Human Nature: Science, Technology, and Life.

Genes, Murder, and Bad Driving

Can crimes and crashes be blamed on bad genes?

On Friday, Nature reported details of an Italian case in which a court, for the first time in Europe, reduced a criminal sentence based on a genetic theory of behavior. According to the report:

Pietro Pietrini, a molecular neuroscientist at Italy's University of Pisa, and Giuseppe Sartori, a cognitive neuroscientist at the University of Padova, conducted a series of tests [on the defendant] and found abnormalities in brain-imaging scans and in five genes that have been linked to violent behaviour—including the gene encoding the neurotransmitter-metabolizing enzyme monoamine oxidase A (MAOA). A 2002 study ... had found low levels of MAOA expression to be associated with aggressiveness and criminal conduct of young boys raised in abusive environments. In the report, Pietrini and Sartori concluded that [the defendant's] genes would make him more prone to behaving violently if provoked. ... On the basis of the genetic tests, Judge Reinotti docked a further year off the defendant's sentence, arguing that the defendant's genes "would make him particularly aggressive in stressful situations". Giving his verdict, Reinotti said he had found the MAOA evidence particularly compelling.

Scientists interviewed by Nature say this kind of genetic determinism is too crude and tenuous to justify sentence reductions. Genes operate in relation to each other, not independently, and they produce different effects depending on environmental factors and population differences such as ethnicity. My colleague Dan Engber, who alerted me to the Nature report, has made similar points about brain scans and neuro-determinism. I'm highly sympathetic to his indictment of the field.

Despite these criticisms and the skepticism of judges, Nature reports that according to a database maintained by Nita Farahany of Vanderbilt law school,

in the past five years there have been at least 200 [U.S.] cases where lawyers have attempted to use genetic evidence to support the idea their clients' were predisposed to violent behaviour, depression or drug or alcohol abuse. In Britain, there have been at least 20 such cases in the past five years.

And don't be surprised if the next target of genetic determinists is car crashes. Neuroscientists from the University of California at Irvine have just laid out the case in a paper in Cerebral Cortex, accompanied by a catchy press release. The release is titled, "Bad driving may have genetic basis, UCI study finds." It reports:

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. ... 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.

The release explains how the gene works:

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.

The study, funded by the National Institutes of Health, will surely become fodder for defense attorneys in civil and criminal cases involving crashes or dangerous driving. And these lawyers won't be alone in their interest. In the press release, Steven Cramer, the neuroscientist who led the study, says, "I'd be curious to know the genetics of people who get into car crashes. I wonder if the accident rate is higher for drivers with the variant."

I bet every auto insurer would like to know the same thing.

I'm counting on Engber to pick apart the study and the press release. Let's hope the authors are oversimplifying the impact of genes on behavior. Because if the link between genes and driving performance is solid enough to justify reduced sentences and damage awards, it's hard to see why insurances shouldn't be allowed to test and charge you accordingly.

Anti-Theft Drugs

Can a drug cure the urge to steal?

It looks that way. In the April 1 issue of Biological Psychiatry, scientists from the University of Minnesota School of Medicine report:

An 8-week, double-blind, placebo-controlled trial was conducted to evaluate the safety and efficacy of oral naltrexone for kleptomania. Twenty-five individuals with DSM-IV kleptomania were randomized to naltrexone (dosing ranging from 50 mg/day to 150 mg/day) or placebo. ... Subjects assigned to naltrexone had significantly greater reductions in ... stealing urges (p = .032), and stealing behavior (p < .001) compared with subjects on placebo. Subjects assigned to naltrexone also had greater improvement in overall kleptomania severity ... Naltrexone demonstrated statistically significant reductions in stealing urges and behavior in kleptomania.

It sounds like an April Fools' joke. But it isn't. In an interview with Reuters, the study's lead author explains that naltrexone "gets rid of that rush and desire" to steal.

Naltrexone is better known as a drug for alcohol or drug addiction. Many of us, while accepting these addictions as diseases, continue to regard theft as a matter of personal responsibility. Should we rethink that distinction? If the same drug relieves both conditions, should we take kleptomania more seriously as an illness?

The floor's open.

The Gambling-Addiction Defense

Chalk up another victory for the gambling-addiction defense.

Yesterday, attorneys for Tim Donaghy, the former NBA referee who admitted to betting on basketball games he officiated, filed a psychological "evaluation" that blames his crimes on compulsive gambling. The author is Stephen Block, a gambling treatment counselor. Sample quotes from the evaluation, as reported by the Associated Press: 1) "In my professional opinion, Mr. Donaghy would never have committed these offenses if he was not a pathological gambler." 2) "His gambling history demonstrates the need to gamble to fulfill the underlying need for 'action.' " 3) "He could not stop himself from gambling." The Washington Post supplies one more: 4) "His judgment and insight were impaired by his gambling behavior."

The plea worked. Today, Donaghy was sentenced to 15 months in prison instead of the 27 to 33 months that had been expected. According to the Post, the judge "said she took Donaghy's gambling addiction into account, as well as his cooperation with the government's investigation." Reuters quotes the judge on Donaghy's gambling addiction: "Although it contributed to his criminal conduct, it does not excuse it." No excuse, but a nice contribution: His sentence gets halved.

I'm not going to sit here and claim that compulsive gambling doesn't exist. But disorders that are powerful and real for some people have a way of being diagnosed in other people who don't share many of the symptoms but just happen to need a legal excuse. In this case, all we have is an evaluation solicited and supplied by the defendant's attorneys.

More to the point—and this is the crazy part—in this case, the crime is gambling. If you plug that information into the evaluation, here's what it boils down to: "Mr. Donaghy would never have committed this gambling if he was not a pathological gambler." No kidding! He committed gambling because "he could not stop himself from gambling," because "his judgment and insight were impaired by his gambling." How do we know his gambling is compulsive? Because of his "gambling history." The circularity is shameless.

And don't even get me started on the idea that Donaghy had a "need to gamble to fulfill the underlying need for 'action.'" An "underlying need for action" pretty well describes the motivation for half the world's crimes.

If you really believe Donaghy's gambling was addictive, don't just make it a mitigating factor in sentencing for the crime of gambling. Abolish the crime. Because a crime can't excuse itself.