Diminished reward processing in brain circuits may be contribute to adolescent depression and early life stress.
Duke University and University of Texas Health Sciences Center at San Antonio researchers enrolled 106 adolescents, aged between 11 and 16 years old. They received an MRI scan, as well as assessments of mood and neglect. Two years later, they had another brain scan.
The researchers focused on the ventral striatum, an area of the brain that is crucial for processing rewarding experiences and creating positive emotions. Over the two-year study period, adolescents who had been emotionally neglected were found to have an unusual reduction in the response of the ventral striatum to rewards, the researchers reported in the journal Biological Psychiatry.
This study appears to suggest that early life stress in some people may alter the brain’s ability to experience enthusiasm or pleasure. Also, this stress may increase over time so that people who are resilent when they are younger could develop problems later in life.
“Our work is consistent with other recent studies finding deficient reward processing in depression, and further underscores the importance of considering such developmental pathways in efforts to protect individuals exposed to childhood adversity from later depression,” Jamie Hanson, PhD, of Duke University said in a statement.
Early life stress is a major risk factor for later episodes of depression. In fact, adults who are abused or neglected as children are almost twice as likely to experience depression.
Scientific research into this link has revealed that the increased risk following such childhood adversity is associated with sensitization of the brain circuits involved with processing threat and driving the stress response. More recently, research has begun to demonstrate that in parallel to this stress sensitization, there may also be diminished processing of reward in the brain and associated reductions in a person’s ability to experience positive emotions.