SANTA ANA, Calif. — We might never be able to feel sympathy
for the speeding driver who swerves into our lane, barely missing the bumper,
only to cut back into his original lane a quarter-mile later. But new research
may at least help us understand him.
A new study at the University of California, Irvine, reveals
that people with a gene variation that gives them less of a brain protein
linked to memory retention performed more than 20 percent worse in a driving
simulation than people who had higher levels of the protein.
So can lousy drivers blame their lack of awareness, slow
reaction time and ill-considered risk-taking — in short, their infuriating
awfulness — on their DNA? Since about 1 in 3 Americans appears to have the gene
abnormality, not necessarily. But it could be a factor.
“Any behavior is the sum total of a number of different
genes and factors, but this definitely suggests that this particular gene does
affect short-term motor learning,” said Stephanie McHughen, a graduate
student in UCI’s Department of Anatomy and Neurobiology and the lead author of
the study, which appeared recently in the journal Cerebral Cortex.
The researchers, led by Dr. Steven Cramer, chose 29 healthy
volunteers ages 18-30. Twenty-two of the subjects had the normal gene that secretes
a protein called brain-derived neurotrophic factor, or BDNF. The protein
facilitates communication among brain cells and keeps the memory fresh. The
other seven subjects were known to have the gene variant, which limits the
secretion of BDNF.
The subjects were asked to drive a video gamelike simulator,
complete with steering wheel and a monitor showing a racetrack, for 15 laps.
The course was filled with tricky curves, and the drivers were graded on how
far they deviated from the center.
Not only did the protein-deficient drivers perform worse on
the initial exercise, they also retained less information about the course than
their protein-rich counterparts when the exercise was repeated four days later.
While the test group was small, the research has
implications for people who have suffered memory loss from brain or spinal
trauma, such as accidents or strokes.
BDNF “gushes out” after such an event, said
Cramer, an associate professor in UCI’s Neurology and Anatomy and Neurobiology
departments.
But if the gene variant reduces the level of secreted BDNF
in these victims, it also could slow their cognitive and motor-skill
development as they recover.
“Let’s assume that evidence this compass is pointing to
is true: that one-third of people have lesser outcomes after an injury as a
result of this genetic variation,” Cramer said. “Then we need to do
something different for these people.”
One person who posted a link about the study on Twitter
referred to those in the protein-deficient minority as “mutant drivers,”
which is unfair, Cramer said.
“If 1 in 3 people have it, you can’t call it a defect.
This is not a disease or a mutation, it’s a different approach … it’s as if
nature’s rolling the dice.”
Cramer said the gene variant could actually help people who
have long-term, degenerative disorders that affect their motor functions, such
as Parkinson’s or multiple sclerosis, as opposed to short-term trauma.
Some people aren’t ready to attribute poor performance
behind the wheel to genes. Diane Moore, who runs A to Z Driving School in
Anaheim, Calif., and has been a driving instructor for 13 years, says the
study’s premise ignores students’ capacity to learn and correct their bad
behavior.
“I had a customer the day before yesterday who’s a very
well-educated university professor who lost his license because he had failed
his driving test,” Moore said.
“He knows how to drive, but we were helping him with
different techniques and tools to help him make better decisions. And he retook
the test and passed.”
Cramer responded that the gene “is only one influence
on behavior,” and he’s seeking to learn more. His study was funded by the
National Institutes of Health, and more money is available for follow-up
research.
The new research will examine subjects’ mastery of a
different functional task, and over a longer period of time — say, three weeks.
“This starts to get into the time period that’s
relevant for people with stroke or spinal-cord injury,” he said.
“That is a ‘golden period,’ where it’s like a newborn brain — so ready to
learn.”
