My wife of 57 yrs has Parkinson's, depression, anxiety and essential tremors. Could she be showing signs of dementia?

 She's had it for over 20yrs. My question is , she is 90% helpless for 3/4 of the day then in mid to late afternoon she comes to life and tries to do things she's not able to do, most times ending in a fall. She usually directs her falls into a chair or on the couch or bed, on a couple occasions she fell on the floor usually when I'm not watching. My concern is if this is a sign of dementia, her mind seems to be fine except when she acts strange long term she can remember her childhood to quite a young age. I've tried to have her tested but she's very stubborn and won't keep Dr appointments. She did have a written cognitive test in the Dr's office about 2yrs ago and scored 21 but don't know what that means. She has a scheduled appointment Dec 3rd with her neurologist would it be advisable to speak to him before the appt?