Progression of Parkinson's?

Parkinson's disease affects how you move.
An early sign is a slight trembling in one hand. Over time, you start doing things more and more slowly as your muscles become stiff. You may lose your balance more easily

Some people with Parkinson's live for years with mild symptoms that can be annoying but don't need treatment.
But if your symptoms get worse, there are treatments that can help.
Key points for people with Parkinson's disease
Parkinson's disease usually starts in people who are over 60.
The main symptoms are shaking, stiff muscles, slow movements and poor balance. But you may not get all of these.
It can be hard for doctors to diagnose Parkinson's disease. Other conditions have similar symptoms.
Keeping track of your symptoms is important. If you can describe your symptoms clearly, this will help your doctor find the right treatment for you.
How your brain helps you move
To understand what happens when you have Parkinson's disease and how it can be treated, it's useful to know something about how your brain works.
Cells deep inside your brain control how and when you move.[1]
These brain cells make dopamine. Dopamine is a neurotransmitter, a type of chemical that helps messages travel between nerve cells, including your brain cells.
Brain cells need dopamine to send messages to other parts of your brain, and to nerves and muscles throughout your body.
Messages deep inside your brain help you move smoothly and do the right thing at the right time. For example, they stop you tripping at the kerb as you step into a road. And they help you move your fingers to tie your shoelaces.
What happens in Parkinson's disease?
Parkinson's disease happens when the brain cells that make dopamine die or don't work properly. Doctors don't know why this happens.[2] With less dopamine, brain cells in some parts of your brain don't send messages properly. This means you can't control your movements in the usual way. The amount of dopamine in your brain has to drop by 80 percent for the signs of Parkinson's disease to show.
Why me?
Doctors don't know why some people get Parkinson's disease and others don't. But there are some things that increase your chances of getting it. Doctors call these risk factors.
If you have a risk factor, this simply means you have a higher chance of getting the disease than someone without the risk factor. It doesn't mean that you will definitely get it.
The main risk factor for Parkinson's disease is getting older.[3]
To learn more, see Risk factors for Parkinson's disease.
References
Pearce JM. Parkinson's disease and its management. Oxford Medical, London, UK; 1992.
Goldsmith C. Parkinson's disease. American Journal of Nursing. 1999; 99: 46-47.
Ben-Shlomo Y. How far are we in understanding the cause of Parkinson's disease? Journal of Neurology, Neurosurgery and Psychiatry. 1996; 61: 4-16.
© BMJ Publishing Group Limited ("BMJ Group") 2009