Forgive me, please, but I'm a newby here and doing the best I can!

Mom's 85 and has been diagnosed with PD and it's in relatively advanced stages. (Sorry, don't yet know your nomenclature!) Dad is convinced it's because of Prednisone prescribed for rheumotoid arthritis 12 years ago, with the dosage lowered too fast. Psychiatrists and neurologists have tried to convince him it just ain't so, but I'm wondering if there's an ounce of possibility that it could be so. He seems to want to blame someone/something for Mom's disease and Prednisone seems a convenient target.

Thoughts or comments? Many thanks....for your answers and patience!