A new study concludes that for some
people, having had their appendix removed decades earlier reduced the risk of
developing Parkinson's disease by almost 20 percent.
The appendix is the barely visible, tail-like
appendage to the bottom left of this diagram.
Parkinson's disease is a long-term
degenerative condition that affects the central nervous system.
In the United States, medical
professionals tend to diagnose around 60,000 new cases each year.
Symptoms include tremor, slow
movement, stiff muscles, and changes in speech.
Because Parkinson's almost
exclusively appears in older adults, as the population ages, the number of
cases is also set to rise.
In fact, by 2030, there may be as
many as 1.2 million people in the U.S. with Parkinson's disease.
To date, treatments only help manage the symptoms; there is no cure.
Because of its growing prevalence,
it is more important than ever to discover clues about how and why it develops
in certain people.
A recent study dipped into the data
of almost 1.6 million Swedish adults and followed them for an average of 52
years. The findings, published this week in the journal Science, add a new and intriguing insight into
Parkinson's.
Led by Bryan Killinger, the
researchers focused on the appendix. This might seem like an odd starting
point, but there is solid reasoning behind it.
Why the
appendix?
In many Parkinson's cases,
gastrointestinal symptoms present themselves long before neurological symptoms
appear. In some cases, these symptoms can precede motor symptoms by 20 years.
Moreover, alpha-synuclein is present
in the nerves of the digestive system; this protein is the major component of
Lewy bodies — clumps of protein in the brain — that are a hallmark of
Parkinson's.
Alpha-synuclein plays a significant
role in the pathology of the disease, and its presence in the
gut may account for the early digestive symptoms.
Researchers believe that misfolded
alpha-synuclein in the gut might spread from cell to cell before eventually
reaching the brain. There is evidence that
once the protein has become misfolded, it causes a chain reaction, spreading
its new, misshapen form to its neighbors.
This is similar to how prion
diseases such as Creutzfeldt-Jakob disease can
spread throughout the body.
As with other parts of the
gastrointestinal system, the appendix also contains high levels of
alpha-synuclein, making it an appealing target to study.
The team's
analysis showed that an appendectomy reduced the risk of developing Parkinson's
by 19.3 percent.
More
surprises in the data
When they delved deeper into the
details, they found that the effect was strongest for people living in rural
areas. This infers that there is some interaction with the environment. The
authors theorize that this might be connected to pesticides, which have been linked to
the development of Parkinson's disease.
In a further analysis on 849 people
with Parkinson's, they found that those who had undergone an appendectomy
decades earlier developed Parkinson's an average of 3.6 years later. The
authors write:
"The presence of pathogenic
alpha-synuclein species in the appendix indicates a mechanism by which the
appendix may contribute to, and possibly trigger, the development of
[Parkinson's disease]."
To investigate further, the
scientists examined the appendixes of healthy participants. As expected, within
the neurons and mucous membranes of the appendix, they found forms of
alpha-synuclein that are prone to aggregate.
They also reveal that this form of
the protein was more prevalent in the appendixes of people with Parkinson's
disease.
The authors of the study believe
that targeting the buildup of alpha-synuclein in the appendix may be an
exciting new avenue of research. With the worrying projected figures of
Parkinson's disease, new research into this is likely to follow swiftly.
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