When Are Parkinson's Patients a Risk on the Road?
Guidelines Hard to Come By, Experts Say
By Sean Swint
WebMD Medical News
May 8, 2000 -- Laura Liggett is 45 years old and "retired," as she calls
it --  not by choice, but at her doctor's suggestion. Liggett has
Parkinson's disease, a degenerative disorder of the central nervous
system, which interferes with many daily activities, not the least of
which is driving. "Really there's only a small window where I drive, as I
would say, normally," Liggett tells WebMD. "Normally" means without
her reactions being slowed, spastic, or worse. "This one medication I
take makes me really sleepy, and there was at least one time when I
nodded off and I woke up in a different lane than I was in before," says
the Marietta, Ga., resident, who has been on medication for the disease
for 11 years. Although the effects of the disease vary widely from patient
to patient, Liggett's situation is like that of hundreds of thousands of
Parkinson's patients who know that sooner or later, they may have to
decide whether their driving is a hazard to themselves and others.
Parkinson's disease is caused by a gradual deterioration of nerves in a
region of the brain that controls movement. In later stages, there may
be some intellectual deterioration and memory loss. Driving difficulties
can be brought on by many factors, including sleepiness caused by
drugs to treat the disease as well as the physical problems themselves.
"There's been a lot of discussion in the last year or two regarding the
safety of patients with Parkinson's disease in terms of their driving,
particularly as it relates to the use of certain medications that could
perhaps cause them to become very drowsy and suddenly fall asleep,"
Erwin Montgomery, MD, tells WebMD. Montgomery is director of the
movement disorders program at the Cleveland Clinic Foundation in Ohio.
One study looking at the safety of driving for Parkinson's patients was
presented at the annual meeting of the American Academy of Neurology
in San Diego last week. The study's goals, writes researcher Theresa A.
Zesiewicz, MD, were both to evaluate the driving ability of Parkinson's
patients and to determine which variables might serve as predictors of
unsafe driving in these patients. Zesiewicz is with the Parkinson's
Disease and Movement Disorders Center at the University of South
Florida College of Medicine in Tampa. Finding those variables may
prove to be the tricky part, says Abraham Lieberman, MD, medical
director for the National Parkinson's Foundation. Setting guidelines for
who should and shouldn't drive with Parkinson's, Lieberman tells
WebMD, "is a very difficult task, and it may be an almost impossible
task. … There are no established guidelines for this because I think the
nature of the problem is so complicated … you can't make a blanket
statement." Still, Lieberman says, "I applaud a study like this because
somebody's got to start to lay out the nature of the problem." Zesiewicz
and her colleagues recruited 39 Parkinson's patients, mostly around age
65, and matched them up with 25 people of similar age and the same
gender who did not have the disease. The functional abilities of the
participants with Parkinson's -- some of whom had already quit driving --
were gauged based on several common medical tests. All the
participants were then tested in a driving simulator. The Parkinson's
patients had a "significantly greater number of total collisions on driving
simulation" than the other group, Zesiewicz writes. Among these
participants, the total collision scores correlated with how well they had
done on their functional tests. The Parkinson's patients' own reports of
their driving abilities, though, did not match up. That's not surprising,
according to Lieberman. "Usually the patient doesn't come and say, 'I'd
better not drive.' One, they don't want to say it, and two, they're
probably not aware," Lieberman tells WebMD. He says he had one
patient in an early stage of the disease whose right arm didn't work as
well as the left. But the man wasn't aware he had this problem until his
wife told him he kept veering to the right while driving. "He had no
idea," Lieberman says. "Some of it is fairly obvious. A person who can't
get out of a chair, can barely move their legs, it's fairly simple they can't
drive," Lieberman tells WebMD. "But if you take someone with
Parkinson's disease who has trouble walking, who is slow in reacting --
how are they going to do in a car?" "Many patients with Parkinson's
diseases are not safe to drive not only because of potential sleepiness,
but because their reaction times are compromised, their thinking, their
judgement can be compromised," Montgomery tells WebMD. Liggett
knows the feeling from personal experience. "Parkinson's slows your
reaction time; it makes you stiff, it makes your muscles not react when
you tell them to move, like you say, 'OK, foot, step on brake,' and it says,
'OK, I'll think about it,'" she tells WebMD. But Liggett says that even
when her body doesn't cooperate, her mind is fine. If, for instance, her
medication wears off, she says she tries to pull over and wait until it
begins working. But when is enough enough? Liggett admits it's a
difficult question: "I guess I would have to make that decision when I
was no longer able to have enough good periods where my driving was
safe, so that I was having to drive when it was unsafe." When
Montgomery sees a Parkinson's patient he has concerns about or, as is
more likely, if a family member voices concerns, Montgomery refers the
patient to an occupational therapist for testing. Lieberman says he
insists the patient take a driving test, preferably under the official eye of
the state motor-vehicles department. As Zesiewicz writes, "Further
investigation aimed at identification of early risk factors for poor driving
ability is warranted." But this must be done carefully. "If they start taking
licenses from all Parkinsonians, that would be a major, major issue,"
Liggett says. There are many good reasons any rational adult would not
want to give up their driving privileges, Montgomery tells WebMD. "In
the United States, public transportation is not so great," Montgomery
says. "It's not like Europe, where you can get public transportation quite
easily. Taking away somebody's ability to drive can be a major, major
problem." Nobody understands that better than Liggett. "It would be
very difficult for me to get anywhere without my car. I have wonderful
neighbors, but they have their own lives, too. It would definitely be a
problem, but I don't want to kill anybody on the highway either. So it's
something that I have to deal with at some point," she says. Vital
Information: Parkinson's disease is a degenerative disease of the central
nervous system in which the region of the brain that controls movement
gradually deteriorates. In a recent study, researchers found that
Parkinson's patients were more likely to have collisions during a driving
simulation, but these patients were not aware of their diminished driving
abilities. Guidelines do not exist on which Parkinson's disease patients
should be driving and which should not, because the issue is so
complicated, with lots of variation among patients.

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