It is done only to slow the progression of the disease, provide symptomatic relief of motor and non-motor symptoms, and prevent motor fluctuations and dyskinesia. Ali Samii et al state: “Vitamin E, selegiline, and coenzyme Q10 have been studied as potential neuroprotective agents to slow disease progression” (1788). These agents act in the early stages of the disease and can also alleviate the effect of motor symptoms. Dopamine agonists and levodopa are also drugs used in the treatment of Parkinson's disease to maintain stable dopamine concentrations. With younger, healthier patients, treatment begins with dopamine agonists because they rarely cause dyskinesia and is sufficient to control Parkinsonian symptoms for the first two years. In older people, levodopa is the first step of treatment instead of dopamine agonists because, as Kalia and Lang state, "dopamine agonists are more commonly associated with hallucinations and are therefore usually not prescribed to older patients, especially to those with cognitive impairment" ( 906). However, levodopa leads to motor complications in long-term use, dyskinesia, motor fluctuations and nocturnal awakenings, due to the short half-life of levodopa. Therefore, dopamine agonist is used with levodopa to increase the effectiveness of levodopa and reduce downtime..