Let's take age itself as the starting point, because there are some nuances that are not generally known. In line with popular perceptions, about 90% of people with the illness are over 60 years old.
This is true even if you consider the age at which the symptoms first appear. Not even 10% of cases are diagnosed in adults under age 40. Most of the fresh diagnoses are in those above age 60.
However, that's not the whole story.
Among those over 60, the risk goes up from age 60 to age 75. After that, it drops sharply. In other words, someone who is 85 years old is less likely to get Parkinson's disease than someone who is 70, statistically speaking. This may seem surprising to most people.
Let's look at it from another angle. The above statistics apply to those who have been diagnosed with the illness. If we take what is called Parkinsonism (meaning, symptoms of Parkinson's that have other causes, or symptoms that may develop into the illness itself) into account, fully 15% of those between 60 and 75 have it. And between 75 and 84 years of age, an amazing 30% have the illness.
At the moment, around 3% of the population over age 65 is affected by the disease. But this percentage is estimated to double over the next four decades.
Age obviously has an impact on the disease. What other factors exist?
Gender is evidently another one. It is estimated that men have about twice as much risk of developing Parkinson's as women. This applies to every age group.
Researchers theorize that the female hormone estrogen is responsible for the lower incidence of the disease among women. There are two facts to support this view.
The first is that women who have undergone hysterectomies have a somewhat higher risk of developing Parkinson's disease. Secondly, women who are on hormone replacement therapies tend to have a lower incidence of the condition. These facts seem to imply that estrogen does play a role in preventing Parkinson's.
The illness also seems to progress faster in men than in women. In terms of symptoms, women tend to be prone to disturbances in their gait, while men are more at risk of tremors and rigidity.
Heredity appears to play a role in the disease. Someone whose siblings who have developed Parkinson's disease before the age 40 is at greater risk of falling victim to the illness. However, if the siblings develop the disease only in later years, heredity does not seem to play a prominent role.
There are differences among races in the incidence of Parkinson's, so ethnicity does appear to play a role. Caucasians are at greater risk than Asian Americans or African Americans. Some research indicates that although races other than Caucasians have lower overall risk, they may carry a higher risk of other types of Parkinsonism which involves problems with the thinking process.
Apart from the above, some evidence suggests that caffeine might offer protection against this disease, to an extent. Drinking coffee regularly, it seems, is a useful preventive measure.
As can be seen, some factors do seem to create a higher risk of a person developing Parkinson's disease. Researchers are digging deep for more clues that may one day lead to a full understanding of this condition.
