Jon has an excess of cerebrospinal fluid in his frontal lobe area while Will has a deterioration of neurons in the substantia nigra. What is implied here?

It is implied that Jon has Hydrocephalus and Will has a high risk of developing Parkinson disease and Dyskinesias.

Explanation:

Hydrocephalus is medical condition where there is a build up cerebrospinal fluid in the brain. This occurs as a result of an increase in the production of the fluid or a reduction in its absorption rate. The excess fluid can put too much pressure on the brain, damage the brain tissues and eventually lead to brain damage.

Substantia nigra is a motor nucleus in the mid brain that has an important role of coordinating movement. Cells in the substantia nigra are responsible for releasing important nuerotransmitters that help in movement and coordination.

But when there is a deterioration of the neurons in the substantia nigra, movement, balance, coordination and muscle control will be affected. This could lead to Parkinson disease or Dyskinesias