Co-occurrence
Comorbidity is a term used to describe the existence of one or more distinct disorders other than the primary disorder with each having its own pathology, etiology as well as treatment implications. Some authors like Israel, Lilienfeld and Waldman have proposed that the term comorbidity be abandoned and be substituted by the term co-occurrence (Samuel & Widiger, 2005).
They argue that diagnostic comorbidity is wide-ranging and therefore the term co-occurrence would provide more clearly descriptive diagnosis and at the same time it does not emphasize the existence of distinct clinical entities. Co-occurring diagnoses suggest the existence of common as well as shared pathologies which is more valid as compared to comorbidity which suggest distinct psychopathologies.
Disordered personalities versus normal personality
Researchers have been able to identify that the disordered personality and normal personality have a common underlying structure in terms of quality of functioning. The structures of disordered personality traits or dimensions resemble the structures of normative traits and dimensions in terms of genetic as well as phenotypic structure which make up personality.
These common underlying structures hold for higher-order traits of personality disorders since the dimensions of personality disorders are highly related to the Big Five Factors of normal personality which include neuroticism, conscientiousness, agreeableness as well as extraversion. These four five-factor model factors correspond quite well with the four domains of disordered personality functioning (Samuel &Widiger, 2005).
Not Otherwise Specified (NOS)
According to Samuel and Widiger (2005) the most commonly applied diagnosis in clinical settings is the NOS which falls under the wastebasket category. It is applied in a situation where a clinician has confirmed that a personality disorder exists in an individual; however, he or she has failed to meet the set diagnostic criteria.
The fact that the diagnosis is the most commonly used implies that the current diagnostic categories do not have clinical utility. The major reason as to why NOS is used commonly is inadequate diagnostic coverage. This implies that the existing DSM-IV diagnostic categories provide inaccurate results as well as misleading descriptions for each patient’s psychopathology and as such they fail to provide adequate diagnostic assessment.
According to (Samuel &Widiger, 2005) the DSM-IV categories have failed to provide accurate assessment and descriptions of a number of conditions for personality disorders such depression and therefore many patients go untreated. Samuel and Widiger (2005) state that most pharmacologic interventions are done by primary care physicians since DSM-IV categories have failed to provide proper diagnosis using the existing diagnostic criteria for personality disorders.
Mixed anxiety-depressive disorder
The anxiety disorder that has been used by the authors to illustrate the existing boundary dispute between the DSM-IV’s categorical models is the Mixed Anxiety-Depressive Disorder (MADD). People diagnosed with MADD have depressive as well as anxious symptoms that call for clinical intervention yet they can not be diagnosed with either of the two.
According to Samuel &Widiger (2005) it was developed as an acknowledgment that a significant number of people suffer clinically considerable mood as well as anxiety disorder symptomatology; however, these symptoms do not meet the attributes for either anxiety or mood diagnosis.
A proposed criterion for diagnosis of MADD was performed for DSM-IV in a field trial by the Mood Disorders Work Group (Samuel &Widiger, 2005). The research involved 7 sample population which included 5 primary care as well as 2 psychiatric outpatient facilities with both of them having more than 550 persons receiving treatment for either anxiety, mood or both disorders.
Samuel and Widiger (2005) reported that those patients who had sub-definitional threshold affective signs showed similar symptoms to patients who had several DSM-III-R anxiety as well as depressive disorders. According to Barlow et al. the results of the study indicated that patients with sub-definitional threshold symptoms do not exhibit any specific pattern for distinguishing between depressive and anxiety symptoms.
The Mood Disorders Work Group therefore concluded that patients with these personality disorders showed almost equally balanced symptoms which are commonly found in depressive as well as anxiety disorders. These disorders were therefore categorized under anxiety disorder not otherwise specific (NOS) as well as in depressive disorder not otherwise specific.
This meant that DSM-IV had to classify mixed anxiety-depressive disorder as one distinct disorder since they exhibit almost similar symptoms difficult to categorize. DSM-IV therefore categorized MADD under mood disorder or anxiety disorder since it had no basis for selecting one category.
In addition, a study on general personality trait that results from neuroticism also provided empirical basis for classifying MADD in DSM-IV (Barlow & Campbell). This meant that MADD could therefore be classified under three categories which include anxiety, personality as well as mood disorder.
Categorical and dimensional models of classification
When considering the usefulness of the categorical model of classification, the major reason as to why it has always been preferred is that they usually appear easier to use (Samuel &Widiger, 2005). One diagnostic label can reveal a significant amount of information useful for clinical treatment in a more vivid manner.
Clinical decisions on administration of medication, insurance coverage as well as hospitalization are always categorical. On the other hand, dimensional models of classification are often viewed as more complex as compared to other diagnostic categories since they generally generate more specific as well as precise information.
Potentially more useful model
A diagnosis model that can be used to solve the dispute between the categorical or dimensional models of classification is the Not Otherwise Specific which falls under the wastebasket category. It is used to provide accurate diagnostic assessment and describe the personality disorder after it has been confirmed that the individual has a mental disorder.
It can be used to provide accurate diagnosis to schizoaffective disorder. It can help develop a criterion for determining the unique distinctions that exist between mood disorders and schizophrenia as well as making differential diagnosis to determine the difference that exist in affective disorder and schizophrenia (Samuel &Widiger, 2005).
Failures of categorical models of classification
Lack of specific treatment strategy that result from the use of categorical models of classification reflects the weakness of the model. According to Samuel and Widiger (2005) people with similar categorical diagnosis may differ significantly on the predominant features of that particular disorder meaning that the intervention and treatment methods undertaken may not yield positive results on some individuals.
A dimensional model of classification can therefore be used to provide a more specific as well as individualized profile description of an individual’s psychopathology. This will help achieve more differentiated as well as specific treatment implications.
Reference List
Samuel, D. B., & Widiger, T. A. (2005). Diagnostic categories or dimensions? A question for the diagnostic and statistical manual of mental disorders, 5th ed. Journal of Abnormal Psychology, 114 (4): 494-504. Washington, DC: American Psychological Association.