If you're depressed, it might not be easy to figure out why. In most cases, depression doesn't have a single cause. Instead, it results from a mix of things -- your genes, events in your past, your current circumstances, and other risk factors.
Biology. We still don't know exactly what happens in the brain when people become depressed. But studies show that certain parts of the brain don't seem to be working normally. Depression might also be affected by changes in the functioning of certain chemicals in the brain.
Genetics. Researchers know that if depression runs in your family, you have a higher chance of becoming depressed.
Gender. Women are about twice as likely as men to become depressed. No one's sure why. The hormonal changes that women go through at different times of their lives may be a factor.
Age. People who are elderly are at higher risk of depression. That can be compounded by other factors, such as living alone and having a lack of social support.
Trauma and grief. Trauma such as violence or physical or emotional abuse -- whether it's early in life or more recent -- can trigger depression in people who are biologically vulnerable to it. Grief after the death of a friend or loved one is a normal emotion, but like all forms of loss, it can sometimes lead to clinical depression.
Changes and stressful events. It's not surprising that people might feel sad or down during stressful times -- such as during a divorce or while caring for a sick relative. Yet even positive changes -- like getting married or starting a new job -- can sometimes trigger a clinical depressive syndrome that is more than just normal sadness.
Medications and substances. Many prescription drugs can cause symptoms of depression. Alcohol or substance abuse is common in depressed people. It often makes their condition worse by causing or worsening mood symptoms or interfering with the effects of medications prescribed to treat depression.
Some people have a clear sense of why they become depressed. Others don't. The most important thing to remember is that there doesn't need to be a "reason" to have clinical depression, and depression is not anyone's fault. It's not a flaw in your character. It's a disease that can affect anyone -- and regardless of the cause, there are many good ways to treat it.