Which of the following is a common disorder associated with the nervous system?

Parkinson's Disease is a neurodegenerative disorder that specifically affects the nervous system. It is characterized by the progressive degeneration of the neurons that produce dopamine, a neurotransmitter responsible for coordinating smooth and controlled movements. Symptoms of Parkinson's include tremors, stiffness, slowness of movement, and balance issues, all of which are directly related to neurological function.

In contrast, arthritis primarily affects the joints and is not categorized under nervous system disorders. Constipation is associated with digestive issues and the gastrointestinal tract rather than the nervous system. Hypothyroidism, while it can affect neurological functions, is a condition related to the thyroid gland and metabolism rather than a direct disorder of the nervous system itself. Hence, Parkinson's Disease clearly stands out as the most relevant choice in relation to common disorders affecting the nervous system.