According to the definitions of most medical, psychological and psychiatric bodies, there is a commonality in the diagnosis of depression.
Most depression tests have a very similar framework. Almost without exception, clinical depression will be diagnosed if a certain number of feelings, that are signs of depression, are present over a certain period of time.
Current theory suggests those clinical depression results from complex interactions between brain chemicals and hormones that influence a person's energy level, feelings, sleeping and eating habits. These chemical interactions are linked to many complex causes--a person's family history of illness, biochemical and psychological make-up, prolonged stress, and traumatic life crisis such as death of a loved one, job loss, or divorce. Following are some of the common symptoms of clinical depression:
Markedly diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day.
Significant weight loss when not dieting or weight gain, or decrease or increase in appetite nearly every day. Note: In children, consider failure to make expected weight gains.
Insomnia or hypersomnia nearly every day
Psychomotor agitation or retardation nearly every day
Fatigue or loss of energy nearly every day
Feelings of worthlessness or excessive or inappropriate guilt (which may be delusional) nearly every day.
Exhaustion on waking
Disrupted sleep, sometimes through upsetting dreams
Early morning waking and difficulty getting back to sleep
Doing less of what they used to enjoy
Difficulty concentrating during the day
Improved energy as the day goes on
Anxious worrying and intrusive upsetting thoughts
Becoming emotional or upset for no particular reason
Shortness of temper, or irritability
Restlessness or decreased activity noticed by others
Thoughts of suicide or death
Teenagers may show depression by taking more risks and/or showing less concern for their own safety.