Reliability of diagnoses

Reliability & validity

• same diagnosis should be made by two or more clinicians

• Validity means that the correct diagnosis is made ( no false positives or negatives)

DSM vs ICD

DSM: 2 symptoms present, at least one positive

ICD: 1 key symptom present

Risk of misdiagnoses because:

• No core symptoms which are common to all people with sz

• No objective test to verify if a diagnosis of SZ is correct

• The description of symptoms and interpretation by clinicians are subjective. There may also be culture and gender bias.

Rosenhan’s Being sane in insane places

• 7 ppt (students) - 3 women & 4 men visited 12 psychiatric hospitals across 5 states

• Had to fake a single symptom of hearing a voice

• Once admitted, tell them its gone and ask to leave

FINDINGS: None of the pseudo-patients were spotted, longest stayed for 2 months. Suggests lack of testing

Changes made as a result

widespread distrust of accurate diagnoses of metal disorders

Revision of classification systems for more in-depth overview

More human treatment of people with metal distores in intuitions.

Co-morbidity

When two disorders frequently occurs together (Sz & Bp). Makes it harder to tell the difference which reduces validity of disgnoses & classification.

Buckley et al: 50% of patients with a diagnosis of schizophrenia also have depression or substance abuse. PTSD also occurred in 29% of cases and OCD in 23%.

Symptom overlap

When disorders share the same symptoms (eg. avoiltion).

Serper et al: assessed patients with co-morbid schizophrenia and cocaine abuse, despite overlap in symptoms, t was actually possible to make accurate diagnoses.

Gender & Culture bias

• More men diagnosed with sz since 1980s → could be genetic or that women are better at communicating / seeking support. Underdiagnoses of women could prevent them receiving treatment

• Some symptoms have different meaning. In Haiti, hearing voices is communication with ancestors. African-British are 9x more likely to be diagnosed due to over-interpretation of symptoms