Former teen idol David Cassidy has revealed he has dementia, after forgetting the words to his own songs during concerts last weekend.

The 66-year-old US singer and former Partridge Family star has said he will stop touring after admitting that he is suffering from the same disease his mother and grandfather had.

"I was in denial, but a part of me always knew this was coming," he told People magazine.

"In the end, the only way I knew she recognised me is with one single tear that would drop from her eye every time I walked into the room," he said of his mother.

"I feared I would end up that way."


Image: David Cassidy performing in 2012

Cassidy appeared to fall off stage and struggled to remember some of his old numbers at small venue gigs in California on Saturday and Sunday.

Video has emerged of Cassidy yelling at one fan to turn off a light that he claimed was blinding him, and hugging his guitar.

At one point, he appeared to fall off the side of a small stage before climbing back up.

Those erratic performances prompted fears among fans that the former heart-throb was drinking again.

Image: Cassidy was seen hugging his guitar between songs

He was arrested three times for drunken driving between 2010 and 2014, and was ordered to go to rehab as part of his sentence in 2014.

A month after his third arrest, his wife, Sue Shifrin-Cassidy, filed for divorce.

He has also fallen on hard times, auctioning his Florida home after filing for bankruptcy in 2015.

Cassidy enjoyed enormous fame as the star of '70s TV show The Partridge Family and also had two UK number ones that decade.

Image: Cassidy in London during his heyday , in 1972

He told the magazine he was stopping touring for the sake of his health: "I want to focus on what I am, who I am and how I've been, without any distractions.

"I want to love. I want to enjoy life," he said.

After his singing career faded, Cassidy changed his focus, appearing in several stage shows, playing an ageing former teen heart-throb in the short-lived 2009 TV comedy Ruby & The Rockits and was a member of the Celebrity Apprentice reality TV show in 2011.

He was most recently seen on TV in a 2013 episode of CSI: Crime Scene Investigation.