Zulkayda Mamat is no stranger to traumatic memories. Ethnically Uighur, Mamat left China at age 12 after an uprising in the region of East Turkestan, where most of Mamat’s extended family still lives. More than one million Uighurs have been arbitrarily detained in “political education” camps and prisons. “I know people in camps. I have witnessed families completely broken down, people in the diaspora, their entire lives changed,” says Mamat, who just received her doctorate in cognitive neuroscience from the University of Cambridge.
Over the years, Mamat has noticed how the most resilient Uighurs she knows manage to cope with their trauma. Their formula is simple: they push the distressing memories out of their mind. Mamat herself is good at this. “It’s almost intuitive to be able to control my thoughts,” she says.
Clinical psychologists often warn against suppressing thoughts because they believe distressing ideas and images will bubble up later with greater frequency and worsen mental health problems. Psychoanalysis focuses on the contrasting approach of hunting down and exploring the meaning of any thoughts a person might have pushed to the back of their mind.
But Mamat now has data to support her intuition that suppression is beneficial. In a September 20 paper in Science Advances, she and her adviser, cognitive neuroscientist Michael Anderson, report that they successfully trained people—many of whom had mental health problems—to suppress their fears and that doing so improved these individuals’ mental health. “Suppressing negative thoughts, far from being a hazardous thing to do,” Anderson says, “actually seemed to be of great benefit, especially to the people who need it the most—people suffering from depression, anxiety and post-traumatic stress.”
The work also calls into question whether people with mental health disorders have an inherent inability to suppress intrusive thoughts. “It’s probably not a deficit,” Mamat says. The vast majority of people in the study, she says, “were surprised to see that this was something they could learn.”
The technique bears a likeness to behavioral therapies in which people expose themselves to cues or situations that trigger fear and anxiety—heights, dirt or parties, say—until the brain learns to inhibit those fear responses, says Charan Ranganath, a cognitive neuroscientist at the University of California, Davis, who was not involved in the research. But learning to halt the thoughts that arise from those cues is a novel approach. “What’s surprising to me is telling people to stop that thought in and of itself is effective,” Ranganath says. “That’s an idea that could be really useful to bring into therapies.”
Not everyone agrees that the approach is safe or likely to be successful as a therapeutic tool. But if further research suggests it is, suppression training might either be used alone or in conjunction with, say, cognitive-behavioral or exposure therapy, Anderson suggests.
The new findings stand in stark contrast to the conventional wisdom that thought suppression is both ineffective and harmful as a therapeutic approach. In the 1980s psychologist Daniel Wegner popularized this idea with his “white bear” experiments. In these studies, people were instructed not to think about a white bear. And in following those instructions, they later thought about white bears more often than did participants in a control group who had been initially told to think about the animals. Trying not to think about something, Wegner concluded, causes those same thoughts to pop up more often.
The idea has been influential in clinical psychology. Anderson and his colleagues, however, have generated data spanning two decades that suggest that pushing away negative memories causes those memories to fade and become less distressing. His experiments are meant to mimic a real-world scenario in which people encounter reminders of worrying thoughts and then need to decide whether to stem those thoughts or dwell on them.
Previously Anderson had not directly tested whether his technique, which he calls retrieval suppression, could be useful as a therapy. One potential problem was that the people with mental health conditions, who could benefit most from such a therapy, might be incapable of practicing it because of the way their brain functioned. Some data supported that idea, but Mamat was not convinced it was true. She thought anyone might be able to learn to stem their thoughts if they were shown how.
In March 2020 she decided to find out. COVID had halted all in-person research, including the brain-imaging project Mamat had been pursuing. It had also spawned a wave of anxiety, depression and other mental health problems that needed to be addressed. Mamat told Anderson she wanted to test a therapy involving suppression that she could administer online from her apartment.
She cast a wide net for participants. English-speaking adults could volunteer as long as they were not color blind and did not have a neurological disorder or reading disability—and many of the volunteers did have mental health problems. Of the 120 people from 16 countries who participated in the study, 43 percent had clinically concerning levels of anxiety, 18 percent had significant depressive symptoms and 24 percent had probable post-traumatic stress disorder (PTSD).
