autism presents is how to get what's in there out to the neurotypical world - that's the breakthrough Higashida wanted to make when he sat down to write. His autism, naturally, isn't quite the same as anybody else's, which is one reason why Rothwell was wise to seek out and document so many other experiences; he senses the memoir can only be approached as a guidebook, not a treatment manual. So we witness very different levels of autism, requiring very different levels of care and attention. Joss merrily converses with Rothwell behind the camera; but Ben and Emma, two friends from Virginia, have to spell out what they want to say letter by letter. That has necessitated an education that's only just become available to Jestina in Sierra Leone, and only then because her crusading mother made it so. Wherever we go, in this world or within these heads, it's clear autism demands its own time and space; fortunately, Rothwell has the patience to watch and wait, to see what his subjects have to tell him, rather than speaking in their place. You emerge from The Reason I Jump having borne witness to as much an education on the subject of autism as Blind Sun and Notes on Blindness were on the altered perspectives brought about by sight loss. Early on, Joss's dad Jeremy confesses "I'd like to be inside his head, just for ten seconds, just to see how he sees the world". Rothwell goes 492 times better, in putting us there or thereabouts, with great delicacy, for a full 82 minutes.

The Reason I Jump opens in selected cinemas from Friday.