Depression can be caused by a combination of genetic, biological, environmental and psychological factors. People who have gone through adverse life events (unemployment, bereavement, traumatic events) are more likely to develop depression. Depression can, in turn, lead to more stress and dysfunction and worsen the affected person’s life situation and the depression itself.

Some common causes include:

Genetic Factors

• Family history of depression or other mental health conditions can increase the risk. 

Biological Factors

• Imbalances in brain chemicals (neurotransmitters) like serotonin, dopamine and norepinephrine. 
• Hormonal changes, such as thyroid problems or postpartum depression
• Chronic medical conditions, such as diabetes, heart disease or chronic pain.

Environmental Factors 

• Traumatic or stressful life events, such as bereavement, divorce, financial problems or job loss.
• Prolonged exposure to stressful situations, such as an abusive relationship or a highly stressful job.

Psychological Factors

• Personality traits, such as low self-esteem or being overly self-critical. 
• History of other mental health disorders, such as anxiety or post-traumatic stress disorder (PTSD). 

Lifestyle Factors 

• Substance abuse, including alcohol and drugs, which can exacerbate depression.
• Poor diet, lack of exercise and insufficient sleep. 

Social Factors 

• Isolation or lack of social support.
• Difficulties in relationships or social environments.