Which of the following diseases is related to the nervous system?

Parkinson's disease is directly related to the nervous system because it is considered a neurodegenerative disorder that primarily affects the motor system. It involves the progressive degeneration of neurons in specific areas of the brain, particularly the substantia nigra, which leads to a deficiency of dopamine, a neurotransmitter crucial for coordinating smooth and controlled movements. This deficiency manifests as the characteristic symptoms of Parkinson's, including tremors, rigidity, bradykinesia (slowness of movement), and postural instability. Understanding this connection highlights the importance of the nervous system in regulating voluntary movements and the impact that neurological diseases can have on a person's overall function and quality of life.

The other options pertain to different bodily systems: congestive heart failure relates to the cardiovascular system; hypertension also affects the circulatory system; and diabetes generally involves the endocrine system, particularly regarding insulin and blood glucose regulation. Therefore, they do not share the specific involvement with the nervous system that Parkinson's disease does.