Does depression affect how our brains respond to rewards?
Basic reward processing is surprisingly intact in people with major depression. Reward prediction errors represent the difference between what we get and what we expected to get, and we use these signals (linked to dopamine) to learn about the world around us. Major depression has been associated with a reduced impact of reward prediction errors on neural and emotional measurements in tasks where subjects have to learn associations between cues and rewards. However, we found that, in tasks that do not require significant learning, reward prediction errors have similar impacts on the brain and on mood in depressed and non-depressed subjects. Our results were shown using brain scanning in the lab and in 1,833 players of our smartphone app, ‘The Great Brain Experiment’. These results suggest that the dopamine system that produces reward prediction errors is probably functioning normally in depression and that the reward-related symptoms of depression have a different cause.
Rutledge RB, Moutoussis M, Smittenaar P, Zeidman P, Taylor T, Hrynkiewicz L, Lam J, Skandali N, Siegel JZ, Ousdal OT, Prabhu G, Dayan P, Fonagy P, Dolan RJ. (2017) Association of neural and emotional impacts of reward prediction errors with major depression. JAMA Psychiatry 74, 1-8. [Abstract] [PDF] [Supplemental] [Commentary]