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peak dose dyskinesias. Newer, longer-acting agonists
may have an even more dramatic effect. As discussed in
Questions 30 and 42, PD cannot be cured, but its rate
of progression may be slowed. Dopamine agonists such
as Mirapex and Requip, discussed in Part 3 (Questions
23 30), and co-enzyme Q10 in doses of 1200 mg per
day may slow the rate of progression of PD.
The Beginning. Parkinson disease (PD) was described by
James Parkinson in 1817 at the start of the Industrial
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Revolution. Is PD an outgrowth of the Industrial Revo-
lution? Is it the result of a toxic by-product of the Indus-
trial Revolution one that poisons the internal
environment of the brain? Or is PD a result of the
increased lifespan that is itself a by-product of the Indus-
trial Revolution? A perverse bargain where we live
longer only to develop diseases not known in the past?
Genes and Lewy bodies. In 1913, a pathologist named
Lewy discovered within certain nerve cells of people
with PD, a round structure, or body, the Lewy body.
Lewy correctly assumed the body was a marker, a tomb-
stone, of cell death. In 1996, 83 years after Lewy, doctors
found that Lewy bodies contain a protein called alpha-
synuclein that is coded by a gene on Chromosome 4.
They subsequently found that Lewy bodies contain at
least two other proteins, parkin and ubiquitin, that are
coded by other genes on other chromosomes. The genes
are blueprints, sets of instructions, that enable each cell
to make the proteins it needs to carry on its specific
activity. How genes are translated into proteins, how the
proteins are assembled, how they re transported to where
they re needed, and how they re removed after they ve
outlived their need, is under study. This will result in
new insights into how cells live or die, and will offer us a
chance to halt or cure PD.
MPTP, metals, and viruses. Drugs such as MPTP, met-
als such as manganese, brain injuries such as in boxing,
and viruses such as those causing encephalitis, can
cause brain cells to die, resulting in PD. But the dying
cells do not contain Lewy bodies. Thus it s reasoned
the process that kills them is different from that of
PD. Whether you die from a bullet, an infection, or a
poison, you re equally as dead; but in each case the
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process of dying is different. And so are the ways of
preventing it. Lewy bodies may contain the secrets of
PD, and their importance may transcend PD. In
examining the brains of people after death, for each
person with PD, there are 10 with Lewy bodies with-
out PD. Are they at risk for PD? Presently PD affects
1 percent of all people age 60 years or older. If we live
longer, will PD affect 10% of all people over age 60?
The Substantia nigra. In 1919, 102 years after Parkin-
son, and 6 years after Lewy, Tretiakoff, a pathologist,
discovered a loss of pigmented nerve cells in a region
of the brain called the substantia nigra. This is where
PD starts. Lewy had marked the dying cells but he
hadn t realized they were grouped together. Although
the loss of pigment is obvious to the naked eye, and
although many pathologists had studied PD, none had
seen what Tretiakoff saw. There are 400,000 cells in
the substantia nigra. They start to pigment after birth
and are fully pigmented at age 18. The pigment is a nor-
mal product of cell metabolism. The pigment doesn t
cause the cell to die, rather the loss of pigment is a
marker of its impending death. The symptoms of PD
follow the loss of cells. When you lose 240,000 cells,
60% of the cells in your substantia nigra, you develop
symptoms. It s said that all of us (with or without PD)
lose 2000 nigra cells each year. And, if we lived the
Biblical four score and forty years, or 120 years old,
we would all have PD. At some point, and it s not
known when or why, the cell loss accelerates: with per-
haps 4,000 to as many as 10,000 or more nigra cells
dying each year.
Discovering when PD starts, before 240,000 cells have
died, and finding out why, will dramatically change our
treatment approaches. The cells could die because of
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an inherited defect, a flaw in its blueprints. Or the cells
could die because of an internally produced chemical, a
naturally occurring free radical. Or the cells could die
because of contact with an external chemical, an envi-
ronmental toxin, one that breeched the cell s defenses.
Depending on the cause, appropriate treatments could
be devised to counteract it.
Parkinson-like diseases. PD-like diseases resemble PD
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