For years, psychologists have argued that suppressing thoughts can often backfire, sometimes even making them more persistent and intrusive. However, recent research challenges this notion, and suggests that suppressing negative thoughts might actually be beneficial for mental health.

A recent study, published in the journal Science Advances and led by Dr. Michael Anderson and Dr. Zulkayda Mamat, indicated that training the brain to block out negative thoughts could improve symptoms of anxiety, depression, and post-traumatic stress disorder (PTSD).

The study found that participants, who had high anxiety levels and had suppressed their negative thoughts, saw a 44% decrease in self-reported worries. Meanwhile, participants with PTSD saw their overall negative mental health symptoms decrease by 16%, while positive mental health increased by nearly 10%.

The study involved 120 participants from 16 countries, each tasked with listing 20 fears about potential future events, 20 hopes, and 36 neutral events. These fears were not generic, but recurring, distressing thoughts.

The participants also completed questionnaires to assess their mental health, allowing the researchers to observe the impact of the study on a broad range of participants with varying conditions, including many with serious depression, anxiety, and PTSD.

The participants were asked to associate a cue word (an obvious reminder that could be used to evoke the event during training) and a key detail (a single word expressing a central occurrence) with each type of event. For example, the word "hospital" was associated with the fear of parents getting severely sick from COVID-19 and the detail was "breathing."

Each event had to be unique to the participant, and something they had vividly imagined happening. The participants were asked to assess and rate each event on several factors, including how vivid it was, the likelihood of its occurrence, when it might happen, how it made them feel (anxious for negative events or joyful for positive ones), how often they thought about it, degree of current concern, its long-term impact, and how emotional intense it was for them.

Half of the participants were instructed to focus on one of the negative words, without thinking about the others. The other half did the same, but with neutral words. The exercise was repeated 12 times daily for three days.

"You're told: If something does pop into mind, even briefly, push it out," Dr. Anderson, a cognitive neuroscientist at the University of Cambridge, said. "Moreover, don't distract yourself. Don't think about lunch."

At the end of the study, both immediately and after three months, participants reported suppressed events were less vivid and less fearful. They also found themselves thinking about these events less.

Moreover, the participants of the group that blocked out negative thoughts not only reported experiencing less vivid fears, but also improved mental health when compared to the group which suppressed neutral thoughts.

"It was very clear that those events that participants practiced suppressing were less vivid, less emotionally anxiety-inducing, than the other events and that overall, participants improved in terms of their mental health. But we saw the biggest effect among those participants who were given practice at suppressing fearful, rather than neutral, thoughts," said Dr. Mamat, who was a PhD student in Anderson's lab and at Trinity College, Cambridge, during the study.

"The people with the highest trait anxiety and the highest PTSD were the ones that benefited the most," said Dr. Anderson.

He further noted that no instances of increases in negative symptoms were caused by this intervention.

Furthermore, suppressing negative thoughts seemed to prevent participants' mental health from worsening over time, with approximately 80% of participants choosing to voluntarily continue using the thought suppression techniques post-study in their daily lives.

Dr. Anderson believes that training the brain to block negative thoughts could be a valuable tool in treating anxiety, depression, and PTSD, both in therapy and at home.

"Although more work will be needed to confirm the findings, it seems like it is possible and could even be potentially beneficial to actively suppress our fearful thoughts," he added.