Depression may be caused by one factor alone or a combination of factors including biological, psychological and environmental (linked to social or family environment) factors.4,8,9
Biological Factors1
We are not certain what causes depression. One of the predominant theories proposes that depression is caused by an imbalance of naturally occurring substances called neurotransmitters in the brain and spinal cord.10
Serotonin and norepinephrine are two neurotransmitters in the brain that appear to be involved in the symptoms of depression.10
Psychological Factors11
Individuals are affected by outside events differently. Each person’s thoughts determine how he or she will experience life, which can affect whether or not they become depressed.11
The way we think about things and view the world often emerges in childhood. For example, a strict and severe upbringing in which negative comments and criticism predominate can shape the way one views the world, in most likely a negative way.11
It is not surprising, therefore, that these ways of looking at the world reinforce the negative effect of difficult situations in life, predisposing people to emotional suffering.11
Environmental Factors11
Depression can often be triggered by very stressful life situations or other factors such as:11
The death of a loved one, a move, a divorce, financial difficulties or job loss.
Social isolation.
Periods of relationship conflict, whether marital or family-related.
Demanding work or a stressful workplace.
Health issues, especially when the person has a chronic health problem.
Sometimes the biggest hurdle to getting better and moving forward is the depression itself. For example, a depressed person often removes themselves from the presence of comforting and encouraging loved ones or ceases to participate in activities of personal interest as result of being depressed, which might further contribute to their condition.11