Many an aging person has trembling hands--a sure sign, in their
minds, of the onslaught of dreaded Parkinson's disease or
embarrassing unsteadiness of old age.

Both suspicions may well be unwarranted. Instead, the tremors could
be symptoms of what's known as essential tremor (ET), a neurological
condition suffered by about five million Americans, mainly over age
60. It is not deadly or contagious, but it sometimes worsens with the
years. It typically is an inherited disorder.

Essential tremor, physicians say, is thought to be caused by
a "dominant gene." That means all of the children of a person with ET
have a 50 percent chance of inheriting the gene--not half the
children, but each with his or her own 50 percent chance. But even
the child of a patient with severe ET who inherits the gene may have
a very mild disorder.

Many people associate tremors with Parkinson's disease, a well-known
degenerative disorder. Essential tremor and Parkinson's, however, are
not linked in any way. No studies have shown that essential tremor
increases your risk of getting Parkinson's, according to the
Essential Tremor Foundation.

Also, the two differ in these ways: Essential tremor of the hands
occurs usually when the hands are in use. Tremor from Parkinson's is
most common when the hands are at rest--say, in your lap.

Essential tremor causes no other health problems. Parkinson's, on the
other hand, is associated with stooped posture, rigid limbs, slow
movement, speech problems, and sometimes memory loss.

Your doctor's decision about treatment depends on how long you've had
it and how much it affects your lifestyle. For many, avoiding
stressful situations and stimulants is the only treatment necessary.
But there are medications that can help. Drugs that affect your
central nervous system are most commonly used.

Luckily for some folks, alcohol works. One man with essential tremor
said: "I keep a small flask with me when I'm at a meeting and have to
give a speech. I take a few sips a little while before I go 'on,' and
my tremors subside enough so that I no longer find them distracting
or embarrassing."

Beta blockers, normally used to treat high blood pressure, often
work, as does Primidone, the antiseizure drug. Tranquilizers are
sometimes prescribed, but medication in general provides relief for
only about half the sufferers.

Then there's surgery. For that very small number of people whose
tremors are disabling, there's a procedure for affecting a tiny part
of your thalamus. It's a message center deep in the brain.

Dianne Zabel lived with essential tremor most of her adult life
before she found out her nerve disorder was essential tremor. Ms.
Zabel is an elementary-school teacher in Melbourne, Florida. Her
tremor became so severe that in 1999, she underwent a procedure
called deep brain stimulation. A Mayo Clinic neurosurgeon put tiny
wire electrodes in her brain and attached them to a small battery-
powered device implanted In her chest. In a week her tremors ceased,
but essential tremor rarely becomes so severe as to necessitate this
treatment.

Thus, shakiness that causes the clatter of a cup in its saucer (or
the awkward lines in a once-steady or graceful signature) is not just
a sign of getting old. Instead, there's a fair chance you are touched
by essential tremor.

Try holding a sheet of paper in your hand and you probably will see
your own hand tremble slightly, even if you don't have essential
tremor. The reason is that your heartbeats and breathing have a
ripple effect on the muscles of your body. Usually the trembles are
very mild, unless you've guzzled several cups of coffee.

But for those with essential tremor, the trembles are different,
continuing, and more noticeable. The use of the term "essential"
means it is not linked to other diseases. One test commonly used to
identify essential tremor is to have the patient draw a series of
narrow concentric circles on a piece of paper starting at the center
and keeping lines as regular as possible while the circle enlarges.

Try it yourself. If the lines are wavy and shaky the farther out the
circle is enlarged, check with your physician. You may be among the
five million people with essential tremor.

The National Institutes of Health has just opened a new Essential
Tremor Centralized Brain Repository at Columbia University, a major
step toward better treatment and, eventually. a cure for ET. Now
doctors will be able to study what happens to the brains of people
with essential tremor.