Whether you would prefer a smaller reward right now or would rather wait for a bigger reward later may depend largely on your genes, according to a new study at the Washington University School of Medicine in St. Louis.
Research has shown that people who tend to opt for immediate smaller rewards are at greater risk for struggling with problems such as impulsivity and addiction. The new findings show that these decision-making tendencies have a genetic link to the brain pathways associated with these disorders.
“Every day we make decisions about obtaining immediate gains, which come at the cost of delayed but larger advantages,” said principal investigator Andrey Anokhin, Ph.D., associate professor of psychiatry. “We found that many such decisions are explained by genetic factors that also are related to mood and impulsivity.”
For the study, the scientists evaluated 310 adolescent identical or fraternal twin pairs and asked them questions about money. At 12 years of age, and again at age 14, the participants were given the choice of receiving seven dollars immediately or $10 in the mail two weeks later. At age 12, 35 percent decided to take seven dollars right away instead of more money later. That number fell to 27.5 percent when the same kids were presented the scenario at age 14.
The scientists looked at several genes previously linked to impulsivity and substance use. They found that genes linked to the brain’s serotonin and kappa opioid receptors — neuronal receptors associated with mood, depression, and addiction — played a role in whether the participant chose an immediate reward over a more sizeable payoff later.
And while the participants were slightly more likely to accept delayed rewards as they got older, the researchers found that those who initially preferred immediate rewards were more likely to continue choosing quick payoffs.
When an individual doesn’t want to wait for a larger reward, that could be an indication that the person is impulsive, Anokhin said. Impulsivity increases the risk for problems such as alcoholism, drug addiction, and obesity.
In subsequent experiments at ages 16, 18, and 20, the same participants were offered hypothetical monetary rewards, $80 now or $100 six months from now, for example.
“We vary the amount of the reward available immediately, the amount of the delayed reward and the time they would have to wait,” Anokhin said. “If you offer someone the choice between $95 today or $100 in six months, most people would rather have the cash immediately. But what if the choice is between $85 today or $100 in three months? At that point, some people prefer delaying the reward to make an extra $15.”
As the twins in the study have aged, the researchers are looking for possible connections between this sort of decision-making and binge drinking, drug use, and nicotine dependence.
“We need to look more closely before drawing conclusions, but we want to see what the consequences of the differences we’ve identified are for real-life behaviors,” he said.
The researchers reported their findings at the annual meeting of the American College of Neuropsychopharmacology in Hollywood, Fla.