Cognitive Daily

ResearchBlogging.orgI’ve just read an engrossing report about some very promising research in a an exciting field. The researchers combined fMRI research with genetic analysis to see if they could identify a genetic basis for anger. And they actually found something quite interesting.

If I was writing for the New York Times, the headline might read something like this: “Researchers identify gene responsible for regulating anger.” For the Washington Post, it could be “Is there an anger gene?” For the New York Post, perhaps simply “RAGE GENE FOUND.”

But those headlines, while they are in some ways accurate, don’t really tell the whole story. A team led by Martin Reuter was intrigued by findings linking the gene for a protein, DARPP-32, with antisocial and addictive behaviors. DARPP-32 is involved in regulating the dopamine signaling pathway in the brain. When the brain has elevated dopamine levels, it has a lower threshold for anger and aggression, so DARPP-32 may be the key to understanding why some people are quicker to anger than others.

The gene that encodes DARPP-32 has been fully sequenced, and a variation in just one tiny section of the gene, it turns out, may have a direct impact on human behavior. A gene sequence is simply a string of nucleotides. There are four possible nucleotides, represented by the letters C, T, A, and G. In DARPP-32, just two nucleotides are related to the antisocial and addictive behaviors. Out of a long string of nucleotides, it turns out, it matters a lot whether one set of two particular elements is CC, CT, or TT. But does it directly affect anger?

Reuter’s team tested 838 adults by taking a sample of their genetic material from the cheek. The same volunteers were also given a 110-question test for trait anger (the ANPS), which has been shown to be a reliable measure of how disposed the individual is to respond to a stressful situation in anger. The DARPP-32 gene of each participant was tested to see whether the key nucleotide pair was CC, CT, or TT. Here are the results:

i-bbbce72ba4f4cd57694bb3c2aef30d29-reuter1.gif

As you can see, when the key pair was TT or CT, anger scores were significantly higher than for those who had the CC sequence. Anger scores are on a four-point scale ranging from 0 to 3, and the difference was on the order of a quarter of a point — not huge, but nothing to sneeze at either.

But here’s the thing. 96 percent of respondents have the TT or CT sequence. Only 37 of the 838 people tested possessed the CC sequence. If TT and CT are associated with higher anger and these people constitute 96 percent of the population, then what has been identified is a gene for normal anger, not exceptional anger (at least among the German population tested, which had screened out people with diagnosed psychopathologies). The real find is the CC sequence: a gene for mildness or even-temperedness.

But we all know there are plenty of people who are quick to anger, and in this study we can see that the DARPP-32 gene isn’t responsible (or at least not solely responsible) for that. It’s possible that social components of anger outweigh genetic predisposition. Or it may be that some other gene or combination of genes predisposes people to anger.

Reuter, M., Weber, B., Fiebach, C., Elger, C., & Montag, C. (2009). The biological basis of anger: Associations with the gene coding for DARPP-32 (PPP1R1B) and with amygdala volume Behavioural Brain Research, 202 (2), 179-183 DOI: 10.1016/j.bbr.2009.03.032

Comments

  1. #1 Jenny
    October 14, 2009

    I can tell you from personal experience that if this were reported in the NYT, the headline would not resemble the findings of this research nearly as closely as you imagine.

    But anyway, what you’re saying is they just found the potential genetic basis for being a wussy? Now, THAT’S interesting!

  2. #2 Bjørn Østman
    October 14, 2009

    Anger scores are on a four-point scale ranging from 0 to 3, and the difference was on the order of a quarter of a point — not huge, but nothing to sneeze at either.

    What are the standard errors? Without knowing those this could equally well be highly significant or completely uninteresting. With only 37 CC people, I wonder if the error bars don’t overlap.

    [Making the effort to look up the paper] I see that the figure has some error bars, but it is not mentioned what kind in the figure caption. They say:

    Results of the ANOVAs: genotype level: F(1,837) = 9.52, p = 0.002; allele level: F(2,836) = 5.33, p = 0.005.

    So I suppose the difference is significant, even though I don’t understand the genotype/alle level difference.

  3. #3 Dave Munger
    October 14, 2009

    Bjørn,

    My guess is the error bars are standard errors, but the results are indeed significant.

    FWIW, I think “allele level” means anger ratings for people having a “C” anywhere in the pair of nucleotides were significantly different from people who did not have a “C”. “Genotype level” means anger ratings for TT and CT were significantly different from CC.

  4. #4 Bjørn Østman
    October 14, 2009

    Sounds plausible. Thanks.

  5. #5 Jirka Lahvicka
    October 15, 2009

    What do these results mean in real life? Would you be able to tell apart people with 2.5 score and people with 2.25 score based on their day-to-day behavior (e.g. if they were your friends or coworkers)? What is the usual standard deviation of the anger score? Is there some difference between people of different biological genders or of different ages?

  6. #6 Botuh
    October 20, 2009

    thanks

  7. #7 Mark Tyrrell
    October 21, 2009

    It’s also interesting that people prone to anger are also at the most risk of heart disease (regardless of other lifestyle factors) and also regardless of whether they express that anger or “release it”. Even recalling times when we were angry

    In one study conducted at Stanford Medical School, heart patients were asked to recall times when they had been angry. Although, according to the patients, the anger they felt on recalling the events was only half as strong as it had been during the original experience, their hearts started pumping, on average, 5% less efficiently. Cardiologists view a 7% drop in pumping efficiency as serious enough to cause a heart attack.

    People talk about genes for heart disease and shilst a medical family history is to be considered generally lifestyle factors tend to tip the balance into health and disease-I’d say-life style and social learning are very important factors in developing an angry personality. Also, of-course the “buzz” from the attention received from others and chemical energy of anger can make it addictive.