The causes of depression are unique to each individual and very complex. Tendencies toward depression can run in families, pointing to a genetic link in many cases. The roots of a depressive episode may lie in one's childhood environment, or in a traumatic event in later life. It is generally believed, however, that neurochemical imbalances and disruptions in the brain are above all responsible for triggering depressive symptoms. The good news is that there are several effective treatments available to fight depression, and that most sufferers begin feeling better within several weeks of beginning therapy.