Researchers have spent over a century trying to solve the puzzle of mental ill-health. Whilst progress has led to advances in the way we treat mental health difficulties, including cognitive behavioural therapy as the leading evidence-based approach (NICE, 2011), the efficacy of current treatments remains limited.

To advance treatments, it has been suggested that greater focus is needed on identifying the core underlying mechanisms which drive psychological problems across mental health disorders and the key therapeutic techniques which can effectively modify them (Chu, Temkin, & Toffey, 2016). Targeting treatment at the level of mechanisms may be more effective because the problem is tackled at its core, rather than manifestations of the problem in the form of symptoms or disorders. This new paradigm necessitates a detailed undertaking to isolate specific mechanisms and the components of treatment which target them.

One such mechanism which has been consistently linked to a range of mental disorders is repetitive negative thinking (RNT; Ehring & Watkins, 2008). RNT is characterised by going over and over negative thoughts in the mind in a way that is unproductive and difficult to control. Capturing the processes of both worry and rumination, research has revealed a consistent link between forms of RNT and depression and anxiety. Findings from experimental and longitudinal studies suggest that increased RNT might be one of the underlying causes of depression and anxiety (Watkins, 2008), indicating that effectively reducing RNT may be an important target for treatment.

This theory was put to test in a recent meta-analysis by Monteregge, Tsagkalidou, Cuijpers, and Spinhoven (2020), which aimed to determine:

1. The overall effect of any treatment on anxiety and RNT outcomes
2. If RNT-focused treatments had larger effects than non-RNT-focused treatments
3. Whether RNT outcomes were correlated with anxiety outcomes
4. Whether any correlation between RNT and anxiety outcomes was stronger for RNT-focused treatments versus non-RNT-focused treatments.

Methods

The authors conducted a systematic review of multiple scientific databases to identify eligible studies published between 1980 and March, 2018. They included randomised controlled trials of any treatment aiming to reduce anxiety in people over the age of 16, which included an outcome measure of RNT and anxiety.

A meta-analysis was conducted on the included studies to determine the effects of treatment compared to the control group immediately following the intervention, and to see if there was an association between RNT and anxiety outcomes. They also compared the effects across different groups of treatments and study characteristics.

Results

Of the 5,812 articles screened, 46 met inclusion criteria for the review. Most of the studies originated from Western countries and included a total of 1,952 participants with a mean age of 41 years.

A broad range of treatments were identified. Twenty-six treatments targeted reductions in RNT specifically, using a range of approaches such as meta-cognitive therapy, attention bias modification or mindfulness. Twenty-nine treatments did not target RNT directly and these typically utilised more general CBT techniques such a problem solving or cognitive restructuring, as well as eight pharmacological treatments.

Key findings

• The overall treatment effect was moderate for both RNT (hedge’s g = 0.68 (95% CI [0.53 to 0.83]) and anxiety outcomes (hedge’s g = 0.63 (95% CI [0.48 to 0.78]), which varied moderately between studies
• The effect sizes were all in the moderate range for different measures of RNT, with slightly higher effects for rumination (hedge’s g = 0.69, 95% CI [0.41 to 0.97]) compared to worry (hedge’s g = 57, 95% CI [0.43 to 0.72])
• The effects of treatments which focused on reducing RNT specifically were comparable to non-RNT focused treatments
• Anxiety outcomes were significantly predicted by RNT outcomes immediately following the intervention (slope coefficient = 0.67, 95% CI [0.45 to 0.90]). This relationship did not differ between the treatment types, suggesting that the association between RNT and anxiety outcomes remained the same regardless of whether RNT was the main target of treatment or not
• Phase III trials had larger effects than phase II trials, which suggests that there are differences in effects depending on the size and scale of the study
• Active treatment as a comparison group had smaller effects than wait-list controls, but was no different to treatment-as-usual
• Interventions with more than eight sessions had larger effects than those with less than eight sessions
• There was no difference in effects for recruitment approach, treatment format, target group, class of disorder, and study quality.

Conclusions

The main conclusion from this review was that all treatments were moderately effective for reducing anxiety and repetitive negative thinking (RNT) in adults with elevated or clinical anxiety, regardless of whether they targeted RNT directly or not. It appears that whilst RNT and anxiety outcomes are related, the treatment type does not seem to make a difference.

Strengths and limitations

This was a very good quality review. The authors utilised a highly systematic and elegant approach to meta-analysis, providing a strong theoretical justification for their approach with carefully chosen research questions that clearly link to the theory they were testing.

The main limitation is that whilst an association between RNT and anxiety outcomes was found, it was not possible to determine if reducing RNT is what caused improvements in anxiety outcomes. The studies were also quite variable, with few examining the same type of treatment. This meant that the power to detect differences between the types of studies was limited and treatments with multiple components made isolating individual effects virtually impossible. Measures of RNT were also mostly limited to those related to worry, which is a particular form of RNT involving negative thoughts concerning feared future events. Therefore, less is known about the impact of these treatments on the broader process of RNT, involving repeatedly getting stuck in negative thoughts of any kind.

Reducing repetitive negative thinking in youth depression and anxiety – my #ActiveIngredientsMH project

Wellcome Trust, a major UK funder for mental health research, recently commissioned 30 research groups around the world to produce an insight report on different ‘active ingredients’ underlying effective treatments for youth depression and anxiety. Following a similar logic in the adult literature, getting to the heart of what causes these problems and isolating the most effective techniques to modify them may advance treatment of mental ill-health in youth. As depression and anxiety are common in young people and typically emerge during adolescence (Kessler et al., 2007), treatment at this early age is important to ensure healthy development and prevent illness progression through to adulthood.

