Final answer:
Parkinson's disease is a neurodegenerative disorder with no cure. Treatments focus on increasing dopamine levels in the brain. However, L-DOPA treatment can become less effective over time and can cause side effects.
Step-by-step explanation:
Parkinson's disease is a neurodegenerative disorder caused by the death of neurons that cannot be replaced. There is no known cure for the disease, but current treatments focus on increasing dopamine levels in the brain to alleviate symptoms. The most common method is by administering L-DOPA, which is converted into dopamine by the remaining neurons in the substantia nigra pars compacta. However, over time, patients become less responsive to L-DOPA treatment and it can also cause increased dopamine levels in other parts of the brain, leading to negative side effects.