Are Delusions Understandable?

Delusions are defined in DSM-5 as fixed, false beliefs that are not amenable to change in light of conflicting evidence (APA, 2013). Delusions tend to develop on the background of genetic and environmental risk and to go along with severe distress both for the person who holds them and for other people involved. Delusions typically occur in the context of mental disorders and are the most prominent symptom of psychosis.

With the rise of pharmacological treatment in the 1960s, the hope of an easy, cost-effective cure for psychotic symptoms went along with reduced interest in psychological explanations and interventions. It was not until in the last couple of decades that the hope set on pharmacological interventions alone received severe blows after pharma-independent reviews pointed to only moderate effect sizes (Leucht et al., 2012), large numbers of patients who do not take medication as prescribed (Wade, Tai, Awenat, & Haddock, 2017) as well as problematic short- and long-term adverse medication effects (Murray et al., 2016). During these recent decades, psychological models and interventions have been vindicated and continuously further developed. One of the most promising approaches has been the adaptation of cognitive behavioral therapy (CBT) for depression to treating delusions. In this approach, delusions – along with other potentially unhelpful beliefs about the self and others – are framed within a cognitive model and one of the aims is to reduce distress by gently reviewing the evidence in favor of these beliefs (Kuipers, 1996).

Although the early pioneers in this approach were faced with numerous concerns, including the worry that talking with patients about their delusions would only make matters worse, we now know that cognitive behavioral interventions are helpful in reducing delusional conviction and distress (van der Gaag, Valmaggia, & Smit, 2014). Nevertheless, the effect sizes leave room for improvement. A step toward improved interventions would be to arrive at a better understanding of the mechanisms that contribute to the formation and maintenance of delusions. Building on research pointing to the relevance of several psychological mechanisms, such as emotion regulation, reasoning biases (e.g., the tendency to “jump to conclusions” or to stick with a favored interpretation), and processing of self-relevant information, some researchers have proposed that it could be beneficial to take a causal-interventionist approach (Freeman, 2011) and focus interventions more explicitly on these mechanisms. In this sense I am happy to bring together research from across the world in this topical issue of the Zeitschrift für Psychologie, research that focuses both on the challenge of improving our understanding of the psychological mechanisms that underlie delusions and on psychological interventions that can be derived from this knowledge.

This issue opens with a review of intervention studies that have taken a causal-interventionist approach and have focused on ameliorating affective states and affect regulation in people with delusions (Opoka, Ludwig, & Lincoln, 2018). On the background of numerous experimental and experience sampling studies showing that delusions are preceded and accompanied by negative affect, the authors posited that interventions that are successful in improving affect would have the potential to reduce delusions without even targeting delusions explicitly.

The following two contributions also focus on mechanisms of change within interventions aimed at reducing delusions. Mehl, Schlier, and Lincoln (2018) report on a mediation analysis of a CBT for psychosis (CBTp) effectiveness trial in which delusions were a secondary outcome. They tested whether CBTp unfolds its effects on delusions by reducing reasoning biases and dysfunctional self-schemas. However, the intervention effects were not mediated by the proposed mechanisms, indicating that more specific interventions may be necessary to target these putative mechanisms.

This assumption is confirmed in the contribution by Schneider, Cludius, Lutz, Moritz, and Rubel (2018), who take a closer look at the active components of the Metacognitive Training for Psychosis, a group training program that also takes a causal-interventionist approach by targeting reasoning biases. The authors found that modules addressing the jumping to conclusions bias and the bias against disconfirmatory evidence (BADE – meaning the tendency to stick with a favored interpretation and be less receptive of information that does not support this interpretation) were associated with reductions in the respective biases, indicating that the training is successful in targeting these biases.

The next two contributions take a closer look at reasoning biases and at issues related to their assessment. The article by Luk, Underhill, and Woodward (2018) investigates whether the BADE is specifically linked to delusions by exploring the component structure in the BADE task measures that is predictable from symptoms in a large sample of participants with a diagnosis of schizophrenia or schizoaffective disorder. A component reflecting evidence integration emerged, which was predicted by delusions but also by thought disorder. This article is nicely complemented by the Research Spotlight by Howe, Ross, McKay, and Balzan (2018), who investigate a seeming paradox between findings from a variant of the paradigm used to assess jumping to conclusions and one to assess BADE and conclude that the task instructions need to be rephrased.

Similar to Opoka et al. (2018), the next Research Spotlight by Clamor and Krkovic (2018) builds on the premise that delusions arise as a function of negative affect – however, interestingly, the authors propose that delusions may serve as a short-term means to achieve stress relief. They tested this assumption by relating the subjective and psychophysiological post-stressor responses to the extent that participants respond to a stressor with increases in paranoia and found partial support for their hypothesis. If this innovative assumption can be further corroborated across different developmental stages of delusions it could promote an entirely different approach to treating delusions, in which learning mechanisms play a more prominent role.

A related perspective is taken by Westermann, Gantenbein, Caspar, and Cavelti (2018). They elaborate on the idea that delusions could be an adaptive attempt to satisfy and protect psychological needs, such as the need for affiliation, orientation, and control, or the need for self-esteem. They also devise conclusions for case formulations, therapy planning, and therapeutic relationship building based on this idea.

Taken together, the contributions in this issue are a timely reflection of the ongoing struggle to gain a better understanding of what causes and maintains delusions and how to improve their treatment. The contributions also mirror the specificity and level of detail that research in this area has now reached. Although none of the contributions on its own is likely to provide a breakthrough in our understanding of delusions, taken together they add to paving the way toward this aim. If there is any chance of achieving a quantum leap in the way we understand and deal with delusions, it may lie in combining not only the different mechanisms discussed here but also the different levels of explanation (biological, social, psychological) within novel and testable comprehensive models that could then be used to derive individualized interventions. It will be exiting to further witness the progress in this field over the coming decades.