Transdiagnostic Therapy: A Move Away From the Labels of Diagnosis

Transdiagnostic therapy breaks away from the medical model and exposes an uncomfortable truth in psychology. It suggests that we're misdiagnosing.

Written and verified by the psychologist Loreto Martín Moya.

Last update: 10 April, 2023

A diagnosis is usually reassuring because it removes uncertainty. It acts as a negative reinforcement to ward off anxiety. When you have a diagnosis, you have a prescribed, proven solution. You have a ‘cure’. Transdiagnostic therapy doesn’t take away the reassurance of a diagnosis. However, it’s been developed due to certain risks that a traditional diagnosis entails.

As a matter of fact, there’s a high price to pay for the reassurance of a diagnosis. For example, you might find that certain elements of your condition are excluded because they aren’t seen as forming a part of the diagnosis. Consequently, you’re given a hodgepodge of mutually comorbid diagnoses. In fact, there’s a certain stigma attached to a traditional diagnosis.

This tends to pose the question, is qualitative categorical diagnosis necessary to be able to propose a rigorous, effective, and empathic treatment ? Although it’s always been thought that this was the key to the entire therapeutic process, transdiagnostic therapists tend to disagree.

The dimensional approach of the medical tradition

From its beginnings, the development of psychology needed to prove itself as a science to other disciplines. To start with, psychology didn’t really even take itself seriously and operated within the confines of another science: medicine.

For this reason, a similar vocabulary was adopted (physical illness vs. mental illness), a similar manual (MSD vs. DSM ), and similar categorizations. In medicine, different ailments are structured with diagnoses defined by specific symptoms. It was thought that the validation of psychology would therefore have to go through the same process.

This is one of the reasons why the categorical approach was used in diagnosing different psychological disorders. Sandín, Chorot, and Valiente (2012) exposed its need to be ‘showy’ and ‘practical’.

Throughout the 20th century, the categorical model continued to be used satisfactorily. However, a few years ago, it became clear that it wasn’t working in the same way for psychological disorders as for physical disorders. We’re going to talk about the problems that the field of psychology has with the categorical tradition.

Exact definitions lead to endless manuals

The – increasingly preposterous – claim to categorize with watertight dimensions, as occurs in the medical model, means psychology has two major problems.

The first of them is related to the number of disorders that appear. Sandin et al. (2012) emphasized that in the first DSM, there were about 100 diagnoses. Nevertheless, in reality, there were around 300. In fact, each small differentiation in terms of form or frequency must be considered to be a different disorder. The list seems endless.

The second, perhaps even more worrying aspect, is the comorbidity of disorders. The NIH defines comorbidity as the term used to describe disorders that occur together in an individual. For example, there would be comorbidity between an anxiety disorder and an eating disorder if they were diagnosed at the same time, in the same person.

Various studies demonstrate that many diagnostic categories have extremely high rates of comorbidity with other disorders. For instance, according to Clark et al. (1995), OCD presents a 96 percent comorbidity with other disorders. This presents a problem.

What comorbidity reflects

Comorbidity puts the validity of disorders in check. Sandin et al. (2012) exposed the reasons why high comorbidity appears. The results aren’t flattering for the categorical system:

• The existence of different disorders when symptoms might only reflect a single disorder. For example, is the condition social phobia or avoidant personality disorder?
• Wrong diagnostic categories, poorly defined. Is it PTSD, dissociative, or anxiety disorder?
• Similar symptoms but presented as extremely different diagnoses. Is it a depressive disorder or generalized anxiety disorder?

Indeed, the approach of categorical diagnostic categories isn’t effective in the discipline of psychology. It’s like trying to define the result of a mathematical equation with colors. We’re talking about different things.

So, is the whole system on which psychology is based wrong? Not at all. Transdiagnostic therapy has the solution.

Transdiagnostic therapy: vulnerability vs. symptom

Various authors have exposed, in the development of transdiagnostic therapy, the factors that can cause the development of a psychological condition, along with a lesser and more generalized classification of those conditions.

Some speak of three types of vulnerabilities, whose dimensional movement gives rise to negative or positive affect disorders (Watson, 2009). Others speak of nuclear psychopathological mechanisms (Fairburn, 2003). Osma and Crespo (2018) unify all these theories and present a unified transdiagnostic protocol.

The triple vulnerability as mother and father of psychological disorders

These authors have taken the original idea of Barlow (2002) that Watson reaffirms and elaborated a system where everything is based on a triple vulnerability. Adjusting the values of these three factors gives rise to one or another psychological condition.

They’re not different symptoms, but they appear with more or less intensity and are related, therefore, in a different way. Therein lies the diagnostic inequality.

The factors that make up this triple vulnerability are:

1. Negative affect. This is sometimes known as neuroticism. It’s the tendency of a person to feel emotions in an intense and overwhelming way and to face the stressors of reality more or less calmly, with more or less desperation. As in the five-factor theory, we speak of a trait understood as being on a continuum. There are people with little negative affect, others with high levels, or some with levels that change throughout life.
2. Interpretation of the emotional experience. This is sometimes known as positive affect. Bruna and Gil (2017) define it as the categorization of emotional experiences as satisfactory, useful, and lawful. It doesn’t mean that the individual always has to feel badly-named ‘positive’ emotions, but rather that they interpret their entire emotional range.
3. Resulting behavior. What mechanisms does the individual put into practice to drive away those feelings that result from the emotion in question?

All of these combined factors could explain psychological conditions without the need for categories.

Transdiagnostic therapy: simultaneity without specificity

The main benefit of transdiagnostic therapy is related to comorbidity. In effect, comorbidities would disappear because they’d simply correspond to a greater negative affect, or perhaps to a specific interpretation of an emotion or experience.

Since transdiagnostic therapy focuses on core emotional processes (their origin and current functioning), it allows different problems to be addressed simultaneously. That’s because these problems emanate from the same processes (Osma and Crespo, 2018).

For example, if a patient’s eating problem and depressed mood are related to their levels of negative affect, they could be worked on directly, rather than within watertight categories.

Transdiagnostic therapy would also facilitate psychological practice. Therapists wouldn’t have to specialize in 300 types of treatments specific to each of the different diagnoses. As Osma and Crespo (2018) stated, they could learn interventions based on these factors. As such, they could provide evidence-based treatments that could be put into practice in more than one ‘diagnosis’.

Transdiagnostic therapy has begun to be put into practice but is it effective?

Although we should maintain caution in interpreting study results, the answers appear to be positive. In fact, transdiagnostic therapy seems effective for treating alcohol addiction and emotional disorders like BPD, and PTSD.

In addition, although this therapy presented a similar improvement to treatments based on categorical diagnoses, the transdiagnostic treatments presented a lower rate of abandonment.

Therefore, it appears that transdiagnostic therapy seems to be an alternative with clear potential. It was proposed by a group of brave researchers who dared to move away from the medical model.

In any case, people are continuing to go to therapy and the reputation of the discipline doesn’t appear to have been compromised.