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Classification & Research

Classification & Research. The study of mental disorder involves:. Definition: What do we mean by mental disorder? Classification : How do we distinguish between different mental disorders? Explanation: How do we understand mental disorder? Treatment: How do we treat mental disorder?.

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Classification & Research

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  1. Classification & Research

  2. The study of mental disorder involves: • Definition: What do we mean by mental disorder? • Classification: How do we distinguish between different mental disorders? • Explanation: How do we understand mental disorder? • Treatment: How do we treat mental disorder?

  3. Example • Animal • Dog • Cat

  4. LINNAEAN  CLASSIFICATION • Kingdom:  Animalia  Phylum:  Chordata   Subphylum:  Vertebrata      Class:  Mammalia         Subclass:  Theria            Infraclass:  Eutheria              Order:  Primates                Suborder:  Anthropoidea                 Superfamily:  Hominoidea                   Family:  Hominidae                     Genus:  Homo                       Species:  sapiens

  5. Why is it important to classify mental disorders? • Scientific communication and research • Treatment

  6. Classification and Diagnosis • Classification systems exists before and independently any individual • Individual people are said to be diagnosed or put into the classification system based on a psychological assessment

  7. Evaluating classification systems and assessment tools? • Reliability: Gives the same answer with repeated measurement or assessment • Test re-test • Inter-rater or inter-judge

  8. Evaluating classification systems and assessment tools? • Validity: Measures or assesses what it claims to measure • Descriptive, construct • Predictive

  9. Three broad ways to classify mental disorder • Categorical Approach • Dimensional Approach • Prototypal Approach

  10. Categorical Approach • Characteristic of medical diagnostic systems. • Assumptions: • Behavior can be divided into categories of “healthy” and “disordered”. • There are discreet, non-overlapping types of “disorder” • Members of each diagnostic group share the same features.

  11. Dimensional Approach • Characteristic of personality assessment approaches. • Assumptions: • Behavior comes from different strengths/intensities of underlying attributes (e.g., aggressiveness, introversion). • People differ along a continuum of normality to abnormality on these dimensions.

  12. Prototypal Approach • There are imperfect but recognizable combinations of characteristics that cluster together. • These imperfect clusters define abnormal behavior. • Assumptions: • No people share all of the features of the prototype. • All people share most of the features of the prototype.

  13. Defines what is abnormal • Classifies mental disorders into different sub-types and provides defining criteria • Medical tradition: • Categorical in intention • Prototypal in practice

  14. DSM-IV • Created with assumptions of the categorical approach • BUT… • Central features of Dx categories are sometimes unclear. • Many shared features between Dx categories. • Large amount of co-morbidity.

  15. DSM-IV DSM-IV classification is prototypal because... • Fuzzy boundaries between categories. • Overlap of categories themselves.

  16. DSM-IV: A short history • DSM = Diagnostic and Statistical Manual (of mental disorders) • Currently in 4th edition (May, 1994).

  17. DSM I and II: • Included a lot of jargon. • Narrative categories. • Categories not well defined. • Generally not reliable. DSM III (1980): • Radically new approach...

  18. DSM-III • Precise definitions of Dx categories. • Necessary requirements to meet Dx category. • First attempts to establish reliability and validity for Dx categories.

  19. DSM-IV • Latest edition (1994) • Five Axis structure: Axis I - Clinical Syndromes Axis II - Personality Disorders Axis III - Related Medical Conditions Axis IV - Psychosocial and Environmental Problems Axis V - Global Assessment of Functioning.

  20. DSM-IV criticisms: 1. Long-term outcome of disorders is largely unknown. 2. Still little known about etiology. 3. High co-morbidity among Dx. 4. Reliability emphasized at expense of validity (?)

  21. DSM-IV criticisms cont. 5. Perpetuation of flawed Dx categories (from past DSMs). 6. Too many dimensions require rating.

  22. Problems Labeling Pseudo-explanations Lack of reliability Classification

  23. Classification Advantages: • Communication shorthand • Treatment planning • Etiology • Aid to scientific investigation

  24. Further Exploration: Classification • Millon, T. (1991). Classification in Psychopathology: Rationale, Alternatives, and Standards. Journal of Abnormal Psychology, 100(3), 245-261. • Krueger, R., Piasecki, T., M. (2002). Toward a dimensional and psychometrically-informed approach to conceptualizing psychopathology. Behaviour Research and Therapy, 40, 485-499.

  25. Research Methods and Critical Thinking

  26. Observation • Like all sciences the “bedrock” is observation/description • Observation as theory free or theory laden • Description determines what we can then later say about a phenomenon • Reliability and Validity

  27. Hypotheses & Predictions • Hypothesis: A claim about observations/descriptions that could be true or false that attempts to explain or understand the world • Tested by making predictions • Prediction: also important from a clinical point of view, not just to test hypotheses • Can predict without understanding

  28. Understanding • Understanding: Usually means “what causes X” could also mean “what is it like, or what does it mean to a person to have X”

  29. Causality: • Requirements for inferring causality: 1) Covariation - purported cause and observed effect vary together. 2) Temporal Precedence - purported cause occurs before the observed effect. 3) Exclusivity - the purported cause is the only thing that can explain the observed effect.

  30. Correlation / Covariation vs. Causation • Hypothesis: Stress causes depression • Need to show that depressed people (Criterion Group) had higher stress levels, before becoming depressed, than other people who do not become depressed (Control Group).

  31. Control / Intervention • Without understanding it is hard to control or intervene

  32. Research Designs • Intensive observation of a single case • Observation of groups

  33. Internal and External Validity • Internal validity • The study can make accurate conclusions because there are no confounds or alternative explanations • External validity • The results can be generalized to people outside the study

  34. Sampling and Generalization • Population: Everyone who has the mental disorder that you want to make claims about • Sample: A smaller group of people from the lager population of interest • Random Sampling: Everyone in the population has an equal chance of being in the sample

  35. Sampling and Generalization • If the sample is not random, or not a good mix of all the people that have the mental disorder then the conclusions may not have external validity or may not generalize

  36. Methods of Control • Manipulating or systematically changing one variable while controlling or holding constant other variables • Allows us to conclude that any observed effects of changing a variable are really due to it and not other variable

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