Major depressive disorder affects over 7% of the U.S. population age 18 and older in a given year. That means more than 17 million people experience symptoms of depression and reduced quality of life each year.

Since depression is the leading cause of disability worldwide and a significant contributor to the global burden of disease, those in need of help must receive the treatment they deserve. Among those who seek treatment, up to 80% show an improvement in their symptoms within four to six weeks. However, despite these high success rates, nearly two out of three people suffering from depression do not actively seek or receive proper treatment.¹

If you are one of the millions of people suffering from depression, you may be wondering, why me? Is it possible that some people are more prone to suffer from depression than others? Is depression genetic, and if so, will that play a role in your treatment plan? This guide dives deeper into some of the potential causes of depression.

Discover more about depression and mood disorders.

The Biology of Depression

There is no single cause of depression — it is an incredibly complex condition. However, research shows that your biology is often a significant contributing factor. Scientists have looked at patterns of illnesses in families to estimate heritability.

To determine how much genetics contribute to depression, researchers often study twins. Identical twins share 100% of their genes, while non-identical twins share 50%. Heritability for depression is likely 40% to 50% based on twin studies and may even be higher for severe depression.

However, researchers are still unclear about how much of the cause is genetic.

Since so many other variables can contribute to the development of depression, there are many possible links to explore. For example, if your parent or sibling has major depression, you will probably be two or three times more likely to develop depression compared with the general population.²

So, is depression genetic?

A recent large study looked at the genetic and health records of 1.2 million people from four data banks. It found 178 possible gene variants linked to major depression. Of course, this research is rather complex, as these variants influence different areas of the brain and associated brain chemicals, including the hypothalamus and glutamate system.³

Learn more about what happens to the brain during depression. 

Considering Environmental Variables

Again, the role that environmental factors play is complex as there are so many possible variables.

One of the most significant non-chemical environmental risk factors is stress. This stress can be psychological or physiological. For example, psychological stress can develop following a divorce, unemployment, financial issues, etc. This psychological stress can lead to physiological responses, including changes in nervous, immune, and endocrine systems.⁴

Childhood trauma is another key area of interest, including childhood abuse or a significant loss. Both physical and emotional trauma can trigger depression based on how a person processes emotions following such events. One study found that among 349 chronically depressed patients, 75.6% reported a history of childhood trauma.

Chemical pollutants are also being studied, as these chemicals are known to harm the human body and brain. Since we live in the post-industrial era, people are exposed to synthetic chemicals daily. These chemicals are found in the water, air, and modern food systems.

What About Social Factors?

There is an overlap between environmental and social factors, including everything from divorce to neglect, the death of a loved one to social isolation. That is because social factors are any social aspect that influences your behavior and quality of life, including the influence of family and your community.

In most cases, these factors are associated with some level of trauma, resulting in high-stress levels. These stressors can trigger depression, especially among those predisposed to mood disorders.

In some cases, events aren’t negative. For example, having a baby can trigger depression in some individuals. This example showcases how complex depression is, as many variables can contribute to postpartum depression. Just some of the risk factors associated with this type of depression include a previous history of depression and a history of sexual abuse.⁵ Like all types of depression, each individual is unique — and a combination of unique variables is likely at play.

The Link Between Depression and Lifestyle Factors

There is also a strong link between depression and individual lifestyle factors, including sleep, diet, physical activity, and substance use. One of the reasons this association is so strong is because optimal physical health is a critical foundation of positive mental health.

For this reason, holistic treatment typically involves various options that target lifestyle variables. For example, nutritional psychiatry focuses on the crucial relationship between the mind and body. Research shows that a diet with a high intake of fruits, vegetables, whole grain, fish, olive oil, and low-fat dairy, plus low intakes of animal foods, can help reduce your risk of depression.

Many lifestyle factors also contribute to worsening symptoms, with many researchers wondering if one causes the other. For example, does substance abuse cause depression, or does depression lead to substance abuse?

There isn’t a simple answer to this question, as substance abuse often triggers or intensifies feelings of depression, resulting in a cycle of dependence and addiction. Depression often makes people want to take substances, leading to more significant, ongoing symptoms. In these cases, individuals are often treated for co-occurring disorders.

Transformations Treatment Center Can Help

It’s unclear what causes depression. However, most researchers believe it is a complex combination of variables — and these variables can differ from one person to the next. That is why you need to seek professional, evidence-based support when dealing with depression. There is no “one-size-fits-all” solution. You need to seek a treatment plan based on your individual needs and goals.

Whether you or your loved one are suffering from depression, Transformations Treatment Center offers comprehensive, individualized treatment. We offer programs that focus on holistic treatment, healing you emotionally, mentally, physically, and spiritually.

Ready to take the next step? Contact us to discuss your personalized needs today!