Europe South Asia Asia Pacific Americas Middle East Africa BBC Homepage World Service Education



Front Page

World

UK

UK Politics

Business

Sci/Tech

Health

Education

Sport

Entertainment

Talking Point
On Air
Feedback
Low Graphics
Help

Wednesday, January 27, 1999 Published at 10:27 GMT


Health

Two types of Parkinson's

The disease usually affects people over 50

There may be two types of Parkinson's disease - one caused by heredity and one caused by environmental factors, according to a study.

Heredity is usually singled out as the main factor behind the disease.

But research has shown that environment is the likely cause of Parkinson's disease in most patients over the age of 50.

The researchers suggest that there could be two separate conditions - one caused by genetic factors that starts before 50, and another caused by environmental factors that starts after.

Degenerative disease

The research looked at almost 20,000 twins who were veterans of World War II.

It was carried out by researchers at the Parkinson's Institute in Sunnyvale, California.

The findings were published in the Journal of the American Medical Association on Wednesday.

Parkinson's disease is a progressive, degenerative brain disease, which slowly reduces the ability of the nerves to control the muscles.

Famous Parkinson's patients include Muhammad Ali, and Michael J. Fox, Enoch Powell and Pope John Paul II.

The potential causes of Parkinson's have been a matter of dispute among scientists for years.

In recent years, research has turned up evidence of specific genetic defects that can cause Parkinson's.

Some scientists have thus suggested that heredity is a principal cause for the condition.

Twins

The California study examined both identical and fraternal sets of twins.


[ image: Muhammed Ali has the degenerative disease]
Muhammed Ali has the degenerative disease
Because identical twins share the exact same genetic profile while fraternal twins are no closer genetically than any other siblings, the researchers had a clear view of how closely the disease is tied to genetic factors.

It found that, in the rare instances of "early onset" Parkinson's striking before the age of 50, both members of each of the identical twin sets in the study came down with the disease, meaning the cause was almost certainly genetic.

But in the "typical" cases of Parkinson's, diagnosed after the age of 50, the study found no statistical difference between identical and fraternal twins. In each case, only about 10% of the twins came down with Parkinson's.

The researchers said this means environmental factors were almost certainly to blame.

Research focus

Dr J. William Langston, president of the Parkinson's Institute, led the research.

He said: "The results appear to be fairly clear-cut. They tell us that in typical Parkinson's disease, occurring over the age of 50, there does not appear to be a genetic component. There was no evidence of a hereditary factor."

Dr Langston said research into the disease could now focus on external factors such as herbicides, pesticides, and other chemicals.

"If it's not inherited, that really points very strongly to something in the environment," Dr Langston said.

"From a scientific angle, we really know where to invest our money in research."

Dr Langston said the results of the study pointed to such a major difference between "early-onset" Parkinson's and the typical form the disease that the two could be entirely separate conditions.

"Our suspicion is that typical Parkinson's disease is environmental in origin, but that 'young-onset' cases belong to a group of genetic disorders.

"I think they are actually going to turn out to be different diseases, albeit look-alikes."



Advanced options | Search tips




Back to top | BBC News Home | BBC Homepage | ©


Health Contents

Background Briefings
Medical notes

Relevant Stories

03 Dec 98 | Health
A brave new dawn for medicine

23 Oct 98 | Medical notes
Parkinson's Disease

18 Nov 98 | Health
Drug suspended after deaths





Internet Links


Parkinson's: Information for patients and professionals

Parkinson's: Support and information

Institute of Neurology


The BBC is not responsible for the content of external internet sites.




In this section

Disability in depth

Spotlight: Bristol inquiry

Antibiotics: A fading wonder

Mental health: An overview

Alternative medicine: A growth industry

The meningitis files

Long-term care: A special report

Aids up close

From cradle to grave

NHS reforms: A guide

NHS Performance 1999

From Special Report
NHS in crisis: Special report

British Medical Association conference '99

Royal College of Nursing conference '99