Depression

Depression is more than sadness — it is a persistent low mood or loss of interest lasting at least two weeks, often with changes in sleep, appetite, energy, and concentration.

Definition

Depression (major depressive disorder) is a common mood condition marked by persistent sadness or loss of pleasure, along with physical and cognitive symptoms. It ranges from mild to severe. Screening tools like the PHQ-9 measure symptom severity; a clinician diagnoses depression after a full assessment.

What it can feel like

  • Low mood or emptiness most of the day.
  • Loss of interest in activities you used to enjoy.
  • Changes in sleep or appetite.
  • Fatigue, guilt, or difficulty concentrating.

Related screening tests on LuriaLab

Related glossary terms

Veelgestelde vragen

What PHQ-9 score indicates depression?

PHQ-9 scores range from 0 to 27, with bands from minimal to severe. Higher scores suggest more symptoms; a clinician interprets results in context.

Is depression the same as feeling sad?

No. Sadness is a normal emotion. Depression is persistent, affects many areas of life, and often includes physical and cognitive symptoms lasting two weeks or more.

When should I seek help for depression?

Consider professional support if low mood persists, affects daily functioning, or includes thoughts of self-harm. In a crisis, contact local emergency services or a crisis line.

Sources

  • Kroenke K, Spitzer RL, Williams JBW. PHQ-9 validation
  • WHO — depression fact sheet

Last reviewed: 2026-07-02. Screening tools on LuriaLab are for education only and do not provide a diagnosis.