Giles W. Story, PhD, from the University College London

Giles W. Story, PhD

 Delay Discounting vs Traditional Predictors of MDD Relapse, With Giles Story, PhD

New evidence suggests that delay discounting, which is linked to depression and serotonin function, offers little predictive value for identifying patients at risk of relapse after stopping antidepressant treatment. While delay discounting was elevated in remitted 

and correlated with residual depressive symptoms, it neither changed following antidepressant discontinuation nor predicted relapse over 6 months of follow-up.

“We know that people with a history of depression tend to be more impatient for rewards,” Giles W. Story, PhD, from the University College London, told 

 “And then secondly, [there is] the…separate line of evidence that links depression to changes in serotonin function.”

Giles said the most reliable evidence comes from animal studies showing that serotonergic injections cause animals to be more impatient to get rewards. He predicted that delay discounting could reflect vulnerability to future depression and predict relapse, with greater baseline impatience associated with a greater likelihood of relapse. He also predicted that delay discounting might be a marker of discontinuation.

“In broad brush terms, the idea here is that some people who stop their antidepressants might experience a reduction in serotonin,” Story said.

In a multi-site longitudinal study, investigators examined whether delay discounting, a behavioral measure of impatience for future rewards, could predict relapse after stopping antidepressant medication in patients with remitted MDD. The study, led by Doron Elad, PhD, from Technion-Israel Institute of Technology, and Giles W. Story, PhD, enrolled 97 patients with remitted MDD receiving antidepressant medication (77% female; average age, 34.78 years) and 54 matched healthy controls (70% female; average age, 33.52 years). The study included participants from both Zurich (MDD: 71; controls: 32) and Berlin (MDD: 26; controls: 22).

Using 2 validated delay discounting tasks, investigators measured participants’ preference for immediate versus delayed monetary rewards, with steeper discounting indicating more impatience to wait for symptom improvement. Patients were assessed before and after discontinuation and followed for 6 months to track relapse.

Story explained that delay discounting provides a snapshot of how individuals value the future, offering a behavioral marker that differs conceptually from traditional clinical predictors such as the number of prior episodes or residual symptoms.

“You can think of it as a way [of capturing a] particular point in time somebody's making decisions,” Story said. “In some ways, you could say that's more objective. It's harder to second-guess.”

At baseline, patients with remitted MDD demonstrated significantly steeper discounting than healthy controls (Cohen’s d = 0.34), indicating reduced willingness to wait for future rewards. For example, patients were willing to accept approximately €66 immediately instead of €75 after several weeks, compared with €70 among controls. Baseline discounting was also modestly correlated with depressive symptom severity, even below the clinical threshold for relapse.

Contrary to the study’s primary hypotheses, neither baseline discounting nor early changes following antidepressant discontinuation predicted subsequent relapse. Discontinuation itself did not significantly alter discounting behavior, despite measurable increases in depressive symptoms among those who stopped medication earlier.

The findings suggest that while delay discounting is elevated in remitted depression and reflects residual symptom burden, it does not function as a clinically meaningful predictor of relapse after antidepressant discontinuation.

Elad D, Story GW, Berwian IM, Stephan KE, Walter H, Huys QJM. Delay discounting correlates with depression but does not predict relapse after antidepressant discontinuation. 

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Although patients with remitted MDD showed greater impulsivity than controls, a study found no link between delay discounting and relapse risk after stopping antidepressants.

Giles W. Story, PhD

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