The P factor of psychopathology is a proposition of psychologists Avshalom Caspi and Terrie Moffit, who suggest that psychiatric disorders have a common etiological basis and not specific or differentiated (as had traditionally been understood).
Then we will see where the P factor hypothesis comes from in general psychology and what he offers.
Diagnosis in psychiatry: categorical model and dimensional model
As we know them now, diagnoses in psychiatry have a recent history. This history was particularly marked by the presence of the American model of psychiatry, the highest representative is the American Psychiatric Association (APA, for the acronym in English).
Each year, the group of specialists attached to the latter publishes a diagnostic and statistical manual (DSM), which categorizes and describes a series of manifestations called “mental disorders”.
The above is relatively recent (officially started in the early 1950s) and is currently constituted one of the most widely used criteria to understand and treat these manifestations. In addition, over time, its criteria have been modified and updated according to the needs produced in the context itself.
One of the most important and recent changes concerns the need to expand diagnostic criteria, mainly due to growing doubts about the specificity of each disorder. In the following paragraphs, we will expand on what this change consists of in more detail.
The categorical model
As we have seen, it was in the second half of the twentieth century that the first Diagnostic and Statistical Manual of Mental Disorders of the American Psychiatric Association was published. What was originally consolidated as a compilation of psychopathology research, soon to be has become one of the most used diagnostic and clinical guides in the world.
At least until the first four versions of this manual, the tendency was to define clinical entities in specific and differentiated ways. In other words, just like physical illnesses, each mental disorder would have its own criteria, symptoms, course, prevalence and a set of particular characteristics. Due to the above-mentioned categorization exercise, it is referred to as a “categorical model”.
However, over time it became more and more difficult to maintain this model with the necessary rigor: it became evident that what was defined as a specific mental disorder had a lot to do with one or more disorders. This relationship between the two has been described under the medical term of “comorbidity”., Which means precisely “presence of one or more diseases or disorders in addition to the primary”.
Not only that, but the comorbidity was found to be sequential, meaning that over time many diagnoses ended up triggering others. And this was repeated very often in people attending a psychiatric consultation.
In addition to the above, some studies have shown that there were diagnoses with notable comorbidity and greater than others. For example, personality disorders had excessively high rates (about 60% of people diagnosed with personality disorders have comorbidities with mood diagnoses).
These figures left doubts about the specificity of the classifications, in addition to which they had obvious clinical consequences: many people, instead of having a single diagnosis, which allowed them to understand and modify their discomfort, obtained two or more. more; which could mean more harm than good.
In addition, the high rates of comorbidity meant that the decision of whether it was one disorder or another (and subsequent psychological and / or pharmacological intervention) was far from empirical evidence and objectives, fell under the personal judgment of the professional; a problem increasingly criticized by the community of specialists and those concerned.
The dimensional model
The development of the categorical model indicated that it was increasingly difficult to maintain a differentiated way of defining and treating diagnoses in psychiatry. Far from being an entity with distinct and particular characteristics, it seemed to be a wide range of manifestations that could hardly be separated.
Therefore, the American Psychiatric Association itself, in its fifth version of the Diagnostic and Statistical Manual, advocates the need to create a dimensional model. This would make it possible to make diagnoses using broad criteria which, in turn, make it possible to understand the manifestations in a multifactorial way.
The above raises an important question for psychopathologists: whether, contrary to popular belief, mental disorders are not specific but have a high rate of comorbidity; this probably means that there is a broad phenotypic structure in their genesis.
From there, various researches were given the task of questioning the categorical model as well as of studying and expanding the dimensionality of the diagnosis. One of the most representative in the field of psychopathology is the proposition of the factor P.
The P factor in psychopathology: a common structure in psychiatric diagnoses?
Avshalom Caspi and Terrie Moffit with their collaborators, published a study in 2014 in which they conducted a multifactorial analysis to assess a new hypothesis on the underlying structure of 10 common mental disorders in young adults (18 to 21 years old).
Using data from a previous multidisciplinary health study, the authors examined the structure of psychopathology considering dimensionality, persistence, coexistence and sequential comorbidity mental disorders over 20 years.
In their research, they conclude that mental disorders can be summarized from three general dimensions: internalization, externalization and disturbances of thought.
The first dimension is linked to mood diagnoses (such as depression or anxiety), the second is linked to social behavior diagnoses (such as borderline or antisocial personality) and drug addiction; and the third concerns the manifestations of psychosis.
The above dimensions would be supported by an element or a general condition that contributes significantly to its structuring. This element is called “Factor P” (by analogy with the concept of “Gactor g” in intelligence) and it is the result of genetic activity, but also of family history depression, anxiety, psychosis, antisocial disorders or substance abuse. Additionally, the same factor may be linked to potential risk factors such as a history of childhood abuse or misuse.
To put it another way, the authors consider that the P factor, as a common pattern in different psychiatric diagnoses, is linked to higher levels of deterioration in life, a higher history of mental disorders in the family, a higher index of negative stories during development of life. , and predominantly compromised early brain function.
Thus, it is a common element in the origin, development and absence of disorders; which leads the authors to advocate a “transdiagnostic” approach in psychiatry.
- Caspi, A., Houts, R., Belsky, D., Goldman-Mellor, Harrington, H., Israel, S. … Moffitt, T. (2014). The p factor: a general psychopathological factor in the structure of psychiatric disorders? Clinical Psychology Sici, 2 (2): 1190-137.