Major depressive disorder — also known as clinical depression — is a severe illness that affects an individual in many different ways.
The disorder is characterized by sadness, poor concentration, impaired decision-making and an inability to cope. An individual’s ability to experience pleasurable emotion can be impaired, replaced with prolonged negative thoughts and feelings.
New research, using functional magnetic resonance imaging (fMRI), gives scientists a view of how the brain changes during depression.
The findings, published in the journal Biology of Mood & Anxiety Disorders, show that a depressed brain is characterized by abnormal nerve connectivity.
Researchers from Stanford University compared the fMRI scans of women who were resting (but still awake). Half of the women were diagnosed with depression at the time of the scan and the other group consisted of women who had never had severe depression.
fMRI measures changes in blood flow, and by overlaying images of depressed and unaffected brains, a number of differences came to light.
The images showed that the depressed had decreased connectivity between several key regions of the brain responsible for emotional behavior, learning, memory and decision making.
“In addition to decreased connectivity between emotion processing regions of the brain, we found that depression was linked to an increase in connectivity between the dorsal caudate and an area of the prefrontal cortex,” said lead researcher Daniella Furman, a doctoral student in psychology.
“Deep within the brain, the caudate is thought to be involved in learning, motivation, and emotion while the prefrontal cortex at the front of the head is involved in maintaining goals and likely regulating emotional behavior. Together, these regions may act to filter out irrelevant thoughts or actions.”
Researchers believe greater connectivity may limit the depressed from updating their working memory and, as a result, have sustained negative thoughts.
Source: Biomed Central