Etiology of Parkinsons disease

Primary or idiopathic
Secondary :
Environmental – toxins like MPTP, carbon monooxide, manganese
Repeated head injuries as in boxers
Free Radicals – there is a increase level of free radicals in post-mortem brain sections
Aging – age related decline in dopamine production
Genetic – possible, no single gene identified, mutation in the gene coding synuclein protein leading to formation of lewy bodies
Drug induced like antipsychotic drugs, reserpine, metoclopramide etc