Parkinson's Found More Often In Men Than In Women

Studies Confirm Men At Higher Risk

A review of multiple studies appears to confirm that men face a much higher chance of developing Parkinson's disease compared to women, according to a new report in the Journal of Neurology, Neurosurgery and Psychiatry.

"This has been something that everyone has assumed for a while, but whenever you stand up and say it someone will say, 'There's no proof of that," says Dr. Fred Wooten, chairman of the neurology department at the University of Virginia School of Medicine in Charlottesville.

"'Well, now we've got the closest thing there is to proof," he says. 

According to Dr. Wooten, the most likely culprit for a 'gender gap' for Parkinson's may be the heightened vulnerability of male offspring to a genetic mutation passed down by their mothers.

Parkinson's Symptoms Are Progressive

Parkinson's disease involves the steady loss of brain cells that produce dopamine, a chemical messenger essential to proper motor function.

As the levels of dopamine decrease, chemical messages between brain cells "misfire," triggering symptoms such as tremors, loss of balance, rigidity, and other abnormalities.

Parkinson's is progressive and has no cure, although the use of certain drugs can ease its symptoms. The National Parkinson's Foundation estimates that 1.5 million US adults are affected with the disease.

Dr. Wooten says the observation that Parkinson's affects more men than women has a long history.

"In the original description in 1807 by James Parkinson, he describes five men [and no women]," Dr. Wooten points out. "So from the absolute beginning of the descriptions there's always been the sense that there are more men than women affected."

Still, no one had pulled together the data to prove this gender bias until now.

Experts Continue To Look For Reasons

In their study, Dr. Wooten's team examined data from seven population-based studies conducted in the US, China, and four European countries since 1980.

They report that, worldwide, males face a 50 percent higher risk of developing Parkinson's than do females.

Uncovering the reasons behind this trend may be a tougher problem, however. There is "weak" evidence that something about the male lifestyle - increased exposure to pesticides, for example, or a higher incidence of head injury - might account for men's higher incidence of Parkinson's disease, Dr. Wooten says.

A second theory holds that estrogen might help protect women against neurological illnesses such as Parkinson's.

"There's a great deal of evidence, both from test-tube studies as well as some animal studies, that estrogen has a neuroprotective role and that higher levels of estrogen in women might somehow protect them from this particular neurodegenerative disease," Dr. Wooten explains.

But more intriguing theories focus on the genetics of men - and their mothers.

Genetic mutations specific to Parkinson's have recently been located on the X chromosome.

"Genetic abnormalities on the X chromosome tend to affect men more than women," Dr. Wooten says, "because men have only one X chromosome and women have two," leaving men less leeway whenever X-chromosome genes are expressed.

Men might also be more vulnerable to a Parkinson's-linked mutation of a gene found in what is known as mitochondrial DNA. Mitochondrial DNA is a relatively tiny reservoir of DNA found outside the nucleus, and it is only passed via the mother to her offspring.

For reasons that remain unclear, the sons of women who carry this mitochondrial abnormality could be at especially high risk of developing the disease.

"We are about to publish another large, more definitive [study], showing that there's an unexpected excess of maternal transmission in Parkinson's disease," Dr. Wooten explains.

"If you look at a group of patients affected with Parkinson's disease, and you ask how many of them have an affected mother and how many of them have an affected father, the incidence of affected mothers is higher," he says.

Parkinson's is not the only brain disease more likely to hit men than women.

"Diseases like amyotrophic lateral sclerosis - ALS, or Lou Gehrig's disease - are more common in men," says Dr. Jay Van Gerpen, director of the Movement Disorder Clinic, part of the Ochsner Clinic in New Orleans.

Dr. Van Gerpen also notes tremor-type illnesses similar to Parkinson's appear to affect more men than women.

Can anything reduce the risk for Parkinson's? Dr. Van Gerpen says one lifestyle factors known to decrease disease risk at this point in time is coffee-drinking.

A cup or two of coffee per day might be beneficial, Dr. Van Gerpen says.

"There have been a number of studies that have shown this - that patients who consume coffee are less likely to get Parkinson's disease. As a coffee drinker myself, that's good news."

Always consult your physician for more information. 

May 2004

Parkinson's Found More Often In Men Than In Women

Parkinson's Symptoms Are Progressive

Experts Continue To Look For Reasons

Parkinson's Disease FAQ

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Parkinson's Disease FAQ

According to the Parkinson's Disease Foundation, as many as 1 million Americans suffer from Parkinson's disease. While about 15 percent of Parkinson's patients are diagnosed before the age of 40, incidence increases with age.

The cause is unknown, and although there is presently no cure, there are many treatment options such as medication and surgery to manage the symptoms.

Parkinson's disease belongs to a group of conditions called movement disorders. It is both chronic, meaning it persists over a long period of time, and progressive, meaning its symptoms grow worse over time.

The Parkinson's Disease Foundation states that the disease occurs when a group of brain cells, responsible for the production of a chemical called dopamine, begin to malfunction and eventually die.

Dopamine is a neurotransmitter, or chemical messenger, that transports signals to the parts of the brain that control movement initiation and coordination.

When Parkinson's disease occurs, for unexplained reasons, these cells begin to die at a faster rate and the amount of dopamine produced in the brain decreases.

The four primary symptoms are:

• tremor of the hands, arms, legs, jaw, and face
  
  
• rigidity or stiffness of the limbs and trunk
  
  
• bradykinesia or slowness of movement
  
  
• postural instability or impaired balance and coordination
  

The following is a list of secondary symptoms of Parkinson's disease:

• speech changes
  
  
• loss of facial expression
  
  
• micrographia (small, cramped handwriting)
  
  
• difficulty swallowing
  
  
• drooling
  
  
• pain
  
  
• dementia or confusion
  
  
• sleep disturbances
  
  
• constipation
  
  
• skin problems
  
  
• depression
  
  
• fear or anxiety
  
  
• memory difficulties and slowed thinking
  
  
• sexual dysfunction
  
  
• urinary problems
  
  
• fatigue and aching
  
  
• loss of energy
  
  

Always consult your physician for more information. 

Online Resources

Centers for Disease Control and Prevention (CDC)

Healthfinder, US Department of Health and Human Services (HHS)

National Institute of Neurological Disorders and Stroke

National Institutes of Health (NIH)

National Library of Medicine

National Parkinson's Foundation