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Delay discounting

The phenomenon scientists call “delay discounting” can tell a lot about a person’s ability to set and attain goals. Some people are more likely to prefer smaller but immediate rewards rather than larger but delayed rewards. The tendency to prefer immediate rewards, even if they are smaller, has been linked to impulsive behavior, which is connected to problems such as substance abuse and addiction. Studying twins over a number of years, Washington University researchers have found that genetic factors underlie the preference for short-term rewards. The researchers also have identified genes linked to the brain’s serotonin and opioid systems as contributors to the preference for rewards now rather than later.

IF YOU’D RATHER HAVE A SMALL REWARD NOW VERSUS SOMETHING BIGGER LATER, YOU MAY BE AT RISK FOR PROBLEMS LIKE ADDICTION OR OBESITY. PEOPLE WHO TEND TO CHOOSE SMALLER, BUT IMMEDIATE, REWARDS OVER LARGER PRIZES THAT THEY HAVE TO WAIT FOR ALSO MAY BE A BIT DIFFERENT GENETICALLY, ACCORDING TO NEW RESEARCH FROM WASHINGTON UNIVERSITY SCHOOL OF MEDICINE IN ST. LOUIS. JIM DRYDEN HAS MORE…

THE PHENOMENON IS CALLED DELAY DISCOUNTING. WHAT IT MEANS IS THAT WAITING ISN’T WORTH IT FOR SOME PEOPLE. THE WAY SCIENTISTS IDENTIFY THOSE WHO DISCOUNT DELAYED REWARDS IS BY ASKING QUESTIONS SUCH AS WOULD YOU RATHER HAVE 5 DOLLARS NOW OR 10 DOLLARS TWO WEEKS FROM NOW? WASHINGTON UNIVERSITY RESEARCHER ANDREY ANOKHIN HAS BEEN FOLLOWING MORE THAN 600 TWINS FOR SEVERAL YEARS NOW AND ASKING THEM THOSE SORTS OF QUESTIONS.

(act) :25 o/c 100 later

We started asking, “Would you prefer $95 today or $100 in

9 months?” Most people would say, “I’d rather have 95 now.”

But then we asked, “What about 85 today versus 100, 90 days

later?” Then people, some people, start preferring 100 later.

ANOKHIN SAYS PEOPLE WHO ALWAYS PREFER SMALLER, BUT IMMEDIATE, REWARDS TEND TO BE MORE IMPULSIVE, AND IMPULSIVE PEOPLE ARE AT RISK FOR PROBLEMS SUCH AS SUBSTANCE ABUSE AND OBESITY. HE SAYS THE RESEARCH SHOWS THAT DISCOUNTING OF DELAYED REWARDS HAS TENDED TO DECLINE A BIT AS KIDS HAVE GOTTEN OLDER, BUT HE SAYS GENERALLY THOSE WHO DISCOUNT THOSE DELAYED REWARDS WILL CONTINUE TO PREFER MORE IMMEDIATE GRATIFICATION.

(act) :15 o/c at all

Some people are high discounters, so, basically, the

subjective value of delayed reward diminishes very fast,

with increasing delay. Some people don’t delay at all.

AND AS HE’S FOLLOWED THE TWINS FROM THEIR EARLY TEENS INTO THEIR EARLY 20s, ANOKHIN HAS FOUND THAT THE RESULTS ALSO SHOW A GENETIC CONNECTION.

(act) :11 o/c age 20

And then we, again, did this genetic analysis in twins, and

we found that this was heritable at both age 16 and 18. And

we also are finding strong genetic influences at age 20.

HIS TEAM HAS LINKED A FEW GENES TO THE PROPENSITY TO PREFER IMMEDIATE REWARDS, EVEN WHEN THEY ARE SMALLER. AND HE SAYS THE GENES ALSO ARE LINKED TO IMPULSIVITY AND TO SUBSTANCE USE.

(act) :22 o/c opioid receptors

Our, kind of, “first wave” of analysis showed that serotonin

genes were the most important. More recent analyses have updated

this significantly, and actually, it’s no longer serotonin genes.

They are also significant and important, but now our first “hits”

are genes related to the kappa opioid receptors.

THOSE RECEPTORS ARE INVOLVED IN MODULATION OF NEUROTRANSMITTERS THAT REGULAT REWARD BEHAVIORS, SUCH AS DOPAMINE…AND SEROTONIN, AND IN ANIMAL STUDIES BOTH THE KAPPA OPIOID AND SEROTONIN RECEPTORS HAVE BEEN LINKED TO DEPRESSION-LIKE BEHAVIOR AS WELL AS TO DRUG-SEEKING BEHAVIOR. SO ANOKHIN SAYS IT’S POSSIBLE THAT THEY’RE CONNECTED TO THOSE THINGS IN HIS STUDY SUBJECTS, TOO.

(act) :15 o/c of course, obesity

We certainly will be doing extensive analysis, focused on the

correlations of individual differences of delay discounting with

substance use, or abuse and dependence symptoms, psychopathology,

and, of course, obesity.

ANOKHIN PRESENTED HIS FINDINGS AT THE ANNUAL MEETING OF THE AMERICAN COLLEGE OF NEUROPHARMACOLOGY. I’M JIM DRYDEN…

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