 |
Slowly,
but Surely, Progress Is Being Made Against Parkinson's
Latest Efforts Focus on Gene Therapy, a New
Type of Drug, and Caffeine |
By Neil Osterweil
WebMD Medical News
Reviewed by Dr. Charlotte E. Grayson
(Boston) Parkinson's disease (PD) is an illness
that progresses slowly, and so, it seems, have medical
science's efforts at finding ways to fight it. Nonetheless,
researchers at a national meeting of neurologists
here say they are making steady, incremental gains
in their battle against the disease.
One of the notable researchers attending the meeting
Nobel laureate James D. Watson, PhD, who was a co-discoverer
of the structure of DNA in the1950spredicts that
the answer may lie in the field of genetics. "Parkinson's
is not an infectious disease, so it must therefore
have a genetic basis," he tells WebMD.
Indeed, the latest news in the battle against Parkinson's
involves genetics or at least gene therapy. German
researchers speaking at the meeting Tuesday report
that they have devised a gene therapy "cocktail"
that appears to protect critical brain cells in
mice with disabling conditions similar to PD in
humans.
Theirs is one of several new studies describing
promising, but still experimental, treatment approaches
for Parkinson's. Up to 1.5 million Americans suffer
from PD, which causes such symptoms as uncontrolled
trembling, muscle rigidity, and a loss of the ability
to control movement, according to the National Parkinson
Foundation. Over time, people with Parkinson's may
develop trouble walking, talking, or completing
other simple tasks that involve movement.
Just this week, a study was published in the Journal
of the American Medical Association in which Harvard
School of Public Health researchers show that moderate
consumption of caffeine may reduce the risk of developing
PD for men, and possibly for women, too. In the
study of more than 130,000people,the men who consumed
the most caffeine primarily in the form of coffee
were least likely to get PD during their lifetimes.
Women who drank one to three cups of coffee a day
also appeared to be protected from Parkinson's,
but the study seemed to show that drinking more
than three cups a day was too much of a good thing
for women.
This week also saw the release of a study showing
that a new type of drug for
Parkinson's appears to offer benefits over the standard
therapy, levadopa.
Levodopa, marketed as Sinemet or Atmet, is effective
in delaying the progression of PD, but often causes
severe side effects, including involuntary movements
and restlessness. In the study, patients with early
signs of PD who took the new drug Mirapex had a
55% reduced risk of developing movement problems,
compared with patients taking levodopa. The findings
echoed those of a Canadian and European study of
a similar drug Requip that was published earlier
this year.
The gene therapy study focused on cells that produce
a chemical called dopamine. Parkinson's is caused
by the progressive death of nerve cells in the brain
that produce dopamine, which helps the central nervous
system to control bodily movements. The researchers
attempted to deliver to the mice's brains substances
that could protect the dopamine-producing nerve
cells from dying off, and ideally, help them keep
pumping out dopamine as usual.
The gene therapy cocktail they created is composed
of common, harmless cold
viruses that are altered to carry genes for two
such substances: one that may keep the cells from
dying prematurely (through a process known as programmed
cell death), and the other a growth factor that
some studies have shown can keep the brain's dopamine-making
and dopamine-receiving nerve cells in the peak of
health.
"What we have done here is, first, a proof
of principle that a gene therapeutic approach is
working, [and] second of all, that the combination
of a protective therapy, together with a [nerve
cell-restoring] therapy, works," study author
Jörg Schulz, MD, an assistant professor of
neurology at the University of Tubingen in Germany,
tells WebMD.
When they injected the altered viruses into the
brains of mice with the Parkinson's-like disorder,
they found that neither the substance that blocks
cell death nor the growth factor alone was particularly
effective at protecting the brain cells. But the
two in combination did appear to preserve the cells
and their function.
This novel therapy is now limited by the relatively
short time that the genes stay active after injection
the viruses eventually are recognized, and destroyed,
by the body's immune system. In addition, the viruses
cause inflammation and swelling, which also can
cause the protective genes to shut down prematurely.
"The concept of combining treatment approaches
is, I think, an attractive one," says A. Jon
Stoessel, MD, a professor of neurology at the University
of British Columbia in Vancouver, who reviewed the
research for WebMD. "Now the practicality of
it in the long term, the relevance of the mouse
... model to humans, and the ability to salvage
[nerve cells], as well as reduce toxicity, are all
issues that I think are going to have to be addressed."
There's also an additional concern: Because programmed
cell death is a mechanism by which the body rids
itself of harmful or dying cells, interfering with
it could promote the growth of cancers, which are
primarily caused by the unchecked growth of abnormal
cells.
Schulz tells WebMD that the researchers will be
following the mice as they age to monitor them for
any side effects from the gene therapy. At any rate,
it will be several years before the experimental
therapy can make the leap from mice to men and women,
he emphasizes
|
