Cognitive effort-based decision-making in major depressive disorder.

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• The relationship between major depressive disorder (MDD) and the motivation to invest cognitive effort for rewards remains unclear.
• Previous studies on cognitive effort-based decision-making are limited by confounds like physical effort and temporal delay discounting.

Purpose of the Study:

• To develop and utilize a novel task, the Cognitive Effort Motivation Task, to specifically assess willingness to exert cognitive effort for rewards.
• To investigate cognitive effort motivation in individuals with MDD compared to healthy controls, free from confounding variables.

Main Methods:

• Developed the Cognitive Effort Motivation Task, manipulating cognitive effort by varying spatial working memory load (1-5 items).
• Administered the task to 26 patients with MDD and 44 healthy controls, involving extensive training and choice-based reward scenarios.
• Employed computational modeling to analyze decision-making patterns related to effort and reward devaluation.

Main Results:

• Both groups perceived increased cognitive effort with higher task demands, maintaining high accuracy (>80% training, >95% task).
• Computational modeling indicated a parabolic relationship, where higher effort levels disproportionately devalued rewards.
• Major depressive disorder patients exhibited steeper reward discounting by effort and lower willingness to exert cognitive effort than healthy participants.

Conclusions:

• Depressed patients demonstrate impaired cognitive effort motivation compared to the general population.
• The findings provide empirical evidence of this impairment, isolated from other confounding variables.