UPDATE: According to a golf.com report, the leave of absence is related to a positive cocaine test. Apparently, this is the third drug test Johnson has failed.

Dustin Johnson is taking a leave of absence from golf to seek help for "personal challenges," putting him out of the PGA Championship and raising questions about whether he will be at the Ryder Cup at the end of September.

In a statement Thursday from his agent at Hambric Sports Management, the 30-year-old Johnson said his leave of absence was effective immediately. It did not indicate how long he would be out of golf. Johnson withdrew from the Bridgestone Invitational at the start of the week.

"I will use this time to seek professional help for personal challenges I have faced," Johnson said. "By committing the time and resources necessary to improve my mental health, physical well-being and emotional foundation, I am confident that I will be better equipped to fulfill my potential and become a consistent champion."

He asked for privacy "as I embark upon this mission of self-improvement."

The PGA Championship starts next Thursday at Valhalla, but there is more big golf to follow. Johnson, who won the HSBC Champions in Shanghai at the start of the PGA Tour season last October, is No. 4 in the FedEx Cup. The playoffs begin Aug. 21 at The Barclays.

Johnson also was No. 5 in the Ryder Cup standings, virtually certain of earning one of the nine automatic spots on the U.S. team. If he does not take play in the Ryder Cup, which is Sept. 28-30 in Scotland, he would be replaced by whoever finishes 10th in the standings after next week.

It's the second time in two years that Johnson has missed a major under curious circumstances.

He pulled out of the Masters in 2012, saying that he tweaked his back while lifting a jet ski. He wound up missing three months, and won in his second tournament back.

Johnson played in the final group in the third round of the British Open with Rory McIlroy, fading with a 71-72 weekend and tying for 12th. He missed the cut the following week at the RBC Canadian Open, and then withdrew from the World Golf Championship at Firestone.

The PGA Tour, which does not comment on disciplinary action, offered little in a statement.

"We have nothing to add to Dustin's statement, but we wish him well and look forward to his return to the PGA Tour in the future," the tour said.

Johnson is No. 16 in the world ranking with eight PGA Tour victories. He is the first player since Tiger Woods to go from college to winning in each of his first seven seasons on the PGA Tour. He lost a three-shot lead in the final round of the 2010 U.S. Open at Pebble Beach, closing with an 82. Later that year, he was assessed a two-shot penalty on the final hole of the PGA Championship for grounding his club in a patch of sand, not realizing it was a bunker at Whistling Straits.

Johnson last year got engaged to Paulina Gretzky, the daughter of NHL great Wayne Gretzky.

(Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)

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