To enter the reality of the dementia patient is isolating, but I had community support.
With sudden onset of dementia, rule out other health issues, especially UTIs in person of advanced years.
Diagnosis is required to determine which kind of dementia a person has. Alzheimer's is only one kind.
I am not aware of blood tests being used to diagnose Alzheimer's. A special diagnostic memory test is administered verbally by medical specialists.
Some sources and resources on narcissistic personality disorder.