How To Determine Parkinson's Disease?

Mom has Parkinson I need to know what is the test to determine this. I was told that she could have Lew Body Dementia. Lew Body maybe but no Dementia yet. She is being treated with s Parkinson drug that helps her with walking. But this med is making he feel like here husband is out to kill her. We think maybe he is sad about her condition. He is her prime caregiver but they have alot of family support. She is in and out of hospital.