The P factor of general psychopathology: what is it?

The P factor of psychopathology is a proposal by psychologists Avshalom Caspi and Terrie Moffit, who suggest that psychiatric disorders have a common etiological basis and not a specific or differentiated one (as traditionally had been understood).

Next We will see where the P factor hypothesis in general psychology comes from and what is he proposing.

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Diagnosis in psychiatry: categorical model and dimensional model

As we know it now, diagnoses in psychiatry have a recent history. This history has been especially marked by the presence of the North American model of psychiatry, whose highest representative is the American Psychiatric Association (APA).

Every year, the group of specialists attached to the latter publishes a Diagnostic and Statistical Manual (DSM, for its acronym in English), where a series of manifestations known as “disorders” are categorized and described. mental”.

This is relatively recent (formally started in the early 1950s) and currently constitutes

one of the most used criteria to understand and treat these manifestations. In addition, with the passage of time, its criteria have been modified and updated according to the needs produced within the context itself.

One of the most significant and recent changes has occurred under the need to expand the diagnostic criteria, mainly due to growing doubts about the specificity of each disorder. In the following paragraphs we will develop in more detail what this change has consisted of.

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The categorical model

As we have seen, it was in the second half of the 20th century when the first Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association was published. What was initially consolidated as a compilation of research on psychopathology, soon became one of the most widely used diagnostic and clinical guides around the world.

At least until the first four versions of this manual, the tendency had been to define clinical entities in a specific and differentiated way. That is, just like physical illnesses, each mental disorder would have its own criteria, symptoms, course, prevalence and a set of particular characteristics. Due to such a categorization exercise, this is known as a “categorical model”.

However, as time went by, it became more and more difficult to sustain this model with the necessary rigor: it made it evident that what was defined as a specific mental disorder was closely related to one or more disorders. This relationship between one and the other was described under the medical term of "comorbidity"., which means precisely "presence of one or more diseases or disorders in addition to the primary one."

Not only this, but the comorbidity turned out to be sequential, that is, over time, many diagnoses ended up triggering others. And this was repeated very frequently among the people who attended a psychiatric consultation.

In addition to the above, some studies showed that there were diagnoses with notable comorbidity and greater than others. For example, personality disorders had excessively high rates (about 60% of the people with diagnoses of personality disorders have comorbidity with diagnoses of the state of cheer up).

These figures left doubts about the specificity of the classifications, in addition to the fact that they had clinical consequences. obvious: many people, instead of having a single diagnosis, which would allow them to understand and modify their discomfort, obtained two or more; which could represent more harm than benefits.

In addition, the high rates of comorbidity meant that the decision as to whether it is a disorder or a another (and the following psychological and/or pharmacological intervention), far from relying on empirical evidence and objective, relied on the personal judgment of the professional; an issue that was increasingly criticized by the community of specialists and those affected.

the dimensional model

The development of the categorical model indicated that it was increasingly difficult to sustain a differentiated way of defining and treating diagnoses in psychiatry. Far from being an entity with distinguishable and particular characteristics, seemed to be a wide spectrum of manifestations that could hardly be separated.

Consequently, the American Psychiatric Association itself, in its fifth version of the diagnostic and statistical manual, defends the need to create a dimensional model. This would allow diagnoses to be made using broad criteria that, in turn, allowed to understand the manifestations in a multifactorial way.

This raises an important question for specialists in psychopathology: if, contrary to what As we thought, mental disorders are not specific but have a high index comorbidity; This probably means that there is a broad phenotypic structure in their genesis.

From there, different investigations were given the task of questioning the categorical model as well as investigating and expanding the dimensionality of the diagnosis. One of the most representative in the field of psychopathology is the proposal of the P factor.

The P factor in psychopathology: a common structure in psychiatric diagnoses?

Avshalom Caspi and Terrie Moffit together with their collaborators, published a study in 2014 where they carried out a multifactorial analysis to To evaluate a new hypothesis about the underlying structure in 10 common mental disorders among young adults (18-21 years of age). age).

Using data from a previous multidisciplinary health study, the authors examined the structure of psychopathology considering dimensionality, persistence, coexistence and sequential comorbidity of mental disorders over 20 years.

In their research they conclude that mental disorders can be summarized from three general dimensions: internalizing, externalizing and thought disorders.

The first dimension is related to mood diagnoses (such as depression or anxiety), the second it is linked to diagnoses of social behavior (such as borderline or antisocial personality) and substance abuse; and the third is related to the manifestations of psychosis.

The previous dimensions would be supported by a general element or condition that contributes significantly to its structuring. Said element is called "Factor P" (by analogy to the concept of "Gactor g" in intelligence) and It is caused by genetic activity, but also by family history depression, anxiety, psychosis, antisocial disorders or substance abuse. In addition, the same factor may be related to potential risk elements such as a history of mistreatment or abuse during childhood.

To put it another way, the authors consider that the P factor, as a common structuring agent in different psychiatric diagnoses, is related with higher levels of life impairment, higher history of mental disorders in the family, higher rate of negative histories during life development, and a mostly compromised early brain function.

Thus, it is a common element in the origin, development and absence of disorders; which leads the authors to defend a “transdiagnostic” approach in psychiatry.

Bibliographic references:

• Caspi, A., Houts, R., Belsky, D., Goldman-Mellor, Harrington, H., Israel, S. … Moffitt, T. (2014). The p Factor: One General Psychopathology Factor in the Structure of Psychiatric Disorders? Clinical Psychology Sici, 2(2): 1190-137.