What is a depressive disorder?

What causes depressive disorders?

Page last updated: May 2007

Often there are many interrelated factors associated with depression.

Genetic factors

It is well established that the tendency to develop depression runs in families. This is similar to a predisposition to other illnesses, such as diabetes and heart disease.

Biochemical factors

Depressive disorders are thought to be due, in part, to a chemical imbalance in the brain. Anti-depressant medication treats this imbalance.


Stress is associated with the development of depressive disorders, particularly personal tragedies or disasters. Depressive disorders are more common at certain stages of life that involve major life transitions, such as childbirth, menopause and bereavement. Consequently, it is more common in young adults, women, older adults, and people with physical health problems.


People with certain temperaments are more prone to depressive symptoms.

Depression commonly occurs in people who are highly anxious, sensitive, emotional, and react strongly to and are easily upset by events in their lives.

People who are perfectionists and selfcritical, and who set high standards for themselves and others, are vulnerable to depression. Those who are very dependent on other people are also susceptible to depression if they are let down.

In contrast, people who are optimistic and who practice thinking positive thoughts tend to be protected from depression.

Alcohol and other drug use

Harmful alcohol and other drug use makes people highly susceptible to depression. This also contributes to a high risk of suicide for people with depressive disorders.