How a clinician decides the severity of a depression

In order to make the diagnosis of depressive episode, a clinician merely has to be satisfied that there are five or more depressive symptoms from a list of nine, present for at least 2 weeks. It should be remembered that the concept is atheoretical, and is derived from the collective clinical experience of international psychiatrists, who have decided to draw an arbitrary line between what will count as ‘clinically significant’ and what they will regarded as ‘subclinical’.

In order to decide how severe such an episode is, other things must also be taken into account, including suicidal risk, the presence of a history or a family history of depression, and the degree of disability associated with the depressive symptoms. ICD–10 (World Health Organization, 1992) defines three degrees of severity:

1. • F32.0 Mild depressive episode. Depressed mood, loss of interest, increased fatiguability – at least two of these, plus two of the other seven symptoms. None of the symptoms should be present to an intense degree. The minimum episode length is 2 weeks. The individual is usually distressed by the symptoms and has some difficulty continuing with ordinary work and social activities, but does not cease to function completely.

2. • F32.1 Moderate depressive episode. At least two of the above three, plus either three or four other symptoms. Several symptoms are present in marked degree. An individual will usually have considerable difficulty continuing social, work and domestic activities.

3. • F32.2 Severe depressive episode. The sufferer usually shows considerable distress or agitation – unless retardation is a marked feature. Loss of self-esteem and feelings of uselessness or guilt are likely to be prominent and suicide is a distinct danger. A somatic syndrome is usually present. All three of the above three symptoms are present, plus at least four of the others, some of which are of severe intensity. If symptoms are widespread and severe, the diagnosis can be made in less than 2 weeks. It very unlikely that a person with a severe depressive episode could continue social, domestic or work activities, except to a very limited extent.