I’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:
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