David Cassidy gets candid with Dr. Phil McGraw about his fears surrounding his ongoing battle with dementia.
In a Dr. Phil interview that airs Wednesday, The Partridge Family alum, 66, says he was diagnosed with the disease more than two years ago, but it was foreshadowed years earlier when his mother, actress Evelyn Ward, died of Alzheimer's-related dementia in 2012 at age 89.
Cassidy reveals that his greatest fear is to be "in a place [his] mother was the last two years of her life, where I would completely disappear."
"I'd just be a burden to caretakers and couldn't walk, couldn't talk, couldn't sing, couldn't play," Cassidy says. "That's kind of my greatest fear."
In another clip, Cassidy recalls the first symptoms that alarmed him.
"When friends of yours or family members begin to say to you, 'Remember? I just told you this two days ago,' and there's no memory of it," Cassidy says. "That's when I began to be very concerned."
Cassidy's diagnosis revelation comes after several tumultuous years, including a divorce from his third wife, Sue Shifrin, filing for bankruptcy and a number of high-profile arrests for driving under the influence.
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HOLLYWOOD, CA - DECEMBER 14: Singer David Cassidy performs at Hollywood Today Live at W Hollywood on December 14, 2016 in Hollywood, California. (Photo by David Livingston/Getty Images)
NEW YORK, NY - JANUARY 10: Musician David Cassidy performs at BB King on January 10, 2015 in New York City. (Photo by Debra L Rothenberg/Getty Images)
HOLLYWOOD, FL - DECEMBER 12: David Cassidy attends Seminole Hard Rock Winterfest Boat Parade 2014 Grand Marshal Reception Honors Flo Rida at Seminole Hard Rock Hotel & Casino ? Hard Rock Cafe Hollywood on December 12, 2014 in Hollywood, Florida. (Photo by Larry Marano/Getty Images)
HOLLYWOOD, FL - DECEMBER 12: Sue Shifrin and David Cassidy attend Seminole Hard Rock Winterfest Boat Parade 2014 Grand Marshal Reception Honors Flo Rida at Seminole Hard Rock Hotel & Casino ? Hard Rock Cafe Hollywood on December 12, 2014 in Hollywood, Florida. (Photo by Larry Marano/Getty Images)
SCHODACK, NY - AUGUST 21: In this handout photo provided by the Schodack Police Department, David Cassidy is seen in a police booking photo after his arrest on charges of felony DWI, driving while intoxicated, August 21, 2013 in Schodack, New York. Cassidy was released on USD 2,500 bail and is scheduled to appear in court September 4. (Photo by Schodack Police Department via WireImage)
TODAY -- Pictured: Musician/actor David Cassidy appears on NBC News' 'Today' show on March 21, 2013 -- (Photo by: Peter Kramer/NBC/NBC NewsWire via Getty Images)
TODAY -- Pictured: (l-r) NBC News' Matt Lauer, David Cassidy, tv host George Oliphant and NBC News' Natalie Morales appear on NBC News' 'Today' show on March 21, 2013 -- (Photo by: Peter Kramer/NBC/NBC NewsWire via Getty Images)
BIRMINGHAM, UNITED KINGDOM - NOVEMBER 09: David Cassidy performs on stage during the UK Once In A Lifetime Tour at LG Arena on November 9, 2012 in Birmingham, United Kingdom. (Photo by Steve Thorne/Redferns via Getty Images)
NEW YORK, NY - JULY 19: Singer David Cassidy performs at BB King on July 19, 2012 in New York City. (Photo by Bobby Bank/Getty Images)
NEW YORK, NY - MAY 22: David Cassidy attends 'The Celebrity Apprentice' Season 4 Finale at Trump SoHo on May 22, 2011 in New York City. (Photo by Jim Spellman/WireImage)
LONDON, UNITED KINGDOM - APRIL 12: David Cassidy performs on stage at Hammersmith Apollo on April 12, 2011 in London, United Kingdom. (Photo by Mark Westwood/Redferns)
COCONUT CREEK, FL - AUGUST 13: Singer David Cassidy performs during the first hand of Real Blackjack 24/7 Seminole Casino Coconut Creek on August 13, 2010 in Coconut Creek, Florida. (Photo by Larry Marano/Getty Images)
TODAY -- Pictured: (l-r) David Cassidy and Danny Bonaduce appear on NBC News' 'Today' show (Photo by Peter Kramer/NBC/NBCU Photo Bank via Getty Images)
NEW YORK - NOVEMBER 21: David Cassidy performs at the Queensborough Performing Arts Center in Queens on November 21, 2009 in New York City. (Photo by Bobby Bank/WireImage)
TODAY -- Pictured: David Cassidy appears on NBC News' 'Today' show (Photo by Peter Kramer/NBC/NBCU Photo Bank via Getty Images)
David Cassidy enter caption here at The Langham Resort on August 8, 2009 in Pasadena, California. (Photo by Steve Granitz/WireImage)
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The former child star went to rehab in 2014, but fans began to fear for the actor and musician earlier this month when a video surfaced in which he was seen stumbling onstage during a performance outside of Los Angeles. The event led some to wonder if he had fallen off the wagon. Cassidy denies these rumors.
"He flatly denies that there was any alcohol involved in that whatsoever," Dr. Phil tells ET's Cameron Mathison.
But Dr. Phil is somewhat skeptical about Cassidy's claims of sobriety that night.
"A lot of professionals that I have talked to felt like that behavior was more consistent with intoxication," Dr. Phil says.