Our report focused on whether reducing RNT is an important part of psychological treatment in youth depression and anxiety. We followed a very similar approach to Monteregge et al. (2020) in our systematic review, identifying randomised controlled trials of any psychological treatments for youth depression and/or anxiety that had included an outcome measure of RNT and depression or anxiety. The difference between our review and Monteregge et al. was:

• A focus on youth between the age of 14 – 24 years
• Examination of treatments for depression and anxiety
• Focus on psychological treatments
• Due to time constraints, we were not able to conduct a meta-analysis (which is currently in preparation)
• We included perspectives from young people with lived experience and clinicians.

The findings were similar. Outcomes for depression, anxiety and RNT showed a similar moderate effect size across all treatments, suggesting an association between these outcomes exists. Further, RNT-focused treatments appeared to show similar moderate effects as non-RNT focused treatments.

There was one important difference in the findings. We also compared different treatment approaches to understand more about what worked and how. We found that psychological treatments which targeted the process of negative thinking (i.e. third wave treatments such as mindfulness and acceptance and commitment therapy; Hayes, 2004) appeared to have larger effect sizes than those which targeted the content of the negative thoughts (i.e. second wave treatments based on traditional cognitive behavioural therapy). Whilst this finding is preliminary and requires confirmation with meta-analysis, it does suggest that the process of RNT is an important target for improving outcomes in youth.

Involving young people and clinicians

A major strength of our approach was that we were able to speak with young people and clinicians about their impressions of RNT in treatment of youth depression and anxiety. They agreed that targeting RNT in treatment is important and suggested that a range of approaches are needed to choose what fits best for the individual. They also suggested that timing and context are important for when and how an intervention is delivered, with a clear desire for support during episodes of RNT.

Clinicians tended to start with traditional CBT techniques such as cognitive restructuring and progressed to process based approaches, such as acceptance and mindfulness, if the negative thoughts were very rigid or based strongly in reality (e.g. death of a loved one).

Implications for practice

The clinical implications of these findings are:

• Reductions in repetitive negative thinking (RNT) are relevant to target in treatment as they appear to be related to improvements in depression and anxiety for both adults and young people
• There are many different ways to reduce RNT, and both targeted and general approaches may be effective. Focusing on improving the process of negative thinking using third wave approaches might be particularly effective in young people.
• Considering there is no one-size-fits all, having a toolbox of techniques and working with the individual to see what works – taking into account their preferences and clinical judgement – are important for treating RNT.

Implications for future research

• More research is needed to isolate and compare different treatment components to see which ones work best
• Trials with mediation analyses across multiple time points are needed to determine whether changes in RNT play a causal role in reducing depression and anxiety
• More research is needed to identify what works best for whom, and more advanced methodologies like ecological momentary assessment and network analysis might help with this
• Developing tools for clinicians and young people to reduce RNT are important, including online and mobile resources that can provide support when RNT is happening in daily life
• More research into third wave approaches are needed (see Horowitz, 2014; Sampson, 2018; )

Final thoughts

The findings from these two studies suggest that reducing repetitive negative thinking (RNT) is important for improving depression and anxiety for both adults and youth, however we don’t know if it causes these improvements and it appears that targeting it directly does not lead to better effects. So, if reducing RNT contributes to improvements in depression and anxiety outcomes, why are treatments which target this directly not more effective? Does this mean it doesn’t matter whether we target mechanisms in treatment or not? In my opinion, it does matter, but the pathways are complex and we still don’t understand them well enough. Developing more targeted and individualised interventions, isolating specific active ingredients to study them more closely, and making sure they are delivered at the right time and place, could be key.

Statement of interests

This work was funded by a Wellcome Trust Mental Health Priority Area ‘Active Ingredients’ commission awarded to Imogen Bell at Orygen and The University of Melbourne.

Links

Primary paper

Monteregge, S., Tsagkalidou, A., Cuijpers, P., & Spinhoven, P. (2020). The effects of different types of treatment for anxiety on repetitive negative thinking: A meta‐analysis. Clinical Psychology: Science and Practice, e12316.

Other references

Chu, B. C., Temkin, A. B., & Toffey, K. (2016). Transdiagnostic mechanisms and treatment for children and adolescents. Oxford, UK: Oxford University Press. https://doi.org/10.1093/oxfordhb/9780199935291.013.10

Ehring, T., & Watkins, E. R. (2008). Repetitive negative thinking as a transdiagnostic process. International Journal of Cognitive Therapy, 1(3), 192-205.

Hayes, S. C. (2004). Acceptance and commitment therapy, relational frame theory, and the third wave of behavioral and cognitive therapies. Behavior therapy, 35(4), 639-665.

Horowitz, M. (2014). Be mindful of the gap: What we know about ‘third wave’ cognitive behavioural therapies compared to other psychological therapies. The Mental Elf

Kessler, R. C., Angermeyer, M., Anthony, J. C., De Graaf, R., Demyttenaere, K., Gasquet, I., . . . Haro, J. M. (2007). Lifetime prevalence and age-of-onset distributions of mental disorders in the World Health Organization’s World Mental Health Survey Initiative. World Psychiatry, 6(3), 168.

Monteregge, S., Tsagkalidou, A., Cuijpers, P., & Spinhoven, P. (2020). The effects of different types of treatment for anxiety on repetitive negative thinking: A meta‐analysis. Clinical Psychology: Science and Practice, e12316.

NICE. (2011). Common mental health disorders: identification and pathways to care.

Sampson, C. (2018). Is third-wave CBT good value? The Mental Elf.

Watkins, E. R. (2008). Constructive and unconstructive repetitive thought. Psychological Bulletin, 134(2), 163.

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