After countless studies and surveys, experts have reached the consensus that depression is genetic, but the complete answer is not that simple. There are numerous causes and risk factors associated with a person developing a depressive disorder, and genes are only one element of influence. Depression symptoms are also affected by biological, situational, and environmental features.
The Genetic Impact of Depression: What the Research Says
Leaders in the field believe that genetics is 40-50% responsible for depression, meaning that other contributing factors have an equal impact on whether or not a person eventually develops the condition.1 It’s important to note that someone with a first-degree relative with depression is up to three times more likely to have depression than the general population.1,2
Because genetics aren’t the only cause or contributing factor for depression, they aren’t completely indicative of the condition. In fact, studies with identical twins (i.e., people who share 100% of the same genetic coding) show that one twin can have depression while the other doesn’t. However, it’s more likely for identical twins to both have depression than it is for non-identical twins (i.e., people who share 50% of the same genetic code).2
What Does It Mean for Something to Be Genetic or Hereditary?
When something is genetic, it implies that the characteristic is transferred from parent to child through the genes. In other words, it’s passed from the sperm and egg at conception. Hereditary features are set in stone, so to speak, and resistant to change.3
For example, eye color is an inherited trait given directly to the child from the parents. The child will receive genetic material from both biological parents. These genes will determine the color of the offspring’s eyes. There are no environmental or other factors that will change the color.3 Thus eye color is strictly genetic and there is no way to change it without changing the genes.
Health conditions can be genetic or inherited as well. For example, sickle cell disease is a collection of disorders inherited from one’s parents. Fragile X syndrome, which leads to intellectual disabilities, is passed directly from parents to children, too.3 With conditions that are fully genetic or hereditary, parents with specific genes can result in children with the condition.
Is There a “Depression Gene”?
People interested in the genetic link with depression have searched for a so-called “depression gene.” While there’s a precedent to support the idea of a single gene causing a disorder, depression is influenced by numerous pieces of genetic code.4
For example, these three diseases are triggered by a single gene:2
- Cystic fibrosis
- Types of muscular dystrophy
- Huntington’s disease
To study the possibility of a depression gene, researchers from the U.S. Department of Veterans Affairs, Yale University, and the University of California – San Diego studied the genes of millions of participants. They found many genetic variants that were correlated with depression, but there could be even more undiscovered genetic factors that contribute to depression.4
Non-Genetic Causes of Depression
Non-genetic causes of depression are as numerous as they are varied, but they tend to involve stressful life events, often leading to what’s called situational depression. Most mental health issues are discussed in terms of nature (genetics) and nurture (experiences), and depression seems to be a condition of both. Each accounts for roughly 50% of the influence on the disorder.
Non-genetic causes of depression include:1,5
- Physical, emotional, or sexual abuse (past or present)
- Death of a loved one
- Divorce or separation
- Relationship problems at home, work, or school
- Traumatic life events like car accidents or violence
- Loss of job and financial stressors
- Social isolation
- Life transitions with children growing or moving out of the home
Other common causes of depression include:1,5
- Substance abuse: Consuming alcohol and other drugs can disrupt the normal brain chemistry to induce a period of depression
- Certain medications or physical health conditions: People with some forms of cancer, thyroid issues, and chronic pain frequently report depressive symptoms
- Pregnancy: Peripartum depressive disorder occurs in people who are pregnant or who have recently given birth
There are so many non-genetic causes of depression because depression itself is not just one disorder. Rather, it is an entire category of mental health conditions with unique symptoms and triggers. Other pieces of one’s personality, temperament, and coping skills can be protective or predispositions to developing depression.
Will Everyone in My Family Develop Depression?
If you have depression and decide to have a family, not everyone in your family will necessarily develop depression. Family heredity is part of the puzzle that leads to emergence, but it is only one piece. As discussed, many non-genetic factors like stressful life events, substance use, and medical conditions can contribute to the development of depression.1
Do Family Members Develop the Same Type of Depression?
If family members develop genetic depression, it won’t necessarily be the same type. They could develop a completely different depressive or psychological disorder. When a person has a strong family connection to depression, they could actually develop a major mood disorder like bipolar disorder or an anxiety disorder.2 Too much variability exists to know exactly how their mental health will be affected.
Can Depression Be Cured?
Mental health professionals do not usually assert that depression can be cured. It’s an intricate condition that can be chronic, so clinicians usually aim to provide treatments that effectively reduce symptoms linked to depression and return the client to a state where the condition does not limit their daily functioning. When depression is mild and professional treatments are sought early, depression can be well-managed.
Psychotherapy and medication management are the primary sources of treatment for someone with depression. Some may opt for only therapy, only medication, or a combined approach.6 Depression treatments may not work instantly, though.
Antidepressant medications can take four to six weeks to begin producing wanted effects. Therapy for depression can start addressing faulty thinking patterns, poor relationships, negative coping skills, and problematic behaviors during the first session, but it may take weeks of practice for the results to present.6
Additional treatments like brain stimulation therapy and esketamine represent new and emerging options, especially for people with treatment-resistant depression. Healthy lifestyle changes like diet, exercise, and regular, restful sleep can also improve depressive symptoms.6
Do Genetics Influence Treatment Options?
Currently, tests are working to understand the influence of genetics on treatment for depression. It seems that people with certain genetic factors could respond better to different types of medication. Historically, there hasn’t been a reliable way to predict whether a specific medication will work apart from asking about family history of medication use, but pharmacogenetic testing offers a more scientific method.
Pharmacogenetics is a method of testing a person’s DNA to see how medication will impact them.7 After a few trials of antidepressants, if someone still hasn’t found success with symptom management, the prescriber may recommend pharmacogenetic testing to guide future treatments. These tests do not guarantee a successful response to medications, but can help guide you and your provider on options.
Outlook for People With Depression
The outlook for people with depression can be hopeful, especially when mild symptoms are addressed early with professional treatment. In these cases, symptoms can resolve within a few months and never reappear.5 The prognosis changes when depression is more severe and paired with compounding variables.
Compounding variables include:
- Ongoing abuse or neglect
- Dangerous situations or environments
- Active substance use
- Chronic physical health problems
- Problematic relationships
No one can change their genes, but if necessary, people can and should adjust their lifestyle and environment to improve their symptoms of depression.
Final Thoughts
It’s a fair question: “Is depression hereditary?” The answer is yes, but not entirely. Genetics are 40-50% responsible for depression, meaning that other contributing factors have an equal impact on whether or not someone eventually develops the condition. If you have depression, know that you’re not alone. Consider reaching out to a therapist through an online directory.
