If this doesn't answer the question, I am sure someone else will attempt to eplain it better:

"Dopamine is a substance known as a neurotransmitter. Neurotransmitters are found the brain and nervous system and are involved in transmitting messages between nerves. These messages allow the normal functioning of the body. The neurotransmitter dopamine is known to be reduced or absent in the brains of people with Parkinson's disease, and this is thought to be the cause of the disease symptoms.

"When you take levodopa, it is converted into dopamine in the brain. This replaces the lost dopamine and therefore reduces some of the symptoms of the disease.

"Levodopa is also converted into dopamine in the rest of the body, which can cause unwanted side effects such as nausea and palpitations. Carbidopa is used in combination with the levodopa to prevent this happening. Carbidopa is a type of medicine called a dopa-decarboxylase inhibitor. It blocks the conversion of levodopa to dopamine in the body and so prevents these side effects. (Carbidopa cannot pass into the brain and so does not affect the conversion of levodopa to dopamine in the brain.)

"The combination of levodopa and carbidopa is therefore effective in the treatment of Parkinson's disease, while minimising the side effects caused by levodopa on the rest of the body."

Source: NetDoctor.com

Yes, one of the ways a neurologist can tell you have PD is if you try a dose of Sinemet and you respond positively to the medication. If you don't respond to it, then you probably don't have PD. In other words, if you don't say, "Oh my gosh. I feel great." after a dose of Sinemet...hummm. I have heard this reaction from PWPs who experience Sinemet for the first time.

Thank you for this!

bump bump bump

I see that you started this thread in 2007. How has your condition changed since then?

Just last week I was at a support group and was surprised when people introduced themselves that many have had PD about the same length of time that I have, but are much worse off than I am.

Rick.... thanks for the bump. I missed it the first time around and found it very valuable.

Some blessings come with old age! as a late onset PWP, I am fortunate in being a resident in one of several veterans retirement homes in the state of Texas. As such, I am particularly close to the daily habits of several Parkinson's patients here at the facility. Most are late onset but there are several early-onsets among our population.

On behalf of the patients here I think I can affirm prior observations which in substance identified Parkinson's as a multi-cause, multi-symptom, limited treatment with no cure in sight disease. I have been privileged to observe from sunrise to bedtime each day most all of these factors. Stress, diet, exercise, attitude etc.and their impact on various bodily functions.

As you know from private conversations with me I have been hospitalized three times during the past year all of which are Parkinson's related. These included a diagnosis of septicemia, a bowel blockage and Parkinson's periodic paralysis of my right arm. Presently I have have had to deal with three episodes of urinary tract infection. Fellow patients have also contracted respiratory ailments skin rashes, pneumonia, etc.

When the soon-to-be published book is completed we plan on continuing our active roles including studies dealing with the material provided in this thread. Thanks again for the revival.