1. Genetics:
People with a history of depression in their family have a slightly higher chance of becoming depressed. However, genetics alone does not cause depression.

2. Psychology:
The way you have learned to deal with problems, may contribute to depression. If you are the type of person who has a low opinion of yourself and worries a lot, if you are overly dependent on others, if you are a perfectionist and expect too much from yourself or others, or if you tend to hide your feelings, you may be at greater risk of becoming depressed.

3. Life Events:
Early childhood trauma and losses (such as the death or separation of parents) or adult life events (such as the death of a loved one, divorce, loss of a job, retirement, serious financial problems and family conflict) can lead to depression.

4. Biological Factors:
Hormonal or chemical imbalances in the brain may cause depression.