1. Systems of Classification
Year 12 Psychology Unit 4
Area of Study 2 (chapter 11, page 558)

2. Systems of Classification of Mental Conditions & Disorders
Classification: organising items into groups based on their shared characteristics.
Two main classifications of mental illness:
Categorical approaches: organises mental disorders into categories, each with specific symptoms and characteristics.
Dimensional approaches: classifies symptoms quantitatively in terms of their severity, or ‘how much’ (i.e. ranking).
Often both are used to provide an overall assessment.

3. Categorical Approach
Diagnosis involves a comparison of patients symptoms to the listed symptoms within each category:
Check your patient’s list against the lists in the DSM-IV to find a fit – then make diagnosis.
Assumes that mental disorders can be diagnosed from specific symptoms reported by the patient or observed by the professional.
Thoughts feelings and behaviours can be categorised – certain categorisation relates to specific disorders.
There are distinct sub categories within each disorder.
All or nothing – they either have it or they don’t. You can’t ‘kind of’ have schizophrenia.
The system must be valid and reliable.

5. Diagnostic & Statistical manual of Mental Disorders
The system most widely used by mental health professionals throughout the world to identify and classify mental illnesses for the purposes of diagnosis.
More commonly called the DSM.
An important feature of the DSM-5 is that it does not suggest causes of specific disorders unless a cause can be definitely established:
It simply names the disorders and describes them in specific terms.

6. DSM-5
365 disorders comprehensively described (one for every day of the year!).
Grouped into 17 categories.
Diagnosis matches patient symptoms to the disorder symptoms.
Symptoms are considered characteristics of disorders so looking at these enables diagnosis:
Inclusion criteria: symptoms that must be present for diagnosis;
Exclusion criteria: symptoms that must not be present;
Polythetic criteria: only some symptoms need to be present for diagnosis – e.g. “3 of the following 8.”
Provides info on the typical course of the disorder.

7. DSM-5 (axes)
Axis I: clinical disorders. Symptoms that cause distress or significantly impair social or occupational functioning (such as anxiety disorders, depression). SEE BOX 11.5 ON PAGE 562.
Axis II: personality disorders and mental retardation. Chronic and enduring problems that generally persist throughout life and impair interpersonal or occupational functioning (such as multiple personality disorder).
Axis III: general medical condition. Physical disorders that may be relevant to understanding or treating a psychological disorder.
Axis IV: psychosocial and environmental problems (such as interpersonal stressors and negative life events). Factors that may affect the diagnosis, treatment and prognosis (prediction of the course of a disease) of psychological disorders.
Axis V: global assessment of functioning. The individual's overall level of functioning in social, occupational and leisure.

9. International Classification of Diseases & Related Health Problems
Commonly known as ICD-10.
Diagnosis and classification of mental disorders based on recognised symptoms.
Includes detailed description of each disorder listed.
Identifies symptoms that indicate the presence of a disorder.
Original text covered all medical practice with mental disorders covered in Chapter V:
Chapter V now printed as a separate book.
Less detailed than the DSM –IV.

10. Strengths of Categorical Approaches
Activity: 11.14
Strengths of Categorical Approaches
Allows clear-cut diagnosis of mental disorders(this is the main purpose of the categorical approach).
Enhances communication between professionals by providing a common language:
Diagnostic labels can convey a large amount of information quickly and conveniently.
Very comprehensive list of disorders, symptoms and additional disorder information.
User-friendly system:
This fits with the ‘yes/no’ approach used by most healthcare professionals.

11. Limitations of Categorical Approaches
Historically low inter-rater reliability (different conclusions reached by different professionals):
Much better now with DSM-IV-TR and ICD-10: up to 70% agreement between mental health professionals
BUT still as much as 30% disagreement in classification of people with mental disorders and much lower inter-rater reliability for personality disorders.
Lots of overlap between symptoms can make diagnosis difficult.
Substantial loss of valuable clinical information: individuality of the patient becomes overlooked when they are simply categorised.
Categorisation and ‘labels’ can result in stigma.

12. Dimensional Approach
Determines how much of a characteristic is normal; numerical values are assigned to each characteristic score:
Measure all characteristics and the combination of scales that are statistically extreme might point to the type of illness being suffered.
Dimension: cluster of related psychological/behavioural characteristics that occur together.
Quantifies symptoms and other characteristics with numerical values:
These values are compared with the statistically ‘normal’ expected values for each characteristic;

13. Minnesota Multiphasic Personality Inventory (MMPI)

14. Scales on the MMPI Hs Hypochondriasis Concern with bodily symptoms
D Depression Depressive Symptoms
Hy Hysteria Awareness of problems and vulnerabilities
Pd Psychopathic Deviate Conflict, struggle, anger, respect for society's rules
MF Masculinity/Femininity Stereotypical masculine or feminine interests/behaviors
Pa Paranoia Level of trust, suspiciousness, sensitivity
Pt Psychasthenia Worry, Anxiety, tension, doubts, obsessiveness
Sc Schizophrenia Odd thinking and social alienation
Ma Hypomania Level of excitability
Si Social Introversion People orientation

15. MMPI – the t scores
The t-score represents how statistically different each scale result is from the mean/average t- score (50):
Is the difference big enough to be significant?
Statistical normality is the key here!
Lower scores equate to lower impairment;
Higher scores equate to higher impairment.
SEE FIGURES ON PAGES 574 & 575

16. Strengths of Dimensional Approaches
Take into account a wider range of factors than categorical approaches.
More detailed information on each symptom (quantifying):
Not just a label, an assessment of the degree or extent of the illness.
Reduced stigma as labelling not used:
Instead a profile is created;
Patients are viewed as having extreme variants of common traits, rather than being labelled as completely ‘different’.

17. Limitations of Dimensional Approaches
Activity: 11.16
& 11.17
Limitations of Dimensional Approaches
There is no standardised inventory to compare individual scores to, thus diagnosis is difficult.
Mental health professionals need to create the questions and scales themselves (may have to rate a client on up to different 40 dimensions).
This makes using dimensional approaches a very time-consuming and difficult process.
Disagreement among professions and researchers on the number of dimensions that suitably represent the wide range of mental disorder symptoms people can experience:
If there are too many dimensions, assessment could become overcomplicated.