Diagnosing Mental Illnesses

The 4 D's

The 4 D's are used by psychiatrists as a tool to decide whether the behaviour of a patient is abnormal.

1. Deviance - The extent to which the behaviour is rare in society (outside of social/cultural norms). If it is rare enough and deviant from the norm, then this could suggest that a clinical disorder is present. This can be measured using statistics and normal distribution.

2. Dysfunction - If the behaviour is significantly interfering with the person's life. The clinician must discuss every aspect of their life to assess this, and it may be there while it is not immediately obvious.

3. Distress - The extent to which the behaviour is causing upset to the individual. The patient can be extremely distressed but still able to function normally. The subjective experiences of the patient is very important here, which could make it difficult to measure.

4. Danger - The patient's behaviour has to be assessed unter two key elements of danger; danger to themselves and danger to others.

The IDC (International Classification of Diseases)

• First drafted by the World Health Organisation in 1948. The most recent is the ICD-10 which was published in 1992.
• Section F of the ICD is specific to mental health disorders. Within that section disorders are grouped as part of a family, for example mood disorders. 
• Clinicians use the system within the ICD to guide their diagnosis through a clinical interview. This requires expertise of the clinician as mental disorders are often not clearly presented. 
• It provides a basis on which to make a judgement, giving details of likely symptoms for each…