Constitutional factors: In some families depressive disorders occur more frequently than in others. This may imply that there is a hereditary biological disposition there.
Biochemical factors: A depressive disorder is related to lack of neurotransmitters in brain. These participate in transmission of neural impulses in brain.
Childhood development conditions: A loss of an important person in childhood (death, divorce of parents), lack of care, mistreatment or on the contrary pampering may be related to a development of depression in adult age. Moreover, a parent with depression can become a model of behaviour and thinking for a child.
Psychological factors: Low self-confidence, excessive dependence on acceptance and approval by other people, inability to accept and express criticism and anger are the most frequent psychological factors that result in depressive disorder.
Physical factors: A depressive disorder may be related to postpartum hormonal changes, decreased function of the thyroid, high pressure, diabetes and a number of other physical disorders.
Medicaments, drugs, alcohol: Depression and anxiety may result from taking certain medicaments, or excessive consumption of alcohol, and drug addiction.
Stressing life events: Stressing life events, like a loss of a close person, change of a life situation or role, conflict in family or at school, can trigger a depression.