psychpathology - conceptual model

what are the purposes of a classification system?

description, prediction, theory, communication

description purpose

highlight critical features of a diagnosis

prediction purpose

may tell you something about course, treatment response, etiology

theory purpose

provides a set of postulates about relationships of different elements to one another

communication purpose

to facilitate understanding between clinicians

Robins & Guze’s five criteria for valid classification of disorders

clinical description, course, treatment response, family history, laboratory studies

clinical description criteria

the disorder has to be characterized by a common set of symptoms that cluster together

course criteria

people with the disorder should follow a common trajectory, and have a similar onset

treatment response criteria

if a disorder is valid, most people will respond similarly to similar treatments

family history criteria

does the disorder run in families? if so, speaks to validity of a diagnosis

laboratory studies criteria

look for biological and psychophysiological associations

limitations of a classification system

loss of uniqueness and difficulty of boundary cases

loss of uniqueness limitation

diagnosis implies that common features are more important than the ways in which individuals vary

difficulty of boundary cases

what do you do about the people who are on the boundary? diagnose both or decided which group they’re more similar to

categorical systems

presence or absence of a disorder

dimensional system

rank on a continuous quantitative dimension, degree to which a symptom is present

advantage of dimensional system

may better capture an individual’s functioning

advantage of categorical system

advantages for research and understanding

DSM-I

1952

DSM-II

1968, few categories, no requirements for number of symptoms, psychoanalysis as the dominant paradigm

DSM-III

1980, demand for a more biological, empirical approach

DSM-III additions

inclusion criteria, duration criteria, exclusion criteria, and multi-axial classification

inclusion criteria

what symptoms do you need to have, and how many?

duration criteria

how long do you need to exhibit these symptoms?

exclusion criteria

what symptoms rule out a diagnosis?

axis I disorders

major clinical disorders

axis II disorders

personality disorders

axis III

medical conditions that might contribute or be relevant to treatment

axis IV

psychosocial stressors, something with which to record environmental contexts

axis V

GAF, a simple rating of function/summary score for severity

assumptions introduced in DSM-III

symptoms are the most useful basis for assessment, locus of pathology is in the individual

DSM-IV

1994, introduced clinically significant distress or impairment in social, occupational, or other important areas of functioning

DSM-IV-TR

2000, didn’t introduce new diagnoses or specific criteria, provided more information on each diagnosis, provided a broad definition of mental illness

DSM-V

2013, removed multi-axial system, introduced dimensional assessment criteria for some diagnoses, re-classified some disorders, removed others

why does comorbidity exist?

perhaps multiformity, causal explanation, or shared etiological risk factors

prevalence

percentage of people in a population with a disorder at a particular point in time

incidence

percentage of people who develop a disorder for the first time during a specific time period

risk factor

for epidemiologists, a correlate (most often demographic variables) associated with different disorders

1-year prevalence of MDD

6.7%

onset of MDD

14-15, 30s

1-year prevalence of PDD

1.5%

onset of PDD

30s

1-year prevalence of bipolar

2.6%

onset of bipolar

around 25

1-year prevalence of panic disorder

2.7%

onset of panic disorder

around 24

1-year prevalence of OCD

1%

onset of OCD

child/adolescent

1-year prevalence of social anxiety disorder

6.8%

onset of social anxiety disorder

around 13

1-year prevalence of GAD

3.1%

onset of GAD

around 31

1-year prevalence of PTSD

3.5%

onset of PTSD

any age

lifetime prevalence of mood disorders

21%

lifetime prevalence of anxiety disorders

27%

lifetime prevalence of substance use disorders

15%

lifetime prevalence of any disorder

46%