About 7% of adults and 13% of adolescents report having had at least one episode in which they experienced depression symptoms. Exactly what causes depression is unclear, but is depression genetic? We’ve asked Massachusetts General Hospital psychiatrist David Mischoulon, MD, PhD, to offer insight into this question and others.
What Is Depression?
Depression is a mood disorder that can cause persistent feelings of sadness and hopelessness, as well as a loss of interest in people and activities you once enjoyed.
Other depression symptoms can include:
- Changes in eating and/or sleeping habits
- Increased agitation, irritation, and impatience
- Unhealthy alcohol or drug use
- Reckless judgment and decision-making
- Thoughts of harming others and/or yourself
- Fatigue or lack of energy
- Feelings of worthlessness
Sometimes friends and loved ones notice signs of depression before an individual recognizes depression symptoms in themselves.
What Causes Depression?
The answer to the question “is depression genetic” is complicated and somewhat elusive. It’s important to understand that while no one “inherits” depression from a parent, everyone inherits a unique set of genes from their parents. Certain combinations of genes can predispose a person to any number of health issues, including depression. Research suggests that someone with a first-degree relative (parent or sibling) with depression has a twofold to threefold greater risk of experiencing depression symptoms compared with someone in the general public. Some studies have also suggested that genetics may play a role in as much as 40% to 50% of depression cases.
But even with a genetic load, the odds are still in your favor against ever developing depression. Plenty of people who have a first-degree relative with depression never show signs of depression. Conversely, individuals with no family history of depression can still develop this common mood disorder.
Depression: More Than One Disease?
One reason why it’s challenging to determine genetic risk factors for depression is that it’s possible depression isn’t a single disease. If it’s not one disorder, then what is depression? Some researchers believe that “depression” may actually include multiple disorders with similar symptoms and signs of depression. Each of these disorders could have its own genetic risk factors. Genetic variations related to depression also may differ between men and women.
Certainly, many nongenetic factors have been implicated in the development and progression of depression. They range from substance use and medication side effects to the onset of chronic illness and stressful life events (divorce, childhood neglect or abuse, and the loss of a loved one, among others). Social isolation, financial woes, and family or relationship difficulties can also precipitate the onset of depression symptoms.
Many scientists believe that what causes depression is a combination of environmental factors and multiple genes interacting with each other. Understanding more about the causes of depression, including the role of genetics, is an active area of research. The more that is understood about how and why depression occurs, the more likely it is that new treatments can be developed.
“Parents with depression should not feel guilty or worry excessively about the risk for their children to develop depression,” Dr. Mischoulon explains. “There are many factors that can influence whether someone will develop depression or not in their lifetime.”
