There is no single cause for depression. In some individuals, stressful life events such as the loss of a job, long-term unemployment, physical health issues, family problems, the death of a loved one, or the end of a close relationship might trigger depression. For other people, there is no obvious cause.
Experts no longer believe that depression is caused by a ‘chemical imbalance’, but that the risk for developing depression is more likely to be related to a combination of a person’s genes, biology, life experiences, stress and thinking style.
For many people, genetics may play a part, with research suggesting around 30-40% of the risk for developing depression may be due to genetic factors.
Research has found some differences in areas of the brain, and brain activity in people with depression compared to people without. The areas of the brain that differ relate to emotional responses and emotion regulation, the interpretation of information (with a bias for negative information) and response to stress. Interestingly, many of these differences decrease with treatment.
Stressful life events
Research suggests that the greater the number of stressful life events a person experiences, the greater their chances of developing depression. Early life stress and trauma can also increase the likelihood of developing depression later in life.
People who tend to dwell on negative events, worry excessively or hold a more negative view of themselves, the world, or the future are more prone to depression.
A person may be depressed if, for more than two weeks, they have experienced either (or both) of the following:
For a diagnosis of depression, a psychologist will look for specific symptoms that impact on a person’s daily life. Some of these include changes to their appetite and sleep, lethargy, worry and negative thinking patterns.