Author Interviews, Depression, JAMA / 06.07.2017
Study Helps Explains Why Dopamine Drugs Not Effective For Depression
MedicalResearch.com Interview with:
Robb B. Rutledge, PhD
Max Planck University College London Centre for Computational Psychiatry
and Ageing Research
University College London
London, England
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Depression is associated with deficits in how the brain responds to rewards, something the neurotransmitter dopamine is strongly implicated in.
Dopamine represents what is called a reward prediction error, the difference between experienced and predicted reward. This error signal is used for learning. For example, if the outcome of a decision is better than expected, you can update your expectations using this error signal and you should expect more next time. Previous research has shown that depression reduces these signals in the brain when people are learning about the world around them. We designed a task where participants did not have to learn anything during the experiment and we found that in this situation reward prediction error signals were not affected by depression. The signals we measured in the ventral striatum, a brain area with a lot of input from the dopamine neurons, looked the same in depressed and non-depressed individuals. We also found that the emotional impacts of reward prediction errors were similar in depressed and non-depressed individuals when we eliminated the need for learning during the task in both the lab and using a smartphone experiment with 1833 participants.
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