Before the training, Mamat asked each person to generate thoughts on which to base a set of cue words: 20 specific worries and fears that repeatedly intruded on their thoughts, 36 neutral events and 20 wishes for the future. As part of the study, the researchers took assessments of the participants’ anxiety, depression, worry and well-being.
Over three days, 61 of the participants were exposed to the cue words that represented their fears. For example, if someone was afraid that their parents would be hospitalized with COVID, the cue word might be “hospital.” During training, they were instructed to stare at the reminder for several seconds and acknowledge the event but then to shut down all thoughts about it, as well as any associated imagery. If thoughts, feelings or images did spring to mind, participants were to immediately push those ideas out of awareness and return their attention to the reminder. They were not to generate distracting thoughts because the researchers did not want any type of avoidance to be part of the strategy. A control group of 59 people were instructed to do the same for neutral events such as being seen by an optician.
In other trials, participants were told to conjure imagery to embellish and elaborate either neutral or positive events. The two groups suppressed each fear or neutral event or imagined each hope or neutral event 12 times each day for three days and were then tested on both the vividness and emotional impact of their thoughts.
As expected, suppression diminished the vividness and intensity of the fears. As a group, participants recalled details of their personal fears or neutral events less often and experienced reduced anxiety related to those fears.
More notably, suppressing fears improved people’s mental health and did so much more than suppressing neutral scenarios. Worry, depression and anxiety were all significantly reduced, and well-being increased. “What the training seems to be doing is giving people a way to stop from going into this vortex of worry when a negative thought comes up,” Ranganath says. Surprisingly, imagining positive events produced no mental health benefits, suggesting that generating positive thoughts has far less power than blocking negative thoughts, Anderson says.
The researchers also showed that suppression did not lead memories to rebound, as the white bear experiments might suggest. Although there were individuals whose anxiety or depression worsened after training, there were fewer such cases in the group suppressing thoughts of feared events than among individuals who were blocking out neutral events. The researchers “went above and beyond” to demonstrate that the therapy did not have adverse effects, Ranganath says.
Three months after the training, depression scores continued to decline for the group as a whole. On measures of anxiety, worry and PTSD, however, the effects of the training were only apparent among the people who had been depressed or anxious or showed signs of PTSD at the start of the study. “The people who were suffering at the outset showed a consistent benefit,” Anderson says.
It appears that the more symptomatic a person had been, the more likely they were to use suppression after training, apparently because they found it useful. (No one was told to practice the technique after the three-day training period.) Among those with probable PTSD, for example, 82 percent reported reduced anxiety, and 63 percent said their mood improved—changes they attributed to suppression. “It’s the people who were suffering at the outset who saw how much suppression benefited them,” Anderson says.
Participants also reported that the training improved their ability to suppress thoughts; they rated their skill on the third day as much higher than they did on the first. Three quarters of the participants described being surprised or very surprised by their newfound faculty. “I couldn’t believe how effective it was, and it made me realize how powerful my brain can be,” one participant wrote.
The strategy has also drawn criticism, however. “[The paper] may lead some people to conclude that they should practice suppressing memories of a recent traumatic event, which, research suggests, may actually increase their risk of developing posttraumatic stress disorder,” says Amanda Draheim, a psychologist at Goucher College in Baltimore.
Fully vetting the technique requires a randomized controlled clinical trial with several hundred participants, something Anderson has in his sights. Mamat has developed a phone app that could be used in such a trial, and she hopes it will eventually be available for widespread use.
During her study, Mamat got to know the participants, talking to them for hours from her apartment over Zoom. One of them broke down in tears and told Mamat that the experience had changed her life. Another described suppression as a “power” and planned to teach it to her children. The personal feedback convinced Mamat that the experiment was worthwhile, no matter what the data showed. “That was enough for me to have done this entire thing,” she says. “That was beautiful. That was really beautiful.”
