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Dissecting the impact of depression on decision-making.

Authors
  • Lawlor, Victoria M1, 2
  • Webb, Christian A1
  • Wiecki, Thomas V3
  • Frank, Michael J4
  • Trivedi, Madhukar5
  • Pizzagalli, Diego A1
  • Dillon, Daniel G1
  • 1 Center for Depression, Anxiety and Stress Research, McLean Hospital/Harvard Medical School, Belmont, Massachusetts, USA.
  • 2 Emory University, Atlanta, Georgia, USA. , (Georgia)
  • 3 Quantopian, Inc, Boston, Massachusetts, USA.
  • 4 Brown University, Providence, Rhode Island, USA.
  • 5 UT Southwestern Medical Center, Dallas, Texas, USA.
Type
Published Article
Journal
Psychological Medicine
Publisher
Cambridge University Press
Publication Date
Jul 01, 2020
Volume
50
Issue
10
Pages
1613–1622
Identifiers
DOI: 10.1017/S0033291719001570
PMID: 31280757
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Cognitive 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. Data 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. RTs 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. Depressed 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.

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