There are several possible causes of depression. It can be a combination of factors, and some people might relate to these factors without ever developing depression.
People learn what they consider “normal” from the environment in which they are raised. If a person is raised around others with depression or a pessimistic attitude, they will adopt these outlooks as well. They will also have no good examples of coping skills to model.
Stressful life events such as failing a class, moving far away from friends or family, or ending a serious relationship can bring on an episode of depression. While most people will experience sadness over such events, people with a tendency towards depression will react more strongly, especially in the absence of appropriate coping skills or a support system.
Other Medical Illnesses
The stress of being ill can increase the likelihood that someone will become depressed. Certain illnesses in particular seem to be linked to depression. These include under-active thyroid, heart attack, stroke, and cancer. In some cases it is possible that medications prescribed for certain illnesses put a person at a greater risk for depression.
Women are twice as likely as men to develop depression. Researchers are not certain as to why, but it is believed that it might simply be that women are more likely to report being depressed. Women are also more likely to suffer from anxiety, which might also explain why they develop depression more often than men.
It is believed that an imbalance of neurotransmitters in the brain causes depression in some cases. Serotonin, norepinephrine, and dopamine are chemical messengers that operate within the brain to influence mood. If these get out of balance, a person can become more sensitive to the onset of depression.
Research shows that people with a family history of depression are more likely to develop depression themselves. This is especially true in the case of bipolar disorder. In fact, people with a family history of depression are 2 to 3 times more likely to develop depression than those with no genetic predisposition.
People who have unrealistically high standards for themselves or suffer from a persistent inability to be satisfied with outcomes due to perfectionism have been shown to be more likely to suffer from depression. When stressful situations present themselves, perfectionists have more difficulty coping, and this can increase the risk of depression in these situations.
Often times, poor coping skills compound these issues and intensify the problems individuals are experiencing. When people perceive a problem and focus on the issues surrounding that situation, the problem can seem to grow. Excessive worry can become debilitating and eventually turn into depression.