David Cassidy's final months: Former teen idol was terrified of suffering from dementia, was haunted by his father's death

David Cassidy spent his final months in agony as the former teen idol believed he was battling dementia, the same disease that plagued his TV star mom — and yet he was determined to complete what would be his last gift for fans.

“The Partridge Family” actor is the subject of a new A&E documentary titled “David Cassidy: The Last Session,” which chronicles the singer’s journey in addressing his memory loss, as well as his willingness to complete his last EP, “Songs My Father Taught Me.”

The special was filmed months before the “I Think I Love You” singer passed away in November 2017 at age 67. It highlights never-before heard audio tapes, as well as behind-the-scenes footage that features his story from reaching fame to hitting rock bottom.

Cassidy, who invited the documentary film crew in August, fell gravely and unexpectedly ill during production.

It was during this time that he revealed to producers that his struggle with alcoholism had continued up through the recording session, and that doctors had concluded that alcohol poisoning, not dementia, had likely been the chief cause of his tragic health decline.

Producer John Marks told Fox News he never witnessed Cassidy drinking and the fallen star truly believed his significant memory loss was caused by dementia, not liver disease, which doctors would later diagnose during his hospitalization.

“There weren’t any bottles around,” said Marks. “We could see he was having a hard time getting around. We knew that years on the road, or at least what we were told, had taken its toll on him. But when he actually came into the studio, he was there to work.

"And when he was no longer able to work, when he just felt too much pain, was exhausted, or his voice couldn’t get there, we shut down the session. There wasn’t any erratic, drunken behavior off-screen… He seemed convinced dementia was his problem.”

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David Cassidy performs with band member and close friend Craig J. Snider in 2015.  (A&E Network)

Cameras followed Cassidy as he underwent several exams to find out what was causing his memory loss, which would impact him while performing. Marks revealed that Cassidy, who had witnessed his mother Evelyn Ward’s health deteriorate until she passed away at age 89 in 2012, feared he too was faced with the same illness.

Cassidy had also worked with organizations to educate the public about Alzheimer’s disease and believed the documentary would further shed some light on the condition.

“The doctors wanted to do more tests,” said Marks. “They did see some signs that there could be an issue, but they weren’t comfortable issuing anything, like a diagnosis. So I think David came out of that appointment… feeling hopeful that maybe it wasn’t as bad as he feared or maybe it could be dealt with.

"Was he hiding the truth artfully or lying to himself or in denial about what was really wrong with him? That is something I don’t know. We never really had a chance to talk about that. It’s a bit of a mystery.”

Cassidy also faced another struggle: recollecting painful memories of his father, actor Jack Cassidy. The famous patriarch passed away suddenly in 1976 at age 49 in a fire that swept through his Los Angeles apartment.

The New York Times reported at the time Cassidy’s body was so badly burned that they had to be identified by the medical examiner through dental charts.

“I think in general David wanted to celebrate his father, but he did not want to conceal the truth about that relationship either,” said Marks. “… One minute, he’s talking about how he idolized his father from the first minute he saw him. But at the same time, he wanted to make clear that his father had not been much of a dad. And that he had been an abandoned child.

"I also think there was unfinished business with his dad. And part of what he was doing with those [new] songs was saying, ‘I couldn’t have that final conversation with my father, we couldn’t hash it all out. But what I can do is offer this warts and all tribute to him.”

Jack Cassidy's tragic death would haunt his son David for the rest of his life.

Cassidy noted that as his career skyrocketed at such a young age Jack, who never achieved the same kind of fame, was reportedly jealous of his son’s success and criticized him.

During filming, Cassidy also described how he struggled over the years to live up to his squeaky-clean image and reportedly didn’t get the support from his father that could have helped him cope.

Cassidy, eager to shed his squeaky-clean image, attempted to transition into rock star status by posing nude for the cover of 1972’s Rolling Stone.

After “The Partridge Family” came to an end in 1974, the star would later be faced with substance abuse. Cassidy had been charged with driving under the influence on three separate occasions between November 2010 and January 2014 before entering rehab.

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David recording his final EP “Songs My Father Taught Me: The Last Sessions” in September 2017.  (A&E Network)

“He was one of the biggest stars in the world for four years,” explained Marks. “He had an entourage. Couldn’t go out in public. He had to hide just to leave his concerts. And then for that extraordinary level of fame to just disappear.

“I just think that while [fame] is kind of a fairy tale… it’s almost a little bit like you're standing in the middle of a forest fire. And you burn up. I just think that’s what happened to him.

"And I think he also had a legacy of alcoholism in his family. And it’s not uncommon for people with that level of scrutiny and that much stress and pressure in their lives to turn to alcohol as a way to numb it all.”

While Cassidy would later find out he had liver disease, Marks insisted he was actually relieved by the diagnosis but was also shocked by the news.

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A young David Cassidy performs at Melbourne Cricket Grounds in Australia in 1974 in an archival photo which airs as part of A&E’s Biography Presents: "David Cassidy: The Last Session" premiering Monday, June 11 at 9PM ET/PT.  (Henry Diltz/A&E Network)

“I do really think he was caught off-guard in some way by what happened to him,” said Marks. “He was legitimately terrified of dementia. That I’m convinced of. His experience with his mother was traumatic. So I think he imagined that he was going to be in the same boat she was in and really didn’t know what to do about it.

“But I think this other thing that was hidden from all of us, and perhaps hidden from himself, was a revelation to him… And he was relieved… He was relieved in some ways that his problem was something he can deal with by choice and wasn’t just his brain deteriorating. I think that was an enormous liberation for him.”

“David Cassidy: The Last Session” airs Monday at 9.pm. on A&E.