Psychiatric Classification: Diagnoses & Systems

• Psychiatric classification is a challenging issue with several problems to address.
• There is an introduction to new classification approaches.
• The goal is to understand the difficulties inherent in psychiatric classification.

Functions of Psychiatric Diagnoses

• Diagnoses help specify treatment approaches.
• They aid in predicting clinical outcomes.
• Diagnoses assist in predicting how patients will respond to treatment.
• They facilitate communication among clinicians.
• Diagnoses determine access to services.
• Diagnoses support public health surveillance efforts.
• They are used in selecting participants for research studies.
• Psychiatry utilizes a categorical diagnostic system for over a century, originating from Kraepelin's work.

Two Systems of Classification

• The American Psychiatric Association formed a task force in 1948, leading to the Diagnostic and Statistical Manual of Mental Disorders (DSM) in 1952.
• The DSM is currently in its 5th edition and was amended in 2022 to DSM-5-TR.
• The World Health Organization (WHO) took over the International List of Causes of Death in 1948, initially compiled in 1853.
• WHO added nonfatal diseases, including psychiatric disorders, when creating ICD-6 in 1951.
• The ICD is currently in its 11th edition (2018).
• Both DSM and ICD are categorical systems, dividing individuals into distinct categories.

The Problem of Comorbidity

• Comorbidity refers to any distinct additional clinical entity occurring during the course of treatment of a patient with an index disease.
• A useful paper on this subject is "The Conundrum of Psychiatric Comorbidity" by James Tew and Harold Alan Pincus, (2007).
• Comorbidity connects to Emil Kraepelin’s ideas.
• The network approach illustrates comorbidity, showing connections for individuals like Alice and Bob, involving Major Depressive Episode (MDE) and General Anxiety Disorder (GAD).

Revisions of DSM

• The DSM has undergone seven revisions, generating revenue for the American Psychiatric Association.
• DSM revisions include DSM-III (1980), DSM-IIIR (1987), DSM-IV (1994), DSM-5 (2013), and DSM-5-TR (2022).

DSM II – IV; Multi-axial System

• Multi-axial system was a way of coping with comorbidity
• Axis I included clinical disorders and conditions causing distress or impairment.
• Axis II covered personality disorders and intellectual disabilities.
• Axis III included general medical conditions that may contribute to psychiatric symptoms.
• Axis IV addressed psychosocial and environmental problems affecting clinical presentation.
• Axis V provided a global assessment of functioning (GAF).

DSM and Comobidity

• 1952 DSM a list of disorders and definitions was created
• 1968 DSM II multiaxial system of categories was introduced
• 1980 DSM III more detailed criteria and new disorders appeared
• 1987 DSM III R minor revision
• 1994 DSM IV revisions were consolidated
• 2013 DSM V multiaxial system was abandoned, and new research incorporated
• 2022 DSM V TR minor revisions

DSM II – IV Criticisms

• Over-diagnosis and medicalization
• Lack of cultural sensitivity
• Lack of scientific evidence
• Influence of pharmaceutical companies
• Inadequate representation of diverse experiences
• Distortion of clinical priorities

DSM V

• DSM-5 uses a categorical and dimensional approach.
• Considers severity, symptoms, and duration of disorders.
• DSM-5 creates specifiers and subtypes for refining diagnoses.
• Pays attention to gender and cultural differences in mental health diagnoses.

DSM-V Criteria for Schizophrenia

• Requires two or more of specific symptoms for a significant portion of a 1-month period, including delusions, hallucinations, or disorganized speech.
• Level of functioning in major areas is markedly below previous levels.
• Continuous signs of disturbance persist for at least 6 months, including active-phase symptoms and possible prodromal or residual symptoms.
• Schizoaffective disorder and depressive or bipolar disorder with psychotic features are ruled out.
• The disturbance is due to a substance or medical condition.
• If there is a history of autism spectrum disorder, schizophrenia is diagnosed only if prominent delusions or hallucinations are present for at least 1 month.

