Scoping review of episodic future thinking and delay discounting observed in Alzheimer’s disease, depression, and PTSD

Delay discounting (DD), the decrease in the subjective value of a reward as its receipt is delayed, is associated with a variety of risky health behaviors. Episodic Future Thinking (EFT), the capacity to imagine events that might occur in the future, is understood as a reliable intervention in reducing DD. While populations known to exhibit heightened DD rates may benefit from EFT-based interventions, impaired capacity for EFT may reduce their effectiveness. This scoping review examines the available evidence regarding the co-occurrence of steep DD rates and impoverished EFT across Alzheimer's disease (AD), post-traumatic stress disorder (PTSD), and depression to inform the transdiagnostic potential of EFT-based interventions. Searching and screening of articles were conducted on PsycINFO, PubMed, and Medline in February of 2025 following PRISMA guidelines. Across all disorders, clinical populations exhibited steeper DD rates, as well as impaired EFT characterized by marked reductions in specificity, detail, and novelty of the imagery. Cross-disorder comparisons highlighted reduced memory specificity impacting future simulation and physiological abnormalities in the hippocampus and vmPFC as potentially shared mechanisms in DD and EFT deficits. Despite a consistent pattern of steep DD and impoverished EFT occurring in each population and potentially influenced by similar mechanisms, the lack of studies examining DD and EFT in the same sample limits our conclusion and highlights where further research is warranted.