(I) Parkinson’s disease results from degeneration of
cells in the basal ganglia, a part of the brain involved in
initiating movement. (II) The three layers of membranes
that surround the brain and spinal cord become
inflamed, usually as a result of infection. (III) Normally,
the cells produce a neurotransmitter called dopamine,
which helps to coordinate muscle activity. (IV) In
Parkinson’s disease, these cells produce much less
dopamine and the signals to the muscles become slow
and faulty. (V) The disease is most common in older
people, but may occur in young adults or, rarely, in
children.