SNPWatch: Genetic Variation Influences How We Respond to Reinforcement

By Bethann Hromatka

 

Editor’s note: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who purchased prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will not. Those customers will have access to ancestry information as well as access to their uninterpreted raw data.

 

The human brain is hardwired to receive chemical signals from our environment. It primarily does this through receptors—proteins on the surfaces of cells that catch specific molecules when they pass by. An interesting class of receptors is the mu-opioid receptors, so named because they influence responses to opiates (for instance morphine). These receptors are also involved in processing reward and dealing with stress.

A few years ago, researchers identified a SNP ( in the opioid receptor gene OPRM1) associated with alcohol addiction. This SNP also appears to be involved in processing responses to physical and emotional pain. In addition, studies have linked to heroin addiction and responses to Naltrexone, a medication used to treat alcohol dependence and heroin addiction.

(23andMe customers can view their genotype at by using the Browse Raw Data feature or view their reports for Heroin Addiction and Naltrexone Treatment Response in their accounts.)

A study published this month suggests that also influences learning through positive reinforcement. The researchers behind this study tested if individuals with different versions of were more or less likely to continue choosing the right answer in a video game if they received reinforcement (in the form of a small cash prize) for correct answers.

The authors found that positive reinforcement prompted individuals with the AA genotype at to continue to choose the right answer over time. That is, positive reinforcement motivated these individuals to learn. In contrast, individuals with at least one copy of the G version at (AG or GG) were less motivated by positive feedback—these participants did not continue to choose the right answer over time.

In general, giving a child ice cream for good performance on a spelling bee will prompt him/her to continue to learn, and this study suggests that such responses are influenced by genetics. This report also suggests that the same version of is simultaneously involved in reinforcement learning, which many consider to be a beneficial behavior, and alcohol addiction, an unhealthy behavior. Studies like this one may eventually help elucidate the pathways that govern both normal human conduct and complex disorders.

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.


  • Justin Loe

    I believe there’s another paradox here which is that the less adaptive (less receptive to positive reinforcement) variants (AG, GG) are in substantial portions of the population. From an evolutionary standpoint it would seem logical that this variant would have been selected against, or, alternatively, that rs1799971 and being less susceptible to positive reinforcement is adaptive in certain conditions

    • http://23andme.com Shwu

      Hi Justin,

      Yes, it’s very interesting how variants like rs1799971 may have evolved. In Europeans, about 30% of people have one or two copies of the G version. Altogether, though, the A version is still nearly 5 times more common than the G version.

  • Justin Loe

    If verified, this result would cause serious problems for social science theories based on rational choice, particularly in economics. I’ve been a bit skeptical of rational choice theories, but I admit I’m a bit skeptical of this result, which implies that potentially 30% of Europeans and apparently 65% of Japanese have poor responses to positive reinforcement. Although possible it seems implausible.

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