Currently there is no cure for Parkinson's disease a brain disorder that affects movement. Parkinson's symptoms begin gradually and get worse over time. Usually it starts with a barely noticeable tremor in just one hand. As the disease progresses patients may experience shaking stiffness and difficulty walking and talking. These symptoms result from the loss of neurons that produce dopamine a chemical messenger involved in sending messages to the part of the brain that controls movement and coordination. Dopamine replacement therapy (DRT) which aims to replenish dopamine levels in the brain is considered the most effective treatment for Parkinson's disease.