I am not a doctor, but was asked to explain in simple terms that patients could understand and grasp why Parkinson's occurs.
There are two main neurotransmitters, and I'm not talking about science fiction or a new fangled radio that tunes into your brain. Serotonin and dopamine are both neurotransmitters and work together. All this technical medical jargon is not easy to understand, and having difficulty myself in comprehending, I hope I've managed to explain in a simple way so that you too know how to answer difficult questions when thrown at you unexpectedly.
Serotonin: an inhibitory neurotransmitter responsible for mood, relieving anxiety and improving sleep. It is mostly found in regulating intestinal movements.
Dopamine: an excitatory neurotransmitter in the mid-brain area called the substantia nigra is responsible for motor control, energy, generating motivation, focus, concentration and memory. There are several diseases of the nervous system where the dopamine system does not function properly, one of which of course, is Parkinson's.
When there is an imbalance in the neurotransmitters, the deficiency needs to be made up by taking medication. The imbalance effects one's lifestyle and stress exacerbates this defect. It therefore appears to come down to either chemicals in your environment that have caused this flaw, or people, like myself who are born with an inability to make sufficient amounts of these chemicals, and is therefore not related to environment, but rather to genetics.It would be so much easier to explain if for example one had a simple broken leg, or even a hip replacement. People can generally understand and grasp these types of medical issues, but as soon as you get into the fascinating world of neurology, explanations and symptoms, side effects and treatments are so much more involved. Why does life have to be so complicated?