Definition of depression/symptoms

Depression is a human experience that has various forms. In its more subtle form, depression is a feeling of sadness, most often related to loss or sense of helplessness about a particular event. Moderately intense experiences of depression often involve biological, psychological and social elements. Depression can be assessed using responses to a questionnaire or a rating scale.


A period of at least 2 weeks, in which at least five of the following symptoms are present most of the day, nearly every day, and of which at least one is the first or second listed symptoms: 

  1. Sadness (or irritability in children)
  2. Loss of interest or pleasure in usual activities 
  3. Changes in appetite (increased or decreased) or weight change
  4. Disturbed sleep (insomnia or hypersomnia)
  5. Psychomotor agitation or retardation (pacing, tapping, fast talking, or slowed physical or emotional reactions)
  6. Fatigue or loss of energy 
  7. Feelings of guilt, self-blame
  8. Decreased ability to concentrate or make decisions 
  9. Thinking about or planning suicide or suicidal behavior. (Dobson, Dozois)

What causes Depression?

Diagram Adapted from Risk Factors in Depression Chapter One: Introduction: Assessing Risk and Resilience Factors in Models of Depression by Dobson, K., and Dozois, D.
Dobson, K., & Dozois, D. (2009, December 17). Introduction: Assessing risk and resilience factors in models of depression. Retrieved March 24, 2021, from
Auerbach, R., Admon, R., & Pizzagali, D. (2014). Adolescent depression: Stress and reward dysfunction. Retrieved March 24, 2021, from