Dimensional models of personality disorders

In personality pathology, dimensional models of personality disorders (also known as the dimensional approach to personality disorders, dimensional classification, and dimensional assessments) conceptualize personality disorders as quantitatively rather than qualitatively different from normal personality. They consist of extreme, maladaptive levels of certain personality characteristics (these characteristics are commonly described as facets within broader personality factors or traits). Within the context of personality psychology, a 'dimension' refers to a continuum on which an individual can have various levels of a characteristic, in contrast to the dichotomous categorical approach in which an individual does or does not possess a characteristic. According to dimensional models personality disorders are classified according to which characteristics are expressed at which levels. This stands in contrast to the traditional categorical models of classification, which are based on the boolean presence or absence of symptoms and do not take into account levels of expression of a characteristic or the presence of any underlying dimension.Ein Triebststem muß aus Triebgegensatzpaaren konstituiert werden, die einerseits in jedem Individuum vorhanden sind, andererseits mit den pathopsychologischen, d.h. Psychiatrischen Erbkreisen genau übereinstimmen. (...) Die psychiatrische Vererbungslehre hat bisher drei selbständige Erb Kreise der Geisteskrankheiten festgestellt. In personality pathology, dimensional models of personality disorders (also known as the dimensional approach to personality disorders, dimensional classification, and dimensional assessments) conceptualize personality disorders as quantitatively rather than qualitatively different from normal personality. They consist of extreme, maladaptive levels of certain personality characteristics (these characteristics are commonly described as facets within broader personality factors or traits). Within the context of personality psychology, a 'dimension' refers to a continuum on which an individual can have various levels of a characteristic, in contrast to the dichotomous categorical approach in which an individual does or does not possess a characteristic. According to dimensional models personality disorders are classified according to which characteristics are expressed at which levels. This stands in contrast to the traditional categorical models of classification, which are based on the boolean presence or absence of symptoms and do not take into account levels of expression of a characteristic or the presence of any underlying dimension. The way in which these diagnostic dimensions should be constructed has been under debate, particularly in the run up to the publication of the DSM-5. A number of dimensional models have been produced, differing in the way in which they are constructed and the way in which they are intended to be interpreted. There are four broad types of dimensional representation, although others also exist: The dimensional approach is included in Section III ('Emerging Measures and Models') of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), where it is described as an 'Alternative DSM-5 Model for Personality Disorders.':p.761–781 The decision to retain the old DSM-IV categorical model of personality disorders in DSM-5 was controversial, and efforts continue to persuade the American Psychiatric Association to replace it with the dimensional model in DSM 5.1. Dimensional modals are intended to reflect what constitutes personality disorder symptomology according to a spectrum, rather than in a dichotomous way. As a result of this they have been used in three key ways; firstly to try to generate more accurate clinical diagnoses, secondly to develop more efficacious treatments and thirdly to determine the underlying etiology of disorders. The 'checklist' of symptoms that is currently used is often criticized for a lack of empirical support and its inability to recognize personality-related issues that do not fit within the current personality disorder constructs or DSM criteria. It has also been criticized for leading to diagnoses that are not stable over time, have poor cross-rater agreement and high comorbidity suggesting that they do not reflect distinct disorders. In contrast the dimensional approach has been shown to predict and reflect current diagnostic criteria, but also add to them. It has been argued to be especially useful in explaining comorbidity which is often high for patients diagnosed with a personality disorders. Following from these claims, the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) incorporates a combined categorical-dimensional approach to diagnosing personality disorders based on the degree to which a person shows elevated levels of particular personality characteristics. However one of the issues in using a dimensional approach to diagnosis has been determining appropriate cut off points so as to know who belongs to the category of people requiring treatment, this is partly why both categorical and dimensional diagnoses are included. Since the categorical model is widely used in clinical practice and has a significant body of research supporting it, its common usage is compelling to laypeople when they are judging the credibility of professional opinion. Therefore, the dimensional approach is often further criticized for being difficult to interpret and less accessible. It is however widely used in some professional settings as the established approach, for example by forensic psychologists. Another suggested usage of the dimensional approach is that it can aid clinicians in developing treatment plans and assessing other mechanisms contributing to patient’s difficulty in functioning within the social, personal, or occupational domains. The approach can improve treatment in two ways. Firstly it can enable development of more personalized care plans for individuals based on their adaptive and maladaptive characteristics. Secondly, it means that relevant symptomology which is not considered maladaptive can be considered when developing and evaluating general therapeutic and medical treatment. Attempts at presenting an etiological description of personality disorders have been avoided due to the influence of the DSM and its principles in psychiatric research (See history section). However some techniques are looking at potential interrelated causalities between symptoms of personality disorders and broader influences including aspects of normal personality (See integrated approaches section). The adoption of a categorical approach to personality disorders can be understood in part due to ethical principles within psychiatry. The ‘do no harm principle’ led to Kraepelinian assumptions about mental illness and an emphasis on empirically grounded taxonomic systems that were not biased by unsubstantiated theories about etiology. A taxonomic checklist based on empirical observations rather than bias prone theoretical assumptions developed. It was both categorical and hierarchical, with the diagnosis of a disorder being dependent of the presence of a threshold number categories (usually five) out of a total number (seven to nine) Disorders were organized into three clusters, existing purely to make the disorders easier to remember by associating them with others that have similar symptoms, not based on any theory about their relatedness.