Many of us have thought so for a long time but science is finally backing up our observations with cold, hard studies.
Let’s take depression.
Anhedonia – or the loss of pleasure or reward, is one of the hallmarks of depression.
For years, scholars have debated the cause of anhedonia. Is it a reduced ability to feel pleasure or is it more of an inability to sustain pleasure over a long time?
To look at this issue, University of Wisconsin researcher Richard J. Davidson, PhD and his laboratory took functional magnetic resonance images (fMRI) of 27 depressed individuals and 19 control participants.
During the course of the 37-minute fMRI, two groups of participants were shown positive and negative images. Those in the first group were told to try “enhancing” or “suppressing” their emotional responses, an exercise in which they had been previously trained.
The second group of participants was told to simply pay attention to the images as they normally would without enhancing or suppressing their emotions.
Participants also used self-reporting tools to measure the intensity of their emotions.
Depressed individuals showed a specific decrease in activation in the nucleus accumbens (part of the reward center of the brain) across time, while control subjects maintained their level of activation.
Overall, it was more difficult for depressed patients to sustain nucleus accumbens (NAcc) engagement when presented with positive images that should have caused positive emotions.
This decrease in activity paralleled the self-report of depressed participants – not only was brain activity down, but participants confirmed that they felt less positive as well.
Davidson et al. concluded that the loss of pleasure may result from an inability to sustain activity in the fronto-striatal network leading to problems processing rewards and a reduction in positive affect.
You can read the entire study in the December 2009 volume of Proceedings of the National Academy of Sciences USA.
Please keep in mind that because this was not a randomized study (how would you randomize depression?) we need to be careful when drawing conclusions.
However, investigators attempted to manage this by recruiting a control group (matched for gender and age) of people who were not depressed.
This is just one example of the interconnected nature of emotions and the brain. To find out other examples, check out our series on New Brain Science.
Does having brain research like this help you explain diagnoses and treatments to patient? Please leave a comment below.