Scientists have found a genetic signature for delay discounting—the tendency to undervalue future rewards—that overlaps with attention-deficit/hyperactivity disorder (ADHD), weight and smoking. The work was published today in Nature Neuroscience from researchers at the University of California San Diego School of Medicine.
In this study, the researchers looked at genetic data from 23andMe research participants who answered survey questions that could be used to assess delay discounting. An example of a question was, "Would you rather have $55 today or $75 in 61 Days?"
From the survey questions and the genetic data, the research team found a number of genetic correlations.
"We discovered, for the first time, a genetic correlation between ADHD and delay discounting," said first author Sandra Sanchez-Roige, Ph.D., a postdoctoral researcher in Abraham Palmer's lab. "People with ADHD place less value in delayed rewards. That doesn't mean that everyone with ADHD will undervalue future rewards or vice versa, just that the two factors have a common underlying genetic cause."
The researchers also found that delay discounting was linked to smoking initiation and a higher body mass index (BMI). This means that people who tended to undervalue future rewards were more likely to have a higher BMI, start smoking or less are less likely to quit smoking.
In addition, there were also negative correlations also found. The group found that delay discounting negatively correlated with college attainment, years of education and childhood IQ.
Palmer's team is now studying delay discounting in rodent models to see if their behavior would change if they experimentally changed the same delay discounting-related genes.