The 66-year-old actor is widely known for his starring role as Keith Partridge on the 1970s series The Partridge Family

David Cassidy Reveals He Is Battling Dementia: 'A Part of Me Always Knew This Was Coming'

David Cassidy is battling dementia.

The 66-year-old actor, widely known for his starring role as Keith Partridge on the 1970s series The Partridge Family, reveals to PEOPLE that he is fighting the memory loss disease.

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Cassidy, who watched his grandfather battle the disease and witnessed his mother “disappear” into dementia until she died at age 89, tells PEOPLE of his diagnosis: “I was in denial, but a part of me always knew this was coming.”

Of his mother’s struggles, Cassidy recalls: “In the end, the only way I knew she recognized me is with one single tear that would drop from her eye every time I walked into the room. … I feared I would end up that way.”

Now that he’s come to terms with his condition, Cassidy has made the decision to stop touring as a musician to concentrate on his health and happiness. “I want to focus on what I am, who I am and how I’ve been without any distractions,” he says. “I want to love. I want to enjoy life.”

Cassidy’s revelation follows a roller coaster of personal ups and downs that the actor has faced in the past decade, including a show in Agoura Hills, California, this past weekend where Cassidy repeatedly struggled to remember lyrics to songs he had been singing for nearly 50 years.

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The ’70s teen heartthrob has also battled substance abuse issues, including a stint in rehab in 2014.

For more on how David Cassidy is coping with his dementia diagnosis, pick up this week’s issue of PEOPLE, on newsstands Friday

Cassidy, who received an Emmy nomination for his appearance on Police Story in 1978, was most recently seen on TV in a 2013 episode of CSI: Crime Scene Investigation.