Final answer:
The patient properly understands the drug therapy for Parkinson's disease by acknowledging the role of the levodopa/carbidopa combination in improving motor function through the increase of dopamine levels in the brain.
Step-by-step explanation:
A patient who is newly diagnosed with Parkinson's disease has expressed understanding of drug therapy for the disease when stating: 'A levodopa/carbidopa combination is used to improve motor function.' This indicates that the patient has grasped that the primary treatment for Parkinson's disease involves increasing dopamine levels in the brain to alleviate motor symptoms. Levodopa (L-DOPA) is a precursor to dopamine that can cross the blood-brain barrier and is converted into dopamine by neurons, compensating for the loss of dopaminergic neurons in the substantia nigra. Carbidopa is often administered with levodopa to inhibit the enzyme that breaks down dopamine, allowing for more effective treatment of symptoms such as tremors, slowed movement, and muscle rigidity.