SCHIZOPHRENIA ( reliability & validity in diagnosis and classification)

Question 1

Outline DSM-5 as a classification system for diagnosing schizophrenia

Answer 1

DSM-5 are the two main systems used to classify and diagnose schizophrenia. Criteria include symptoms like delusions , hallucinations , disorganised speech , and catatonic behaviour usually persisiting for at least a month

Question 2

Explain how reliability in diagnosis may be tested

Answer 2

Diagnostic reliability means that a diagnosis of schizophrenia must be repeatable ( inter-rater reliability) measured by a statistic called kappa score ( 1 indicating perfect inter-rater agreement)

Question 3

Assess reliability based on gender bias , symptom overlap and co-morbidity

Answer 3

Gender bias - in diagnosis when males and females are not treated equally , leading to diagnostic distortion. Research shows how men are more likely to be diagnosed than women

Symptom overlap - occurs when symptoms of schz are also found in other mental disorders , reducing diagnostic accuracy eg. hallucinations and delusions are also present in bipolar disorder

Co-morbidity - Refers to when a person has more than one disorder at the same time. Common co-morbid conditions include depression , anxiety and substance abuse. This complicates diagnosis .

Question 4

Evaluation of reliability & validity

Answer 4

STRENGTHS :

Use of standardised diagnostic criteria : systems like DSM-5 provide clear and specific criteria , which improves inter-rater reliability. Jakobsen et al found 98% concordance using ICD-10 , indicating high reliability

Predictive validity exists to some extent : Some treatments eg. antipsychotic drugs work for diagnosed individuals , suggesting predictive validity. However not all patients respond to the same treatment - indicating variability in underlying conditions

LIMITATIONS :

Low validity : overlap with other symptoms of other mental disorders , lowering construct validity. Co-morbidity is a problem many patients with schizophrenia also have depression or substance abuse issues.

Cultural bias : Diagnosis is influenced by cultural norms and expectations : Afro-Caribbean individuals in the UK are more likely to be diagnosed with schizophrenia than white individuals. Suggesting culture bias can reduce reliability and validity.

Gender bias : Males are more likely diagnosed than females , possibly due to gender stereotypes or under-detection in women . Suggests gender bias affects diagnostic validity