According to Standford University, “At least 10% of people in the U.S. will experience major depressive disorder at some point in their lives. Two times as many women as men experience major depression.”
Depression is a serious mood disorder that can cause persistent feelings of sadness and loss of interest in normal day-to-day activities. Also known as MDD, Major Depressive Disorder or clinical depression, “it affects how you feel, think and behave and can lead to a variety of emotional and physical problems.” At its worst, you may sometimes feel as if life isn't worth living. Unlike experiencing everyday sadness, depression requires long-term treatment, with medications or psychotherapy.
Where Does MDD Come From?
Because so many people in the United States experience depression or a depressive episode throughout their lives, many researchers wonder how much of the condition is hereditary. Standford explains, “Scientists look at patterns of illness in families to estimate what percentage of their cause is due to genes. To do this they find twins both identical and fraternal. If genes are part of the cause, we expect a patient’s identical twin to have a much higher risk of disease than a patient’s non-identical twin. That is the case for major depression. They determined heritability is probably 40-50%."
This means that in cases of MDD, 50% of patients have inherited it while 50% are unrelated to genes (psychological or physical factors).
The reality? Researchers have not completely determined the cause for MDD. “If someone has a parent or sibling with major depression, that person probably has a 2- or 3-times greater risk of developing depression compared with the average person (or around 20-30% instead of 10%).”
Is There a Depression Gene?
While some diseases are caused by a single defective gene like cystic fibrosis, muscular dystrophy, and Huntington’s disease, depression is not the same. Rather than there being a singular gene that causes depression, scientists have determined that there is a combination of “genetic changes that predispose some people to become ill.” It is not one gene, but rather a combination of genes and other factors that make depression more likely in those with a genetic predisposition. “So, no one simply “inherits” depression from their mother or father. Each person inherits a unique combination of genes from their mother and father, and certain combinations can predispose to a particular illness.”
Mood and Genes
Every part of your body, including your brain, is controlled, and influenced by genes. According to Harvard Health, “throughout life, different genes turn on and off, so that — in the best case — they make the right proteins at the right time. But if the genes get it wrong, they can alter your biology in a way that results in your mood becoming unstable.” Bipolar Disorder research has shown that there is a stronger genetic component for this mood disorder than those suffering simply from Major Depressive Disorder, where patients are 60%-80% more likely to inherit the condition when there is a genetic component. This has led scientists to really hone in on gene research to better determine what combinations are triggering MDD.
Some factors that impact our mood as well as our genes include:
- Stressful life events
- General temperament
- Early loss
- Trauma
The field is still actively researching major depressive disorder and how it impacts our bodies and brains. We don’t quite have the answers yet to understand exactly where it is coming from or what causes it. We know that genes play a role, but the field is still figuring out how. If you have a consistent depressed mood and are struggling, seek professional help from a doctor or therapist. You do not have to suffer alone.