Scientists have identified a significant chemical in the brain that is key in keeping unwanted thoughts at bay. This discovery could lead to further understanding of mental health problems such as post-traumatic stress disorder (PTSD), anxiety, and even schizophrenia.
Everyone has memories or thoughts that they would rather suppress than think about. These could be in the form of unpleasant memories or images, worries, or even traumatic experiences that bring grief. Sometimes we succeed in suppressing these unwanted thoughts from popping up, but there are unexpected moments they are simply harder to control.
To understand this process of suppressing unwanted thoughts more clearly, participants of the study engaged in a task called "Think/No-Think" where each participant first learned to associate a series of unconnected word pairings. For instance, they were given the word moss, which participants then associated with its unconnected word-pair, north.
In the second part of the task, each was asked to recall the associated word (north) if the cue is green, but to supress the thought of it if the cue is red. For instance, if the word "moss" is shown in green, participants must recall its associated word, north, but if it is shown in red, they must simply stare and supress their minds from thinking of the word "north."
Chemical Responsible For Suppressing Unwanted Thoughts
By using fMRI and magnetic resonance spectroscopy, researchers observed both brain activity and chemistry changes when participants tried to supress their thoughts. As it turns out, a chemical called GABA is the main neurotransmitter responsible for supressing unwanted thoughts and memories. Releasing GABA from a single nerve cell can evidently supress activity in its other connected nerve cells.
Further, researchers found that the concentration of GABA in an individual's hippocampus is predictive of his ability to suppress unwanted thoughts. The hippocampus is a key part of the brain when it comes to memory, while the prefrontal cortex is considered as the command center of the brain. Among the participants, those who had less hippocampal GABA were not quite strong in suppressing the thought as per the prefrontal cortex's commands.
"If an army's foot-soldiers are poorly equipped, then its commanders' orders cannot be implemented well," said Professor Michael Anderson of the University of Cambridge, coauthor of the study.
PTSD, Anxiety, Depression, And Schizophrenia
A striking hallmark of mental health problems such as PTSD, anxiety, and depression is the inability to control negative or unpleasant thoughts from surfacing. In the case of schizophrenia, previous research has shown that those with the disorder have hyperactive hippocampi, and post-mortem analysis of patients shows compromised inhibitory neurons such as GABA. This perhaps contributes to the erratic thoughts and memories and hallucinations among patients.
As the current discovery shows a more specific mechanism involved in memory retrieval and suppression, perhaps experts may be closer to understanding the mechanisms surrounding such mental health problems. Although researchers did not discuss possible specific treatments, their results imply that perhaps stabilizing GABA activity in the hippocampus could prove useful in suppressing unwanted thoughts.
The study was published in Nature Communications.