Though Robin Williams quit cocaine and alcohol unassisted in 1982, he looked to rehab for help years later

Robin Williams’ public life had a quiet personal current running through it for decades: his struggles with cocaine and alcohol abuse.

The comedian and actor, who turned 63 in July, was found dead Monday in what authorities called an apparent suicide due to asphyxia at his home in Tiburon, Calif. He’d “been battling severe depression of late,” his publicist Mara Buxbaum told The L.A. Times.

The “Mork & Mindy” star quit cocaine and alcohol cold turkey six months ahead of the April 1983 birth of his first child, Zachary, with first wife Valerie Velardi. “Mork,” which along with his Grammy-winning album “Reality … What a Concept” propelled him to stardom, had wrapped its TV run in May 1982.

“No visit to the Betty Ford Center, no therapeutic support,” a friend told People in 1988. “He just quit.”

Not coincidentally, Williams’ decision also came after the March 1982 death of John Belushi; Williams had been at his friend’s Chateau Marmont bungalow in the hours preceding the “Saturday Night Live” star’s speedball overdose, though he left hours before the death.

“The Belushi tragedy was frightening,” Williams told People in 1988. “His death scared a whole group of show-business people. It caused a big exodus from drugs…. I knew I couldn’t be a father and live that sort of life.”

He also revealed details about his drug use to The L.A. Times in 1991.

“It was a strange thing because my managers sent me to this doctor because they said I had this cocaine problem,” Williams said. “He said, ‘How much do you do?’ And I said, ‘A gram every couple of days,’ and he said, ‘You don’t have a problem.’

“That was before they’d started to acknowledge it was psychologically addicting. And then at a certain point you realize, maybe it is. Physically I’m not craving it, but mentally I’m really thinking it might be a good idea.”

The man who would go on to win an Oscar for “Good Will Hunting” stayed sober for two decades, until he was filming on location in Alaska in 2003.

“I was in a small town where it’s not the edge of the world, but you can see it from there, and then I thought: drinking,” Williams told the Guardian in 2010. “I just thought, hey, maybe drinking will help. Because I felt alone and afraid. It was that thing of working so much, and going … maybe that will help. And it was the worst thing in the world.”

Though he knew in a week he was in trouble, he told the UK paper, it was three years until he entered the Hazelden residential rehab in Springbrook, Ore. It reportedly took a 2006 family intervention to get him there, and in 2010 he said he was still going to Alcoholics Anonymous meetings weekly.

Williams never went back to cocaine: “I knew that would kill me,” he told the Guardian.

Unfortunately, stress from his drinking and subsequent trip to rehab ultimately claimed his second marriage, People reported in March 2008, when Marsha Garces filed for divorce after 19 years of marriage to the comic.

He remarried in 2011, to graphic designer Susan Schneider.

Last month, it went public that Williams was taking part in Hazelden’s Lodge “experience” in Minnesota. The facility bills the program as a place where people who are living sober can come to touch their 12-step bases, with meditation and spiritual work part of the mix.

“After working back-to-back projects, Robin is simply taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud,” Williams rep Rachel Karten said on July 1.

“The Crazy Ones,” Williams’ return to series TV, which costarred Sarah Michelle Gellar, was canceled in May.

A publicist for Williams did not respond to a Monday request for information about when the actor finished the Lodge program.

Authorities did not mention alcohol or drugs in connection with Williams’ death, though toxicology tests will be done as part of an autopsy.