“Learning more about how acute stress and chronic stress affect the brain may help in the identification of treatment targets for depression,” said Jessica Cooper, first author of the study and a post-doctoral fellow in Treadway’s Translational Research in Affective Disorders Laboratory.
‘Adaptive stress response by glutamate was absent in people diagnosed with Major Depressive Disorders (MDD).’
Looking into the brain
The team enrolled 88 participants, including those devoid of mental health issues and patients diagnosed with a major depressive disorder but not under any therapy in the current study. They all were surveyed whether they experienced perceived stress recently in their lives at the start of the study.
Then, they were subjected to a brain-scanning technique known as magnetic resonance spectroscopy. During the scanning process, the participants performed some stressful tasks and submitted their saliva samples under supervision.
The concept behind assigning these tasks is that they mimic acute stressors and trigger a stress response in the body. The controls in the study were healthy individuals.
The levels of glutamate within the medial prefrontal cortex (mPFC glutamate) of the participants were measured using brain scanning both before and after the activities. A stress hormone called cortisol was also measured using the saliva samples received during the scanning process.
The participants were further followed up for four weeks, using a survey protocol, and surveyed about their expected and experienced outcomes for daily activities.
Key findings of the study
The levels of mPFC glutamate decreased after stress tasks when there was a rise of perceived stress in healthy individuals.
This kind of adaptive response by glutamate was absent in people diagnosed with Major Depressive Disorders (MDD).
During the follow-up period, pessimistic characteristics were observed in the people with MDD, who could not experience the above-mentioned adaptive glutamate response.
“To our knowledge, this is the first work to show that glutamate in the human medial prefrontal cortex shows an adaptive habituation to a new stressful experience if someone has recently experienced a lot of stress,” says Michael Treadway, senior author of the study and professor in Emory’s Department of Psychology and Department of Psychiatry and Behavioral Science.
The study, in essence, showed that attenuated glutamate response act as a healthy adaptation to stress. The experts further pointed out how people with depressive disorders suffer from disruptions in normal stress responses, which predisposes them to chronic health problems.
Source: Medindia
