Bob Barker privately battled Alzheimer's before his death.  

The legendary TV host, best known for the popular game show The Price Is Right passed away in August at age 99. His cause of death has been revealed as a result of Alzheimer's disease, per the death certificate obtained by TMZ. However, Barker never publicly addressed his diagnosis.

His death was first announced Aug. 26, with his rep Roger Neal sharing that Barker died from natural causes at his Hollywood Hills home.

"It is with profound sadness," the rep said in a statement to NBC News, "that we announce that the World's Greatest MC who ever lived, Bob Barker has left us."

Barker began his game show career hosting Truth and Consequences in the mid-‘50s before expanding his duties for the revival of The Price Is Right in 1972. As a fixture on daytime TV, he only missed one taping of the CBS series in his 35 years as host.

In 2007, Barker announced his retirement from The Price Is Right, handing the show over to current host Drew Carey. And the comedian honored his predecessor during the show's Aug. 31 episode. 

"Most people remember Bob from the 35 years he spent hosting The Price Is Right," Carey said. "So it's easy to forget that for 18 years, he was a fixture in America's living rooms for Truth or Consequences, a radio host before that, and a naval aviator during World War II. We'll also remember Bob for his tireless work on behalf of all animals from whales and elephants to the cats and dogs who reminded everybody at the end of the show to get spayed or neutered." 

The Whose Line Is It Anyway? alum continued, "You know, I mentioned the word 'legend' earlier and how that word gets thrown around all too much these days. It couldn't be more appropriate when you think about Bob's time on The Price Is Right."

Barker, who earned 14 Daytime Emmys for hosting the game show, was also honored with a Lifetime Achievement Emmy Award for Daytime Television in 1999 and was inducted into the Academy of Television Arts & Sciences' Hall of Fame in 2017.

"This really culminates my professional life," he reflected at the time. "It's about a nice a thing that could possibly happen to anyone in television."

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