Problems of Classification and Diagnosis

• Diagnostic conventions vary across cultures.
• Reliability of diagnosis is often poor.
• There is a risk of pathologizing human experience and moral issues.
• The assumption of an underlying biochemical cause remains unproven.
• The efficacy of biochemical treatments is poor.
• Base rates pose challenges.
• Clinical utility of diagnosis is limited.

Early Concerns

• The US-UK diagnostic project revealed differences between US and UK diagnostic concepts.

The Problem of Base Rates

• Ignoring the impact of false positives is a significant problem.

The Problem of Reliability

• Reliability in diagnosis refers to the consistency of measurement or observation.
• Spitzer & Fliess (1974) introduced Cohen’s kappa statistic to correct for the base-rate problem: k = (Po - Pc) / (1 - Pc).
• Po is the proportion of observed agreement between clinicians.
• Pc is the level of agreement expected by chance.
• Kappa values greater than 0.7 are considered ‘satisfactory’.
• The problem of Reliability remains for Adults and Children based on DSM-5 field trials.

Problem of Clinical Utility

• Conventional approaches to psychosis have had little impact on mental health.
• Long-term outcomes for psychosis patients have not improved since the end of WW2.
• Developing countries with poorly resourced mental health services have better outcomes.
• Mental illness should be considered a public health challenge.
• There is little evidence that categorical diagnoses have clinical utility.
• Drug treatments impact a wide variety of conditions, not just their target disorders.
• Despite vast expenditure, classifying mental illness lacks the specificity to precisely direct psychiatric intervention.

Developing Alternative Approaches

• There is widespread agreement that categorical diagnoses are not fit for most scientific and clinical purposes.
• Four approaches are current: quantitative classification, network models, symptom-orientated research, and Research Domain Criteria (NIMH).

Quantitative Classification

• Aims to develop a scientifically valid method of classification using advanced statistical techniques to identify syndromes and test models.

The Five Dimensions Model of Psychosis

• Factor analytic studies on symptoms suggest that all psychotic disorders can be explained by five independent dimensions: positive symptoms, negative symptoms, cognitive disorganization, depression, and mania.

Diagnostic Spectra

• Derived using factor analyses of diagnoses, examining patterns of comorbidity.
• Krueger (1999) found internalizing and externalizing spectra.
• Kessler et al. (2011) supported these findings.
• Kotov et al. (2011) identified a third spectrum of psychosis.
• Three spectra: internalizing (mood), externalizing (behavior), and psychosis.

Factor Analysis

• Studies based on comorbidity between diagnoses suggest a single psychosis spectrum.
• Research based on factor analysis of psychotic symptoms suggests five psychotic dimensions: positive symptoms, negative symptoms, disorganization, depression, and mania.

Hierarchical Models

• Research is converging on hierarchical models similar to biological classification.

Key Features of a Network Model

• Network Structure vs Network State
• Centrality Hypothesis
• Connectivity Hypothesis
• Causality Hypothesis
• Comorbidity Hypothesis

Network Models

• Syndromes may occur because one symptom are causally connected to others in networks.
• Applies to psychosis, depression, anxiety, and trauma.

Network Model Limitations

• There is no statistical test to establish whether a network or a latent variable model best fits the data.
• The structure implies causal relationships between symptoms.
• There are no clinical implications of network models as yet.

The Symptom Approach

• Research focuses on specific symptoms: hallucinations, delusions, thought disorder, negative symptoms, and manic symptoms.
• The goal is to explain each symptom individually.
• Clinicians simply write down a list of symptoms.

Symptom Approach - Clinical Implications

• Clinicians simply note the symptoms listed.
• CBT should be problem-based.
• The therapist's initial task is to have the patient describe the problem, which may not be symptoms.

Summary

• Categorical diagnoses have been used to guide research and treatment for much of psychiatry's history.
• These diagnoses have limited scientific validity or clinical utility.
• Efforts are underway to develop alternative classification systems.
• There is no consensus on the best approach.
• Different systems may suit different purposes.

Explore challenges in psychiatric classification, highlighting the functions of diagnoses in treatment, communication, and research. Reviews the evolution from Kraepelin's work to the DSM, focusing on its role in modern psychiatric practice.