A03 - Reliability + Validity in Diagnosis and Classification

• One problem of reliability and validity of the classification and diagnosis of sz is that there is often ‘Symptom overlap’. This is where two or more conditions share similar symptoms. For example, both sz and depression involve negative symptoms such as avolition. This questions the validity and reliability because an individual may be diagnosed with the wrong disorder. This is an issue as doctors may not be diagnosing sz correctly, and therefore individuals may not receive appropriate treatment. This weakens the validity and reliability as it negatively affects its accuracy and consistency.
• A further problem with the reliability and validity of the diagnosis and classification of schizophrenia is ‘Co-morbidity’. This is where two illnesses/conditions occur at the same time. For example, Buckley et al concluded that 50% of patients diagnosed with schizophrenia also have a diagnosis of depression and 23% of patients diagnosed with schizophrenia are diagnosed with OCD. This questions the validity and reliability of classification and diagnosis of schizophrenia, because the two conditions may be better seen as one and doctors may diagnose the wrong condition.
• Another issue with the validity of the diagnosis and classification of sz is gender bias in diagnosis. Men have often been diagnosed with sz more than women. This may be because men are more genetically vulnerable to developing sz than women. However, it could be because females with sz typically function better than men, being more likely to work and therefore their symptoms may be masked by good interpersonal skills. Questioning the validity and reliability of the classification and diagnosis of schizophrenia as women who share similar symptoms as men may not receive the same diagnosis.