Dissecting the impact of depression on decision-making

Victoria M. Lawlor, Christian A. Webb, Thomas V. Wiecki, Michael J. Frank, Madhukar H Trivedi, Diego A. Pizzagalli, Daniel G. Dillon

Research output: Contribution to journalArticle


BackgroundCognitive deficits in depressed adults may reflect impaired decision-making. To investigate this possibility, we analyzed data from unmedicated adults with Major Depressive Disorder (MDD) and healthy controls as they performed a probabilistic reward task. The Hierarchical Drift Diffusion Model (HDDM) was used to quantify decision-making mechanisms recruited by the task, to determine if any such mechanism was disrupted by depression.MethodsData came from two samples (Study 1: 258 MDD, 36 controls; Study 2: 23 MDD, 25 controls). On each trial, participants indicated which of two similar stimuli was presented; correct identifications were rewarded. Quantile-probability plots and the HDDM quantified the impact of MDD on response times (RT), speed of evidence accumulation (drift rate), and the width of decision thresholds, among other parameters.ResultsRTs were more positively skewed in depressed v. healthy adults, and the HDDM revealed that drift rates were reduced - and decision thresholds were wider - in the MDD groups. This pattern suggests that depressed adults accumulated the evidence needed to make decisions more slowly than controls did.ConclusionsDepressed adults responded slower than controls in both studies, and poorer performance led the MDD group to receive fewer rewards than controls in Study 1. These results did not reflect a sensorimotor deficit but were instead due to sluggish evidence accumulation. Thus, slowed decision-making - not slowed perception or response execution - caused the performance deficit in MDD. If these results generalize to other tasks, they may help explain the broad cognitive deficits seen in depression.

Original languageEnglish (US)
JournalPsychological Medicine
Publication statusPublished - Jan 1 2019



  • Computational modeling
  • decision-making
  • depression
  • drift diffusion model
  • reward

ASJC Scopus subject areas

  • Applied Psychology
  • Psychiatry and Mental health

Cite this

Lawlor, V. M., Webb, C. A., Wiecki, T. V., Frank, M. J., Trivedi, M. H., Pizzagalli, D. A., & Dillon, D. G. (2019). Dissecting the impact of depression on decision-making. Psychological Medicine. https://doi.org/10.1017/S0033291719001570