Most of us have probably spent many a night up late, re-playing an awkward moment that happened ten years ago over and over again in our heads. Why did I say that, we think, of the time a waiter said “Enjoy your meal” and you replied, “You too.” But for some people, these intrusive, negative thoughts take a turn to the far more serious, and come up not just when your mind is drifting as you’re trying to fall asleep, but any waking moment of the day. New mothers holding their babies, unable to stop thinking about why would happen if they dropped them; or people who live with PTSD, flashing back to the scene of their trauma. For many people, whether living with mental health issues or not, being able to stop intrusive thoughts could be a major breakthrough in their quality of life. Recently, scientists have identified the mechanism that keeps unwanted thoughts at bay in the brain itself, suggesting that new hope might be on the horizon.
Researchers at the University of Cambridge in the UK wanted to study how intrusive thoughts get caught in a loop in the brain. They had twenty-four young adult subjects participate in what’s called a “Think/No-Think” procedure, and looked at their brains using fMRI imaging. During the procedure, the researchers taught the subjects to associate two words with each other, which otherwise had no obvious associations, like “ordeal” and “roach.” (Though, IMO, I would absolutely associate roaches with an ordeal, but I guess these researchers have never lived in New York.) The researchers then asked the subjects to recall the paired word if the original word was green, or suppress the recall if the word was red; that is, if “ordeal” showed up in green, they could think of the word “roach,” but if “ordeal” showed up in red, they had to try to suppress the thought and think of other words.
The test showed that there’s one particular neurotransmitter, called GABA, that is particularly abundant in the brains of people who were able to suppress the association. When there was lots of GABA in the subjects’ hippocampi — the area of the brain that controls memory — it predicted whether or not the subject was able to suppress the word association, implying that they would, too, be better at suppressing unwanted thoughts. By contrast, people with less GABA in their hippocampus had a tougher time suppressing the association.
This finding is really important because it helps us understand the mechanisms behind illnesses that can cause intrusive thoughts. Whereas before, research focused on the prefrontal cortex in the brain, this research shows that there are more areas of the brain that need to be studied in order to fully understand the connection.
"Our ability to control our thoughts is fundamental to our wellbeing," Professor Michael Anderson said in a press release."When this capacity breaks down, it causes some of the most debilitating symptoms of psychiatric diseases: intrusive memories, images, hallucinations, ruminations, and pathological and persistent worries. These are all key symptoms of mental illnesses such as PTSD, schizophrenia, depression, and anxiety.”
Lots of people would love to be able to control their thoughts, but the implications of it are a little scary, to say the least. In the 2004 movie Eternal Sunshine of the Spotless Mind, a woman undergoes an experimental treatment to erase bad memories of a failed relationship. The effects are, well, kind of devastating. While this experiment in no way looked at the science-fiction feasibility of erasing memories, nor did it explore any kind of treatment possibilities, it still asks the question: Would you choose to stop suppress certain memories?
For people for whom intrusive thoughts are a debilitating aspect of everyday life, the answer might be an unequivocal yes; I know in my past struggles with anxiety, obsessive, unwanted thoughts were the single biggest drain on my mental health day in and day out. This experiment, in helping us understand the pathways of intrusive thoughts, offers hope for folks whose recurring memories actively sabotage their ability to heal.