Its true there's no cure but the pallaiative care can be good. I find the Levodopa + ropinerole (dopamne agonist) help me physically whilst counselling helps me get a positive attitude. I have hard times but good too.
I have had it 6 years , how long has your mom had it , whats her drug regime, and how is it affecting her physically and mentally.
A book i'd recoomend is 'SO I've got parkinsons' by Terry Rummins ... its shortish , simple and makes a lot of good points about PD ... its written when she had had PD for about 6 yrs i think.