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The P factor of general psychopathology: what is it?

The P factor of general psychopathology: what is it?

November 21, 2023

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

Then we will see where the hypothesis of the P factor in general psychology arises and what it proposes.

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The diagnosis in psychiatry: categorical model and dimensional model

As we know them 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 maximum representative is the American Psychiatric Association (APA, for its acronym in English).

Each year, the group of specialists assigned to the latter publishes a diagnostic and statistical manual (DSM, for its acronym in English), which categorizes and describes a series of manifestations known as "mental disorders."

The above is relatively recent (formally initiated in the early 1950s) and currently constitutes one of the criteria most used to understand and treat these manifestations . In addition, with the passage of time, their criteria has 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 consisted of.

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The categorical model

As we have seen, it was in the second half of the 20th century that 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 it became one of the most 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, every mental disorder would have its own criteria, symptoms, course, prevalence and a set of particular characteristics . Due to this categorization exercise, this is known as a "categorical model".

However, with the passage of time, it was increasingly difficult to sustain such a model with the necessary rigor: it became clear that what was defined as a specific mental disorder had much to do with one or more disorders. This relationship between one and the other was described under the medical term of "comorbidity" , which means just "presence of one or more diseases or disorders in addition to the primary".

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

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

These figures left doubts about the specificity of the classifications, in addition to having evident clinical consequences: many people, instead of having only one diagnosis, which allowed them to understand and modify their discomfort, obtained two or more; what in could represent more harm than benefits.

In addition, the high rates of comorbidity meant that the decision about whether one is a disorder or another (and the following psychological and / or pharmacological intervention), far from falling into empirical and objective evidence, fell on the personal criteria of the professional ; issue that was increasingly criticized by the community of specialists and 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 distinguishing and particular characteristics, It seemed to be a broad 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 to make diagnoses by means of broad criteria that, in turn, allowed to understand the manifestations in a multifactorial way .

This poses an important question to psychopathology specialists: yes, contrary to what we thought, mental disorders are not specific but have a high index of comorbidity; probably this means that there is a broad phenotypic structure in the genesis of them.

From there, different investigations were given to 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 performed a multifactorial analysis to evaluate a new hypothesis about the underlying structure in 10 common mental disorders among young adults (18 to 21 years of 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: internalization, externalization and thought disorders .

The first dimension is related to diagnoses of mood (such as depression or anxiety), the second is linked to diagnoses of social behavior (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 constraint that contributes significantly in its structuring. This element is called "Factor P" (by analogy to the concept of "Gactor g" in intelligence) and is caused by a genetic activity, but also by family history of depression, anxiety, psychosis, antisocial disorders or substance abuse. In addition, the same factor may be related to potential risk factors such as the history of abuse or abuse during childhood.

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

Thus, it is a common element in the origin, development and absence of the 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.

Psychological Disorders: Crash Course Psychology #28 (November 2023).

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