Wondering if my sister has Parkinson's?

My sister has a very stiff and unresponsive look. Kind of mask like. She has just started showing these symptoms for about three months now. It is getting worse. She is going to see a neurologist in about six weeks. She has underactive thyroid problems also. She also has arthritis. Does anyone out there see any connections with parkinson's and diet or enviromental factors or being exposed to radiation as a possible cause of the disease? Thanks!