What Causes Parkinson's Disease?

There's been a lot of research into it, but so far, doctors aren't sure of the exact cause of Parkinson's disease. They do know that if you have the illness, the trouble starts in some of your brain cells.

In an area of your brain called the substantia nigra, cells that make the chemical dopamine start to die. Dopamine has an important job to do. It acts like a messenger that tells another area of your brain when you want to move a part of your body.

When the cells that make dopamine start to die, your dopamine level drops. When it gets too low, you can't control your movements as well and you start to get Parkinson's symptoms.

No one knows what triggers the death of those cells. Scientists think it's your genes and environment working off of each other in a way we don't understand.

What Role Do Genes Play?

Your genes are like your body's instruction book. So if you get a change in one of them, it can make your body work in a slightly different way. Sometimes, that means you're more likely to get a certain disease.

There are several genetic mutations that can raise your risk for Parkinson's, each by a little bit. They have a part in about 1 in 10 cases.

If you have one or more of these changes, it doesn't mean you'll get Parkinson's. Some people will, but many won't, and doctors don't know why. It may have to do with other genes or something in your environment.

Can Parents Pass Parkinson's to Their Kids?

They can, but it's rare and only affects a small number of families. About 1 in 100 people with Parkinson's get it this way.

How Does Environment Come Into It?

Your environment is a hard one to pin down. Partly, that's because it covers a lot of ground. It's everything that's not your genes, which could mean where you live, what you eat, chemicals you've come into contact with, and more.

Not only that, but it could take years for the effects from something in your environment to show up. So far, doctors have a lot of clues but no smoking gun. So you could have people who live or work in an area around chemicals tied to Parkinson's, but many of them don't get it.

Some research shows links between Parkinson's and:

• Agent Orange, a chemical used to destroy trees and crops in the Vietnam War.
• Certain chemicals used in farming, such as insecticides, herbicides, and fungicides.
• Some metals and chemicals used in factories, such as manganese, lead, and trichlorethylene (TCE).

These can come into play based on where you live, what you do for work, or if you served in the military. Sometimes, these chemicals seep into well water, so that's one more way they can affect you.

What Raises Someone's Risk for Parkinson's?

It's a complex picture, but you may be more likely to get Parkinson's based on:

Age. Since it mostly affects people 60 and older, your risk goes up as the years go by.

Family history. If your parent, brother, or sister has it, you're a little more likely to get it.

Job. Some types of work, like farming or factory jobs, can cause you to have contact with chemicals linked to Parkinson's.

Race. It shows up more often in white people than other groups.

Serious head injury. If you hit your head hard enough to lose consciousness or forget things as a result of it, you may be more likely to get Parkinson's later in life.

Gender. Men get it more than women. Doctors aren't sure why.

Where you live. People in rural areas seem to get it more often, which may be tied to chemicals used in farming.

What Else Do We Know?

As scientists try to learn what's at the root of Parkinson's, they're looking far and wide to pick up clues where they can.

They've found that people with Parkinson's tend to have something called Lewy bodies in their brain. These are unusual clumps of a protein called alpha- synuclein. The protein itself is normal, but the clumps are not. And they're found in parts of the brain that affect sleep and sense of smell, which could explain some symptoms of Parkinson's not related to movement.

Your gut may also have a part in it, as some of its cells make dopamine, too. Some doctors think that this might be where the earliest signs of Parkinson's show up, but that idea needs more research.

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