October 30, 2009
Bad Driving Down To Brain Gene Variants?

30% of the American public carry a gene that probably makes them more dangerous on the road. Hey, these people ought to move to cities and take mass transit.

Bad drivers may in part have their genes to blame, suggests a new study by UC Irvine neuroscientists.

People with a particular gene variant performed more than 20 percent worse on a driving test than people without it - and a follow-up test a few days later yielded similar results. About 30 percent of Americans have the variant.

"These people make more errors from the get-go, and they forget more of what they learned after time away," said Dr. Steven Cramer, neurology associate professor and senior author of the study published recently in the journal Cerebral Cortex.

We are not all as well adapted genetically to industrialized civilization. This one gene, brain-derived neurotrophic factor (BDNF), is just one of many genes where we differ from each other in our ability to handle the many products and environmental niches we've created with industrialization. Some people can't handle beer or cocaine or addictive drugs. Some other people can't handle the sleep deprivation made easier by Thomas Edison's invention of the light bulb. Still others can't handle easy access to online gambling or online porn.

Not enough BDNF means your brain functions less well behind the wheel.

This gene variant limits the availability of a protein called brain-derived neurotrophic factor during activity. BDNF keeps memory strong by supporting communication among brain cells and keeping them functioning optimally. When a person is engaged in a particular task, BDNF is secreted in the brain area connected with that activity to help the body respond.

I wonder whether 29 people can provide enough data points to demonstrate an effect. But if the effect is strong maybe it can.

The driving test was taken by 29 people - 22 without the gene variant and seven with it. They were asked to drive 15 laps on a simulator that required them to learn the nuances of a track programmed to have difficult curves and turns. Researchers recorded how well they stayed on the course over time. Four days later, the test was repeated.

Results showed that people with the variant did worse on both tests than the other participants, and they remembered less the second time. "Behavior derives from dozens and dozens of neurophysiologic events, so it's somewhat surprising this exercise bore fruit," Cramer said.

In the future will some people look at their brain gene test results and decide to live next to a subway stop?

Update: If this discovery holds up under further investigation it will be unusual. In the search for genes that influence cognitive ability the researchers are finding that it is hard to find the genetic variants which contribute to differences. They know the variants are there from twins studies and other studies on populations. The thinking now is that bulk of the variants which influence cognitive ability each have only a small influence. So much larger populations are needed to find them.

Researcher Robert Plomin comments that so far the genetic differences influencing IQ appear to each contribute very little to the total differences.

Failing to find genes for intelligence has, in itself, been very instructive for Plomin. Twin studies continue to persuade him that the genes exist. “There is ultimately DNA variation responsible for it,” he says. But each of the variations detected so far only makes a tiny contribution to differences in intelligence. “I think nobody thought that the biggest effects would account for less than 1 percent,” Plomin points out.

That means that there must be hundreds--perhaps thousands--of genes that together produce the full range of gene-based variation in intelligence.

Check out this brief essay by Plomin about IQ and genes in Technology Review.

Share |      Randall Parker, 2009 October 30 11:51 PM  Brain Genetics

Kudzu Bob said at October 31, 2009 7:18 AM:

Thirty percent of Americans are geneticaly bad drivers, and half of 'em live in my town...

odograph said at October 31, 2009 7:21 AM:

Um. If "these people make more errors from the get-go, and they forget more of what they learned after time away," we might also expect an unfortunate correlation to 401K balance. This would probably affect both savings rate and investment choice. (A post "blank slate" world leads to new problems of ethics.)

Dave Tufte said at October 31, 2009 9:09 AM:


You've had enough statistics to know that a sample size of 29 is just fine for making inferences: degrees of freedom and t-distributions largely solved that issue a century ago.

The key is if the sample is sufficiently random. Given the degree of genetic randomness found in something like the National Geographic special where they picked people off the street in Queens, it's probable that any decent social scientist could form a pretty valid sample of 29 people.

Randall Parker said at October 31, 2009 9:38 AM:

Dave Tufte,

But since I do not know that they used a sufficiently random sample I prefer bigger sample sizes.

Also, sample size of 29 seems small to me for a different reason: I know huge numbers of genetic variants influence cognitive function. Robert Plomin (a gene IQ researcher) expects from his research so far that few or no genetic variants influence IQ by more than 1 IQ point (obviously harmful genetic variants that cause retardation are an exception and a Jewish dystonia mutation provides a big boost).

So I'm a little suspicious that a single common mutation can make such a big difference. Not saying it is untrue. But I bring a lot of knowledge about other genetic studies on the brain to my view of this.


Of course genetic variants be found to underlie impulsiveness, savings rate, conscientiousness, and many other cognitive attributes (not just IQ) that influence financial success and willingness and ability to take care of one's affairs in an industrial society in a responsible manner. More nails are getting hammered in the Blank Slate coffin every day.

