The Science of Depression: Causes, Symptoms, and the Role of Neurotransmitters

I once believed that genetics was the sole cause of depression, but I learned that depression is a multifactorial disorder. This means that various factors can contribute to its development. Additionally, some of these factors may support or exacerbate the onset of depression.

We can classify the causes into four main categories:

A. Biological cause:

• Family history: family history, especially among first-degree relatives, significantly increases the likelihood of depression compared to other factors.
• Neurotransmitter imbalance: These chemical messengers play a significant role in regulating our moods, feelings, sleep, and appetite. An imbalance in these neurotransmitters could result in depression. The cause of this imbalance is not specifically any condition that results in imbalance.
• Hormonal changes: Hormones usually influence each other’s levels and functions, which can be explicitly seen during the menstrual period, where women often experience depression, in addition to depression associated with pregnancy and menopause.
• Brain Structure and Function: Any changes in brain structure and function could result in unfamiliar side effects. For example, changes in specific parts of the brain, such as altered activity in the prefrontal cortex and amygdala, are associated with depression.

B. Psychological Factors:

• Negative thinking: Interestingly, research has found that negative thinking could alter your mood in the long run. It shows that a prolonged period of negative thinking could demotivate you and result in a depressive mood and symptoms.
• Low self-esteem: Negative thinking and low self-esteem usually occur together, and their main effects result in chronic stress, demotivation, loss of interest, and sleep and eating issues; all of these contribute to the development of depression.
• Stress and Trauma: Stress and trauma are among the most common causes of depression, anxiety, and other mental illnesses. Exposure to prolonged stress or traumatic events alters neurotransmitters, which results in the development of depression. 

C. Environmental and Social Factors:

• Life Events and Stressors: Life events resulting in stress and prolonged sadness are common causes. Things like the loss of a loved one or stress related to war, financial issues, or chronic illness can significantly predispose individuals to depression and anxiety.
• Social Isolation and Lack of Support: We are supposed to be together because we need each other, and interestingly, research shows that social isolation and lack of support could predispose us to depression.
• Childhood Adversity: The American Journal of Preventive Medicine has found that childhood experiences such as abuse and neglect are linked to a higher risk of depression and other health problems in adulthood.

D. Other Factors:

• Substance Abuse: Drugs, alcohol, and smoking that interfere with normal brain function significantly lead to abnormal brain function res, result in mental illness, and trigger and exacerbate depressive symptoms.
• Medical Conditions: Medical conditions, specifically chronic illnesses such as diabetes and heart disease, are usually associated with the development of depression and anxiety due to uncertainty and sadness, which result in a depressive mood.

Whatever the cause, the main effects are changes in key role neurotransmitters, alterations in brain function, prolonged stress,  and disruption of the reward system.

However, understanding the exact cause of depression is a crucial step for effective treatment and lifestyle changes that eliminate triggers and root causes.