Delay Discounting Fails to Predict Antidepressant Relapse in MDD
Key Clinical Summary
- Relapse risk remains high: About one-third of patients with major depressive disorder (MDD) relapse within 6 months of antidepressant medication discontinuation.
- Delay discounting elevated but not predictive: Patients with remitted MDD showed higher delay discounting than controls, but this did not predict relapse after stopping antidepressant medication.
- Limited prognostic utility: Neither baseline delay discounting nor early changes following antidepressant discontinuation were associated with depressive relapse.
A new multi-site study published in Molecular Psychiatry suggests that while delay discounting is elevated in patients with remitted major depressive disorder (MDD), it neither changes after antidepressant medication discontinuation nor predicts subsequent depressive relapse, limiting its clinical utility as a prognostic tool.
Study Findings
The study enrolled 97 adults with remitted MDD who were receiving antidepressant medication and planning discontinuation, along with 54 matched controls without a lifetime history of MDD. Delay discounting was measured at baseline and again within 6 months after antidepressant discontinuation in the MDD group, with participants followed for depressive relapse over 6 months.
At baseline, individuals with remitted MDD demonstrated significantly higher delay discounting compared with controls (p < 0.05; Cohen’s d = 0.34). Higher discounting, which reflected a stronger preference for smaller immediate rewards over larger delayed ones, was also modestly correlated with greater depressive symptom severity (Spearman ρ = 0.24).
Despite these baseline differences, delay discounting did not significantly change after antidepressant discontinuation. Predictive modeling showed that neither baseline delay discounting nor early changes after stopping medication were associated with subsequent depressive relapse during the 6-month follow-up.
Clinical Implications
For mental health care providers managing antidepressant discontinuation in patients with remitted MDD, these findings suggest that delay discounting has limited value as a prognostic tool. Although elevated delay discounting may reflect residual, sub-clinical features of depression, it does not appear to track illness trajectory during medication withdrawal.
Though behavioral markers linked to serotonergic function, such as delay discounting, have been hypothesized as accessible predictors of relapse risk, the absence of predictive utility in this study indicates that clinicians should be cautious about relying on reward-based decision-making measures when assessing relapse vulnerability.
The findings also underscore the complexity of depressive relapse mechanisms, which may not be captured by single behavioral constructs.
Expert Commentary
The researchers acknowledged that the study’s limited 6-month follow-up period may have impacted their ability to accurately predict risk of relapse, as some patients may have relapsed outside of the follow-up window. “Nevertheless, our null finding suggests that, if discounting is indeed a trait-level vulnerability factor for MDD, this effect is too small to be clinically meaningful over short-term follow up,” concluded Doron Elad, PhD, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel, and study coauthors.
