Diagnosis and Classification of Schizophrenia

Schizophrenia (SCZ) Overview

• SCZ is a mental illness typically manifesting in late adolescence or early adulthood.
• Associated with psychosis; patients may have no concept of reality due to a personality breakdown.
• Culturally universal; symptoms and incidence vary significantly across cultures.
• Approximately 1% of the global population develops SCZ during their lifetime.

Diagnostic Criteria: DSM-5 vs. ICD-10

• DSM-5 requires at least one positive symptom for diagnosis.
• ICD-10 allows diagnosis with two or more negative symptoms.

Positive Symptoms

• These represent additional experiences beyond ordinary existence.

Hallucinations

• Involve sensory experiences without real external stimuli.
• Can affect any sense, including auditory hallucinations (e.g., hearing voices).

Delusions

• Firmly held false beliefs, often illogical, with no supportive evidence.
• Common types include delusions of persecution, grandeur, or control.

Negative Symptoms

• Characterized by a loss of standard abilities and experiences.

Avolition

• A significant decrease in motivation for everyday tasks such as work and personal care.

Speech Poverty

• Refers to reduced amount or quality of speech and possible delays in conversation.
• DSM emphasizes speech disorganization and incoherence.

Diagnostic Issues

• Major challenges include reliability, validity, co-morbidity, symptom overlap, as well as cultural and gender bias.

Reliability

• Relates to the consistency of SCZ diagnoses across different evaluators (inter-rater reliability).

Validity

• Concerns if diagnosis and classification methods successfully measure what they are meant to.

Key Study: Rosenhan (1973)

• Eight confederates posed as pseudo-patients in 12 hospitals, claiming to hear voices ("empty, hollow, thud").
• 11 were diagnosed with SCZ; a further patient was diagnosed with manic-depression.
• Staff failed to recognize the sanity of the pseudo-patients, questioning the reliability of SCZ diagnoses.

Co-morbidity

• Refers to the co-occurrence of SCZ with other mental illnesses, complicating diagnosis and treatment.
• Raises questions about the validity of classifications when severe depression resembles SCZ symptoms.

Research by Buckley et al. (2009)

• Around 50% of SCZ patients also experienced depression, while 47% had substance abuse issues.
• PTSD was found in 29% and OCD in 23% of SCZ patients, highlighting common co-morbidity with other disorders.

Symptom Overlap

• SCZ shares symptoms with bipolar disorder, complicating diagnosis and classification validity.
• Example: Delusions as a positive symptom in both disorders.
• Research also found that individuals with Dissociative Identity Disorder exhibit more SCZ symptoms than those diagnosed with SCZ.

Implications of Misdiagnosis

• Misdiagnosis due to symptom overlap can delay relevant treatment, leading to potential suffering and higher suicide rates.
• Addressing symptom overlap issues could save lives and reduce healthcare costs.

Cultural Bias in Diagnosis

• Significant diagnosis variations suggest cultural influences, with ethnic minority symptoms often misinterpreted.
• Harrison et al. (1984) noted overdiagnosis of SCZ in West Indian individuals by white doctors.
• Copeland et al. (1971) demonstrated contrasting diagnoses across countries, highlighting reliability concerns in SCZ diagnoses.