Screening for depression

Many people with depression do not see a mental health specialist and may not receive a formal diagnosis. Still, it is possible to recognise depression and prompt further assessment by using simple screening tools.

These are usually brief questionnaires with statements that reflect different symptoms of depression. Each statement is scored by the person who completes it. The total score from all the answers indicates whether depression is likely to be present and whether it is likely to be mild, moderate or severe.

The 9-item Patient Health Questionnaire (PHQ-9) (Kroenke et al, 2001) is one such tool commonly used. You can find out more here: more information about the PHQ9.

The PHQ-9 has been translated into almost 50 languages, including British Sign Language (BSL); however, not all of these translated versions have been validated through research studies. When such studies took place to validate different language versions of the PHQ-9, their results showed that PHQ-9 remained a valid measure of depression after translation, but depression symptom scores were not always equivalent across different languages.

In sum, general practitioners, health and charity workers, teachers and other professionals can use depression screening tools, because they are:

• Quick and easy to administer without specialist training.
• Readily available, often without charge.
• Easy to understand and to interpret their scores.
• Available in different languages.

A word of caution

A screening tool on its own does not make a diagnosis of depression. Screening tools can tell us whether it is worth having a follow-up assessment or a consultation with a mental health professional to confirm a diagnosis. To make a diagnosis of depression, a health professional takes into account the impact of the symptoms in a person’s life, considers for how long the symptoms have been present and whether they change over time, and asks supplementary questions to rule out other physical or mental health conditions that may be expressed with the same symptoms as depression.

Routine screening for depression is not recommended for the general population because normal mood variations can mislead us in thinking that people may have depression when they do not. Screening tools are used as a way of gauging the likelihood and severity of depression when people feel that their low mood persists for a long time and has a major impact in their lives.