THERE is, very likely, a deliberate irony in the title that Robert Downey Jr has chosen for his first album. It’s called The Futurist, not, I’d guess, because he is interested in a half-forgotten art movement, but because he knows everyone thinks only of his past. I suppose things could be worse: that past — the drug abuse, the rehab, his incarcerations, his firing from Ally McBeal — could be his present. It is not so long ago that Vanity Fair compiled a profile of one of America’s best but most troubled actors from prison.

Our venue, mercifully, is his record company’s hip little studios in Santa Monica. Here I find Downey — still Hollywood handsome but, at 39, crinkling round the eyes and whitening at the temples — jabbing a fork into a salad. When he has finished, its foam container is converted into an ashtray. Addictive personalities never become non-addictive, but the successful ones divert their obsessions to lesser evils. His, I would guess from his wiriness, are nicotine and exercise.

He has just come from the gym, where the TV has been showing a mocking countdown of celebrity misdemeanours. When he left the programme had reached No 70. He assumes that his own would have ranked higher. And which would they be, I ask. “Maybe the Palm Springs shenanigans,” he says, referring to his arrest during Thanksgiving 2000 when someone — perhaps his own dealer — tipped police off about the cocaine and metamorphine in his hotel room. “Or maybe the Goldilocks incident in Malibu.” In 1996 neighbours found him, after a particularly confused night, asleep in their 11-year-old son’s bed. “They have a cornucopia of choices because public humiliation until recently was a big theme of mine.”

Did he feel humiliated? “I felt like Sir Walter Raleigh a bit, except that I didn’t bring tobacco to the New World or do anything particularly innovative. I was just kind of dizzy, wondering what the hell was going on.”

Yet not, he concedes, all the time. In film after film, from Short Cuts to Wonder Boys, he pitched up on set sober and on time ready to deliver high-definition performances that tended to leave his co-stars looking feeble. In 1992 he was nominated for an Oscar for Chaplin and, with better luck, he might have been nominated again.

“Through all that tough stuff I stayed rooted enough to be able to complete projects, father a kid and purchase furniture,” he says. And he was married for several years. “But I wouldn’t recommend that to anyone, unless it was exactly what they needed, but, you know, long periods of time in something fairly akin to purgatory is a great remedy for a life that’s short on gratitude.”

At such moments in our hour together I wonder what Downey is on about. At others, as he gabbles away, pummelling cigarette stubs into the salad shreds, I wonder what he is on. He insists nothing, but that’s not quite true for, suddenly, he opens a canister of multicoloured pills and swallows a handful. My God, what are these? “Herbs, calcium, E vitamins.”

How does he get his highs, now that he’s a narcotics-free zone? Mainly, he says, from recalling how close he came to writing himself off. It’s like the thrill you get from escaping a car crash. “For those 15 seconds afterwards you’re so appreciative. Adrenalin is shooting up your meridians and you go ‘Wow!’ Ten minutes later you are beeping the prick in front of you.”

Coincidentally, he says it was while driving a real car a couple of years ago that an epiphany occurred. He was not on probation or parole, not in a relationship. He was free, in other words, to misbehave. So there he is, driving his Lincoln in Venice, California, when a cop stops him. On his front seat, poking out from a bag, is his paraphernalia, “nitrous oxide, glass stems, pipe screens, the whole thing”. And the policeman doesn’t look in the bag, just tells him to fix his front number plate. A couple of days later he is driving along the Pacific Coast Highway, still not having used the kit, and he cottons on that the universe has given him another chance.

So he threw the drug stuff out? “Well, it found a happy home.”

Nothing goes to waste? “More the material itself went to waste,” he says, suddenly censorious of his former crowd. “It was imperative that I not interact with the type of people who’d want to pick up the slack. So now I can say with some assurance, not with the bravado or bullshit that comes with the untrustworthy alcoholic archetype, that — unless I feel the need to start writing a sequel to the whole story, which I don’t — it’s behind me.”

The whole story is a lengthy one and began soon after he was born into a family of “beatniks” in Greenwich Village, New York. They had an unconventional take on child rearing. His father, Robert Sr, an underground film-maker, decided it would be “cute” to treat his six-year-old to a toke of marijuana. The family moved often, heaping more confusion on to their son’s life. (A psychiatrist once told Downey that he had been “raised by wolves”.) In California he dropped out of high school. He found in his chosen career as an actor that he could snort cocaine and drink all day without obvious malfunction. Aged 22, he played a coke addict in Less Than Zero.

Things began to unravel only after Chaplin, which was when he turned to heroin. It is a tragic coda to a magnificent performance, for, should anyone doubt Downey’s talent, they need only fast-forward to the moment when, as Chaplin, he arrives in the Californian desert and, impromptu, does his entire, splay-legged, umbrella twirling act for the director. In that moment Downey announced not only the tramp’s genius but his own. Sadly, the applause the performance earned was not enough. As he saw it, it just condemned him to more hard work: “There’s the high and there’s the buzz and there’s the achievement and there’s the accolades and then you are really, really, really supposed to go right back into f***ing training again. That’s the point that I missed.”

Explore Film

• Film Reviews

• Trailers

• DVD

• London Film Festival

Editor's choice

• The super cool Vampire Weekend
• Streep and Baldwin get complicated
• Guy Ritchie on Sherlock Holmes