Depression- clinical features


  • 14-18% lifetime prevalence
  • 20% of cases are chronic
  • Genetic risk
    • Increased risk if first degree relative affected (3x)
    • Twin studies- MZ (27%) vs DZ (12%)
    • Hereditability of major depression is around 70%
  • More common in females than males (2:1) and mean age of onset is 27 years old.


  • Onset can be associated with excess adverse life events- mainly exit events (e.g. death/bereavement, separation etc) or negative early experiences e.g. abuse or neglect.

Diagnostic classification

Depressive episodes

  • ICD-10 splits depressive episodes into mild, moderate and severe depression +/- the presence of somatic or psychotic symptoms.


  • DSM IV splits depression into just minor and major; ICD-10 splits into mild, moderate and severe.

Clinical Features

Symptoms must be clearly abnormal for the individual concerned, it must persist for more than 2 weeks (without previous history of mood disorder), and it should interfere with normal function to a significant degree.

In moderate depression, there should be 2; and in severe depression, all of the following typical symptoms:

  • Low mood to a degree that is definitely abnormal for the patient; present for most of the day; largely uninfluenced by circumstance; and present for at least 2 weeks
  • Loss of interest or pleasure in activities that are usually enjoyable (anhydonia)
  • Decreased energy or increased fatigue

PLUS >=4 (moderate) or >4 (severe) of:

  • Loss of confidence/self esteem
  • Unreasonable feelings of self-reproach or excessive and unreasonable guilt
  • Recurrent thoughts of death/suicide, or any suicidal behaviour
  • Complaints or evidence of diminished ability to think or concentrate e.g. indecisiveness
  • Changes in psychomotor activity, with agitation or retardation (either objective or subjective)
  • Sleep disturbance
  • Change in appetite with corresponding change in weight


Although the diagnosis of severe/moderate/mild depression are made on the number of symptoms, there are various other ways of assessing the severity of depression.

  • Rating scales e.g. Hamilton rating scale for depression; Montomery-Asberg depression scale; Beck depressive inventory (NB Beck’s cognitive triad- negative view of self, others and the future)

Subtypes of depression

Progression / Timeline

The 5 ‘R’s’ are a good way of thinking about it:

  • Response
  • Remission
  • Relapse
  • Recovery
  • Recurrence


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