USA TODAY | What a dementia diagnosis may mean for 'Partridge Family' star David Cassidy USA TODAY "Dementia is an umbrella term," Oh said adding that information on what form of Dementia Cassidy has hasn't been released. "If you are diagnosed with dementia, he could have Alzheimer's, or he could have dementia from a small stroke like vascular ... Why David Cassidy's dementia caused him to fall off the stage and forget lyrics at the young age of 66 David Cassidy Has Dementia: Here's What That Means David Cassidy, dementia and his tragic family history |