What Causes Parkinson's Disease?

In short, we don't know yet. There are many theories about the possible causes of Parkinson's, but none of them have been proven yet.

Most people researching the disease agree that there are probably multiple factors that contribute to someone getting Parkinson's.

A lot of people ask about things like heredity, pesticides, head trauma (as in Muhammed Ali's case), and aging, and whether or not these could be possible causes for Parkinson's.

First of all, let's start with what the researchers do know. They do know that Parkinson's does not result from something that a person has done, from his or her diet, or from stress.

Head trauma is also something that researchers know rarely causes Parkinson's. Some studies have found though, that those who have experienced a head injury are four times more likely to develop PD than those who have never suffered a head injury.

The same studies showed that the risk of PD increases by 8 times for people who required hospitalization for head trauma and 11 times for those people who had a loss of consciousness, skull fracture, prolonged memory loss or more complications.

Even though the association is strong, researchers warn that this doesn't mean that head injuries cause PD. The same is true for tumours.

Researchers also know that heredity does not play a major role in causing the disease except in familial Parkinson's disease (families with many members having the disease over several generations).

Basically, if you have a family member who has Parkinson's, it is most likely a coincidence if you happen to develop the disease as well (because the disease is so common).

Researchers have discovered that it is possible that some people have a genetic susceptibility to developing Parkinson's disease. What that means is that for example, some people just don't have the ability to deal with toxic materials, so when they are exposed to them, they may develop PD.

Speaking of toxic materials, this is an area in which researchers searching for possible causes of Parkinson's are currently very interested in.

Researchers have suggested that Parkinson's might result from a toxin that gradually builds up in the brain, causing the degeneration of certain nerve cells in that small part of the brain we talked about earlier called the substantia nigra.

This toxin could build up either through exposure to an environmental toxin or as a by-product of a process of the brain. It could also be possible that people get the disease from exposure to a toxin early in life, combined with factors related to aging.

Unfortunately, there still is no firm evidence that environmental toxic materials such as industrial pollutants, herbicides, and pesticides may cause Parkinson's. Researchers will have to continue to work on this one.

Finally, in regards to aging, there is evidence that the number of nerve cells in the substantia nigra decreases as a natural part of aging. Maybe Parkinson's is related to aging then? But what about all those people who are in their 50's, 40's or younger with Parkinson's?

Researchers have considered that maybe there is some kind of accelerated aging process taking place in the brains of people with Parkinson's, but what the process is or how it starts is still unclear.