Ch1: Mental Disorders As Discrete Clinical Conditions: Dimensional Versus Categorical Classification

Question 1

Where do diagnostic criteria come from?

Answer 1

• diagnostic and statistical manual of mental disorders, fifth edition (DSM - 5)
• published by the American Psychiatric Association
• used in the USA and some other countries worldwide

Question 2

What is Classification?

Answer 2

Classification refers to the assignment of people to defined groups on the basis of shared attributes or relationships, although it’s helpful in the medical field, it’s more difficult to apply to human behavior.
Categories facilitate conversations for scientists and clinicians

Question 3

Categorical Classification

Answer 3

• traditionally used form of classification in the medical field developed by Emil Kraepelin
• assumes that disorders have specific etiologies, pathologies and treatments
• assumes disorders are qualitatively distinct from normal functioning and from one another

Question 4

Limitations of Categorical Classification

Answer 4

• doesn’t account for comorbidity - the co-occurence of distinct disorders, apparently interacting with one another
• certain disorders do not have distinct boundaries
• symptoms may be better viewed along continuous dimensions of functioning

Question 5

Limitations of Categorical Classification: Comorbidity

Answer 5

Approximately 95% of individuals in a clinical setting who meet criteria for lifetime major depression or dysthymia also meet criteria for a current or past anxiety disorder; suggests the presence of a common, shared pathology

Question 6

Limitations of Categorical Classification: Boundaries

Answer 6

• no meaningful distinction can be made among many psychological disorders (eg. early-onset dysthymia and depressive personality disorder)
• difficult to distinguish between normal expression of a negative emotion and having a mental disorder
• duration cutoffs are seemingly arbitrary

Question 7

Limitations of Categorical Classification: Boundaries for Substance Abuse and Dependence

Answer 7

• diagnosis does still refer to a disease, but one that is developed through normal social learning history
• this diagnosis has been broadened in DSM 5, referred to as a behavioral addiction that includes pathological gambling
• the boundary between a behavioral addiction and substantial interest in an activity that a person finds highly pleasurable is difficult to demarcate
• distinction between harmful substance use and a substance use disorder is itself unclear and indistinct

Question 8

Limitations of Categorical Classification: Boundaries for personality disorders

Answer 8

• no clear or consistent boundary between the personality disorders and many other mental disorders, particularly certain mood, anxiety, impulse descontrol, and psychotic disorders
• excessive participation in shopping, sex or the internet were considered for DSM 5
• no clear boundaries between personality disorders and Normal personality

Question 9

Limitations of Categorical Classification: Boundaries for intellectual disability

Answer 9

• precedent for dimensional classification
• intellectual disability in DSM-5 continues to be diagnosed along a continuum of cognitive and social functioning
• intellectual disability may serve as an effective model for the classification of the rest of the diagnostic manual

Question 10

Dimensional Classification

Answer 10

• Symptoms reflect quantitative deviations from normal functioning along particular dimensions to create a profile of emotional functioning
• allows for a distinction between “very sad” and having a major depressive disorder

Question 11

DSM 5

Answer 11

• primary goal was to shift to a dimensional system
• however remains a categorical classification of separate disorders
• largely rejected by NIMH in favor of the research Domain Criteria (RDoC)

Question 12

FFM five-factor dimensional model

Answer 12

Consists of 5 broad domains of general personality functioning:
- neuroticism (or emotional instability)
- extraversion vs introversion
- openness vs closedness
- agreeableness vs antagonism
- conscientiousness vs undependability

Question 13

How does DSM-5 dimensional trait model differ from FFM?

Answer 13

It is confined to maladaptive personality functioning and it is unipolar in structure (does not recognize any maladaptive variants of extraversion that is opposite to detachment, or agreeableness that is opposite to antagonism)

Question 14

Research Doman Criteria RdoC

Answer 14

Consists of 5 broad areas of research:
- negative valence systems
- positive valence systems
- cognitive systems
- systems for social processes
- arousal/modulatory systems

Question 15

According to RdoC mental disorders are:

Answer 15

Biological disorders involving brain circuits that implicate specific domains of cognition, emotion or behavior

Question 16

Comorbidity

Answer 16

Co-occurrence of distinct disorders, apparently interacting with one another, each presumably with its own independent etiology, pathology and treatment implications

It is a norm, rather than exception

Question 17

Taxometrics

Answer 17

A series of related statistical techniques to detect whether a set of items is optimally understood as describing (assessing) a dimensional or a categorical construct

Question 18

Hierarchical Taxonomy of Psychopathology (HiTOP)

Answer 18

• An alternative approach to the DSM-5, which treats all disorders as spectra that vary from typical functioning to impaired functioning. The focus is on a few specific spectra/dimensions that then give rise to disorders.
• 2 broad domains of externalizing dysfunction and emotional that cut across the mood, anxiety, substance use, psychotic and personality traits (internalizing, though disorder, misconduct, antagonism, and detachment)