"I was looking down thinking, 'Man, this is just easier this way,'" he said in 2004. "You have to be mad, you have to be insane, to despair in that way. But that is the height of spiritual bankruptcy. There's nothing left."
That "spiritual bankruptcy" led him to re-examine Christianity, and ultimately to create "The Passion of the Christ," but it appears that his struggle is not yet over.
Psychologist Drew Pinsky said he thought that Gibson had made so many films about suffering because addiction made him suffer each day.
"A lot of people don't realize addiction is a biological disorder of the reward system in the brain," he said.
"Shame is one of the profound feelings that people with addiction have. And when they find they transcend an experience in spirituality and they find connection with sober peers, they're accepted and the shame tends to lift."
Gibson, the father of seven, said to ABC News that his wife Robin of 26 years had stood by him through his battle with addiction.
"She's the best friend I've ever had," he said. "She's just great. And would be there completely, 100 percent, 110 percent. And to put up with me, that's already a tall order. So, hey, I'll spend the rest of my life giving her medals, more precious than jewels."
Now, Gibson will once again try to overcome his addiction.
"You know, I'm not a done deal. I'm a work in progress," Gibson said in 2004. "And I'm extremely flawed. And I better continue to think that way, too, because -- because it's the truth."
After Gibson's arrest, some critics wondered whether Los Angeles police initially tried to cover up Gibson's arrest and behavior.
"The deputy who made the arrest came in with an eight-page report," said TMZ.com managing editor Harvey Levin.
"And ultimately his superiors looked at it and said -- 'You've got to rewrite this report. It's too inflammatory. There's a lot of tension now with the Israelis, and Mel Gibson did "Passion of the Christ," and we don't want to inflame the Jews around here over a drunk driving arrest.' So they ordered him to rewrite the report, taking out all of this incendiary information that the officer had written down."
Levin did not tell ABC News how TMZ had obtained the report.
Ironically, Gibson has used his star power to help the Los Angeles County Sheriff's Department in the past.
He even made a promotional video on behalf of one of its causes.
Sheriff's officials say that the DUI investigation is continuing, and that an internal investigation may be started.
A sheriff's official said Gibson was stopped at 2:30 a.m. on Friday for driving 87 mph in a 45 mph zone not far from his Malibu, Calif., home. The sheriff's office insists that Gibson was treated like everyone else and that his arrest occurred "without incident."
"When I say there was no incident," said Steve Whitmore, a spokesman for the sheriff's department, "yes, as far as we can tell, as far as what we know, facts substantiated by facts, that there was no use of force." Another spokesman for the sheriff's department told The Los Angeles Times that there was no cover-up.
Levin said he was "not picking up what they're putting down" and said to ABC News that the sheriff's department was covering up the incident.
"They just lied and they got caught in the lie now, and they're trying to scramble," Levin said. "Because obviously what this looks like is the sheriff's department is protecting celebrities."
ABC News' Miguel Marquez contributed to this report.