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 numbe