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Depression and addiction: symptoms (ICD)

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Doctors use an agreed list of symptoms to diagnose mental health problems. You need to know the symptoms of unipolar depression and addiction according to the International Classification of Diseases (ICD).

What is the ICD?

The International Classification of Diseases (ICD) is published by the World Health Organization. It lists illnesses, including mental health problems, with their symptoms, so diagnosis is consistent around the world.
The specification was written when ICD-10 was in use; ICD-11 came into use in 2022 and uses slightly different titles.
Unipolar depression is depression without periods of mania (very high mood). This is different from bipolar disorder.

Depression (ICD-10)

Symptoms must last at least two weeks.
Core symptoms: persistent low mood; loss of interest and enjoyment in usual activities; reduced energy, so the person gets tired easily and is less active.
Other common symptoms: reduced concentration; low self-esteem and self-confidence; feelings of guilt and worthlessness; bleak, pessimistic views of the future; ideas or acts of self-harm or suicide; disturbed sleep; reduced appetite.
Severity (mild, moderate or severe) depends on how many symptoms there are. For example, mild depression needs at least 2 core symptoms and 2 others.
If you ever feel low for a long time, talking to a trusted adult or your GP is a good first step.

Addiction (ICD-10 dependence)

A diagnosis needs three or more of these together at some point in the past year:
Worked example

Sam needs more and more alcohol to feel the same effect, and feels shaky and sick when he stops. Which two ICD features of addiction does he show?

  1. Needing more for the same effect is tolerance.
  2. Feeling physically unwell when stopping is withdrawal.

Answer: Tolerance and withdrawal.

Key idea

The ICD lists symptoms for diagnosis. Depression (at least two weeks) has core symptoms of low mood, loss of interest and reduced energy, plus others such as poor sleep and low self-esteem. Addiction needs three or more of: craving, loss of control, withdrawal, tolerance, neglect of other interests, and persistence despite harm.

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