Depression does not have a single cause. Several factors or a combination of factors may contribute to depression. A person’s life experience, genetic inheritance, age, sex, brain chemistry imbalance, hormonal changes, substance abuse and other illnesses all may play significant roles in the development of depression.
Genetics: People with a biological (family) history of depression may be more likely to develop it than those whose families do not.
Brain chemistry: People with depression are thought to have a different brain chemistry than those without the illness.
Attitude: People with a pessimistic outlook on life and low self-esteem who are easily overwhelmed by stress are more likely to develop depression.
Gender: Women experience depression twice as often as men. While a specific explanation of this is unclear, hormonal changes in women that occur during menstruation, pregnancy, childbirth and menopause are thought to be possibilities.
Life Situations: Difficult life events or traumas such as emotional, physical, sexual or verbal abuse; continuous exposure to violence; financial problems or poverty; inappropriate or unclear expectations; maternal separation; family addiction; death of a loved one; neglect; divorce; illness; or racism may all contribute to depression.
During or After Pregnancy (Postpartum):Depression may be associated with the delivery of a child. Studies show that 15-20% of new mothers and 10% of new fathers experience some form of perinatal mood disorder which occurs during pregnancy until up to two years after a baby is born, and includes depression, anxiety, psychosis, bipolar disorder, obsessive compulsive disorder (OCD) and post-traumatic stress disorder (PTSD). Postpartum depression is different from the "baby blues" both by its duration and debilitating effects.
Illnesses: Depression often coexists with other illnesses that precede, follow, cause or are a consequence of the depression. These include mental health conditions, substance use, and serious medical illnesses.