The Neurobiology of Anhedonia

In simple terms anhedonia is an important symptom of depression. The DSM IV states that individuals having this anhedonia “may report feeling less interest in hobbies, ‘not caring anymore,’ or not feeling any enjoyment in activities that were previously considered pleasurable”. For the diagnosis of depression either this symptom or low mood is required together with four other features of the disease. Anhedonia is a decrease in motivation as well as reduction in experienced pleasure. Anhedonia has a motivational as well as hedonic aspect. This makes it difficult to translate findings from animal models or other neuroscience research to patient characteristics or treatment. In other words a simple translation from reward or pleasure by the dopamine system and a reduction of dopaminergic transmission as explanation of anhedonia is to simple.

The authors of an extensive review on the translational aspects of anhedonia also pose the option to add the lack of decision making as another aspect of anhedonia.

For example, one could describe motivational anhedonia as either a general feeling that it is not worth getting out of bed, or a string of finite choices between staying in bed and some other activity in which an MDD patient consistently chooses the former. From this perspective, the clinical phenomenon of anhedonia can be seen to emerge from a succession of individual decisions.

They suggest to use a distinction in motivational anhedonia and consummatory anhedonia. This distinction should be used to modify psychiatric interviews. The suggested subdivision with decisional anhedonia is not easily implemented in psychiatric interviews but should be measured by decision making experiments as suggested by the authors. To my opinion this last feature is dragged into the model since it’s importance in neurobiological and animal research. The first distinction is clinically recognizable and relevant to my opinion. What do you think?
Treadway, M., & Zald, D. (2011). Reconsidering anhedonia in depression: Lessons from translational neuroscience Neuroscience & Biobehavioral Reviews, 35 (3), 537-555 DOI: 10.1016/j.neubiorev.2010.06.006