Major Depressive Disorder

Major Depressive Disorder requires a minimum of five of the following symptoms. The symptoms need to be prominent and to be present for at least two weeks. Symptoms 1 and 2 MUST be present.

1. Depressed mood present most of the day nearly
      every day for the two weeks.
2. Loss of interest or inability to derive any pleasure
      (most of the day nearly every day).
3. Significant weight change (> 5% of body weight
      loss or gain) or significant change (loss or
      gain) in appetite nearly every day.
4. Sleep disturbance: insomnia (such as difficulty
      falling asleep, frequent awakening,
      earlier-than-usual awakening despite fatigue)
      or hypersomnia (excessive sleeping).
5. Physical signs of either agitation/restlessness
      or of retardation/slowness.
6. Lack of energy or significant fatigue.
7. Feelings and thoughts of worthlessness
      or excessive guilt.
8. Impaired concentration or indecisiveness.
9. Suicidality (ranging from thoughts to attempts).

Source:  The Diagnostic and Statistical Manual - Fourth Edition
                 (DSM-IV) of the AmericanPsychiatric Association (1994)