Few people are aware of how genetic sequencing and testing costs have dropped many orders of magnitude in recent years and how the flood gates have opened on genetic testing studies. We are about to be hit by an avalanche of results mapping behaviors and ability to genetic variants.

Nick G said at October 31, 2009 9:54 AM:

The next question is, of course, treatment. What will boost BDNF?

The question after that is, what would be the disadvantages of more BDNF - more difficulty forgetting trauma?

Larry said at November 1, 2009 9:13 AM:

Possible solution?
"Could Some Forms Of Mental Retardation Be Treated With Drugs?
Abnormalities in the number and shape of dendritic spines, the protrusions that allow communication between brain neurons, have been observed in patients with mental retardation. Previous research led by Baoji Xu, PhD, associate professor in the department of pharmacology, has shown that brain-derived neurotrophic factor (BDNF), a growth factor synthesized in dendrites, regulates the number and shape of dendritic spines required for spatial learning and memory.

These results highlight the role of BDNF in mental retardation, Xu says, and indicate that increasing the transport of these growth factors may be a way to treat these conditions."


No word on how to boost BDNF but at least someone is looking.

Lono said at November 2, 2009 8:27 AM:


I knew a particular brother and sister of recent Greek ancestry in High School - who were exceptionally bright and talented - but whom were nearly incapable of learning how to drive correctly.

I do not know if this particular phenotype could be the same cause - since the sister went on to be a professor, and the brother went on to start his own succesful company, but it was really unbelievable how inept they were at driving - both having to take the driving test at least five times until finally being given a licence - and this in a state that basically only required you to go once around the block to pass!

Within a few months of the brother getting his licence he accidentally clipped a motorcycle cop - so clearly it wasn't just nerves that held them back from competent driving - but apparently a real phenotypic disability.

I, myself, throw no sones as I seem to have a poorly functioning geniculate nucleus, so while I am an excellent driver ;-) I rarely know which way I am intending to drive to. GPS has been quite the Godsend for me in this resepct!

mike said at November 2, 2009 1:39 PM:

Funny...I thought it was just a lack of a Y chromosome ;-)

Barry D said at November 2, 2009 1:47 PM:

Uh, this is a simulator.

This may be a video game gene, more than a driving gene.

It would be interesting to see a followup done in real cars, on a real track.

Mark Turner said at November 2, 2009 1:47 PM:


If they cure this, the Democrat paty will be toast. Therefore, the dems will never allow such conditions to be treated.

JorgXMcKie said at November 2, 2009 1:49 PM:

Kudzu Bob, obviously most of the genetically bad drivers reside in Michigan.

Q. Why don't they allow Michiganders to race in NASCAR races?

A. Because even though there are only two real rules [1. Go fast. 2. Turn Left], 98% of Michigan drivers can't follow the second one.

AMac said at November 2, 2009 2:17 PM:

29 is way too small a number! Actually, 7 (people with the BDNF variant) is the number that's way too small.

One of the side stories of genome wide association studies (and similar) is that numbers of subjects in the high hundreds and low thousands seemed like more than enough to find whatever was there. Now, in the wake of a raft of didn't-find-em results, there's re-assessment. Need chips with more features (not relevant to this story, where the feature of interest is already ID'ed), and need more subjects per study.

If this particular BNDF feature is that high in predictive power and that common (30% of the population!) then either these researchers got incredibly lucky, or ... well, I can't think of an alternative.

And why didn't this BDNF variant pop up at the top in any number of earlier studies that tracked various behavioral or psychometric outcomes? It affects only driving?

Interesting study -> press release -> media attention -> poster at meeting -> chatter -> obscurity

I wish 'em luck, but I won't be holding my breath.

soumynona said at November 2, 2009 4:44 PM:

I'm looking forward to the studies correlating BDNF to race.

Oh, what am I saying? OF COURSE there's NO way that could EVER be correlated. After all, people are exactly the same! EXACTLY THE SAME! Ex-ACTLY. The. SAME.

Drew Kelley said at November 2, 2009 4:46 PM:

Sounds like they need a research grant and to set-up shop in an "average" DMV office in the state, and track all new/renewal drivers for a couple years.

comatus said at November 2, 2009 6:12 PM:

"...these people ought to move to cities and take mass transit." Right, because making "more errors from the get-go, and they forget more of what they learned," lacking communication between brain cells, and being poorly "adapted genetically to industrialized civilization" are just gonzo success factors for life in the big city. Grow up.

There's a level of stupid that goes beyond just politcally stupid. Gosh, it might be genetic!

el polacko said at November 2, 2009 6:19 PM:

well that explains the asian drivers.

john b said at November 3, 2009 6:01 AM:

I would have thought it was a chromosome difference that accounted for bad drivers.

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