What is inside the treatment?

Most psychotherapies are complex, composite treatments. A variety of elements are integrated, often without clear or evidence-based rules as to why each element was selected and for what purpose. This is because a 'system' of psychotherapy is founded on a theoretical model explaining how psychopathology emerges and is maintained, as well as how it can be treated.

The model is often idiosyncratically crafted by the treatment developer(s), heavily filtered by their own culture and interests. A treatment 'package' is more circumscribed to a particular disorder and involves case formulations, treatment steps and techniques employed. Here too, how these elements are selected and assembled hinges on the subjectivity of the treatment developer, such as their interpretation of clinical cases or research studies.

Once psychological treatments are developed, clinical studies are conducted to assess whether these benefit patients with a particular symptom or disorder. This is similar to what happens for other medical interventions, for example, drugs. But the crucial difference is that we know very little about the 'ingredients' that compose a psychotherapy treatment or package. For example, for a drug like Respillin (Amoxicillin), a widely used antibiotic, we can consult the package insert.

We know the active ingredients – those responsible for the drug's mechanism of action. We also know which other elements are included and how each contributes to the drug's overall effect (for example, to support assimilation of the active ingredient, or to counter side effects). We examine interactions between the drug and the organism in both directions: how the drug affects the organism (i.e. pharmacodynamics) and how, in turn, the organism affects the drug (i.e. pharmacokinetics).

In contrast, for psychotherapies, we employ a perspective that uses the treatment brand or package as a unit of analysis. It is from this vantage point that we try to identify mechanisms of action or patient characteristics that would predict response. 

But there are important drawbacks to moving forward in this way. 

First, we know very little about the ingredients inside a psychological treatment package. For most interventions, we know some of the components, but we rarely have a complete list. Relatedly, packages with different theoretical underpinnings frequently operate with entirely different languages, even if they may be dealing with identical or overlapping concepts, just labelled differently. 

Second, we have very little information about what each component does; whether it is key to the therapy's mechanism of action, plays an adjunctive role, or no role at all; whether and to what degree it contributes positively or negatively to the overall effects of the package; whether the effects of components are additive or synergistic; whether a component enhances or dampens the effects of another. This information gap also limits our quest to identify the mechanisms by which psychotherapies carry their effects: if we are not sure of what is inside the treatment, how can we try to understand how it works? 

Thirdly, we know almost nothing about how components should be assembled in the packages, for example in what order or dosage, or whether some components are more beneficial for some patients and less beneficial for others. Consequently, we lack the possibility to tailor packages to maximise overall effectiveness or devise personalized interventions.

To move forward, the field of psychotherapy needs a fundamental shift in perspective from treatment brands and packages toward treatment components. Efficacy, mechanisms of action or personalisation would all start to be examined in relation to treatment ingredients, not whole packages. In the European Research Council (ERC)-funded research project DECOMPOSE, Disentangling psychological interventions for mental disorders into a taxonomy of active ingredients, we will employ a systematic, comprehensive and reproducible approach for decoding, classifying and evaluating the active ingredients of psychological interventions. 

The goal is to dismantle interventions into components, integrate these into a taxonomy, and radically reevaluate treatment efficacy and personalisation using components as units of analysis. We will draw on both established (distillation of components, taxonomies) and emerging methodologies (component network meta-analysis). The starting point is represented by recent network meta-analyses – a type of meta-analysis that allows estimating comparative effects even for interventions that were never directly compared in a trial. From these, we will assemble a large library of psychological interventions for severe mental disorders (psychotic, bipolar, substance use, eating and borderline personality).

For each intervention, we will retrieve protocols and extract components iteratively, via multiple rounds of independent coding. We will integrate components in a cross-disorder, comprehensive taxonomy, validated in Delphi surveys and a consensus meeting. We will reevaluate psychological interventions for severe disorders through component network meta-analysis, to identify the most beneficial ingredients and combinations, for a large range of outcomes ranging from symptoms, functioning or staying in treatment.

We will reassess treatment personalisation through a component-based lens using already assembled individual participant data for psychosis. Finally, we will develop an open clinical decision support system, where users can 'assemble' and 'dismantle' interventions, visualising efficacy gain or loss. The clinical decision support system is envisioned as a tool for planning treatment delivery in practice or in research and a 'living' infrastructure that can be continuously adapted, for example by adding new disorders. 

Of course, the feasibility and usefulness of such a tool would need further testing, and this is one of the ways in which the European Congress of Psychology theme of 'uniting communities' comes in. Working on and with DECOMPOSE could help overcome the sometimes stark divisions between psychotherapy approaches, and foster more cohesion within the community of researchers and clinicians.

Might we see a growing realisation that different approaches rely on overlapping elements, along with a renewed appreciation for those elements that remain distinctive? Could ingredients shown to be efficacious, regardless of their theoretical provenance, represent the building blocks of new interventions? Would training in psychotherapy be reconsidered through a component lens, with trainees becoming proficient in administering active ingredients, regardless of theoretical orientation?

I am hopeful that a taxonomy of treatment components would be a major step towards a common language. Have you already been speaking this language? Are you keen to hear more? I hope to see you at my European Congress of Psychology keynote in Brighton this July, and if you can't make that do reach out on [email protected]

Ioana A. Cristea is an Associate Professor of Clinical Psychology at the Department of General Psychology, Padova, Italy and a Research Affiliate at the Meta-Research Innovation Center at Stanford University, USA. She is a keynote speaker at the European Congress of Psychology.