Is Depression Genetic And What Does That Mean?
Updated December 14, 2018
Reviewer Laura Angers
We've come a long way in our understanding of depression. We now know that it's something more than mere sadness. It's a disease which affects us emotionally, mentally and physically. The persistent low mood that we experience is a direct result of abnormalities in our brain chemistry.
But the causes of depression are less clear. We know that there is a genetic component to depression, but life events and upbringing seem to have an effect too. At the same time, not everyone with the same DNA or the same life events suffers from depression, either.
In reality, there is no one cause for depression. The disorder is caused by a complex interplay of factors and is different for each person. Examining the many possible causes of depression can help us empathize with others, as well as provide insight as to the most effective treatment for each person.
What The Statistics Say
The numbers have a lot to tell us about depression and genetics, but the message is mixed.
First of all, we know that 10% of people will suffer from depression at some time in their lives. The causes, however, are unclear.
We do know that if you have a direct relative (i.e., a parent or sibling) that suffers from depression, you are statistically almost three times as likely to develop the disorder yourself. At first glance, this would seem to indicate a strong genetic link. But don't forget that the experience of growing up in a home with a depressed parent or sibling can also have an impact on mental health.
When it comes to inheriting depression from a family member, women seem to be more susceptible than men, with a 42% chance of inheriting the illness, as opposed to only 29% of men. This is not surprising given the fact that women are statistically 1.7 times more likely to suffer from depression in general. This difference is usually attributed to hormonal factors.
Twin studies are a common way of determining the role of genetics in any illness. Through such studies, scientists have determined that there is a 40-50% heritability factor in depression. This means that about 50% of the cause of depression is related to non-genetic factors (environment, life events, etc.).
In fact, a 2011 study found that chromosome 3p25-26 is responsible for severe, recurrent depression running in families. But this does not explain the 50% heritability factor of mild to moderate depression.
What does this mean exactly? Again, we don't know.
It could be that half of all cases of mild or moderate depression are solely genetic, while the other half is not genetic at all. Or it could mean that each case of depression is caused by a 50/50 combo of genetic and environmental factors.
However, the numbers point to a slight difference in people who suffer from severe or recurrent depression. In these cases, the heritability factor is much greater. Close family members of those who suffer from this form of depression inherit it at a rate 4 or 5 times greater than the average person. But this type of depression is very rare, occurring in only about 3-5% of the general population.
Genetics And Disease
So what can we say about the link between depression and genetics based on these statistics? Not much. But we can find some clues about the causes of depression by looking at the links that genetics has with other diseases.
Some diseases are chromosomal. That means they are caused when sections of a chromosome are missing, duplicated, or altered in some way. Down's syndrome is an example of such a disorder. Based on recent research, you could argue that severe or recurrent depression may be considered a chromosomal abnormality as well.
Other diseases are known to be monogenic. That means they are caused by a defect or mutation in one specific gene which causes it to stop working correctly. Some examples of monogenic illnesses are cystic fibrosis and sickle-cell anemia.
But most diseases are multifactorial. These cannot be traced back to a single gene. They are caused by multiple gene mutations, in addition to environmental factors. These illnesses are the ones for which it is difficult to find a cause or even a treatment that works for everyone. They include cancer, diabetes, and cardiovascular disease.
Depression and most other forms of mental illness are multifactorial. That means there is no single depression gene. We don't know exactly which genes are responsible for depression, as it seems to be different for different people. And we're still not sure about the extent to which genetic factors interact with the environment and "nurture" to lead to depression.
Based on what we know about genetics and illness, it seems likely that each person inherits a set of genes from both parents which may predispose them to some illnesses, making it more likely that they will fall ill.
For example, one person might have a genetic predisposition to heart disease. This does not necessarily mean that he will suffer a cardiac event. However, if he embraces a lifestyle with unhealthy behaviors, this can trigger the predisposition that already exists.
It's the same with mental illness, too.
For example, let's say your mom or dad suffers from depression. You may be fine until your peers begin bullying and harassing you at school one day. This event, combined with a genetic predisposition, can lead to a depressive episode.
We know that depression is caused by a combination of genetic and environmental factors.
But what non-genetic factors are likely to trigger depression in someone who is genetically predisposed?
Statistically, the following events and circumstances have proven links to depressive episodes.
- Childhood abuse or neglect
- Grief and loss (especially losing a parent early in life)
- Financial problems
- Social isolation
- Health problems, especially those involving chronic pain
- Relationship problems and conflicts
If you consider these environmental factors carefully, you will see that they just make the question about depression and inheritability even more complicated.
For example, a depressed parent is more likely to engage in abusive or neglectful behaviors towards her children…making it difficult to tease out whether the child's depression is inherited or whether it's a result of abuse. Parents suffering from depression may also experience a lot of conflict with other family members, making the home environment a stressor. And perhaps most importantly, depressed parents may lack the skills or the motivation to teach their children positive coping strategies to deal with stress, making it more likely that these children will eventually develop depression as a result of inadequate coping strategies.
What This Means For You
Perhaps you suffer from depression, and you worry that your children might inherit that trait. Or maybe you have a parent who is depressed, and you wonder if that lingering sadness you feel might be the onset of a depressive episode.
Even with severe depression, there are steps you can take to prevent the onset of depression in you or a family member.
While you may be at greater risk, taking these steps can reduce that risk.
Educate Yourself About The Symptoms
Depression often starts as anxiety in young children. Be aware of signs of anxiety, such as nail biting or easy startling. If your child tends to worry obsessively, this can be a precursor to depression.
Also, pay attention if a family member abruptly loses interest in activities that he once enjoyed. Notice especially if he makes comments about not wanting to live anymore. This is a sign that your family member needs help immediately.
Learn Strategies To Manage Stress
Develop an array of coping strategies, such as meditation, breathing exercises, and affirmations. Agree on a procedure for peacefully resolving conflicts. Teach these coping strategies to other family members, and especially your children.
Connect With Others
Make sure that you and your family have a strong support network. Spend time with friends. Encourage your children to foster meaningful friendships. Sign up for sports or join a local church or synagogue. Connecting with a support network will improve your mental health.
Make sure everyone in the family has a daily exercise routine. Vigorous exercise releases feel-good endorphins in the brain which are a powerful antidote to depression.
Encourage Healthy Eating Habits
Consuming too much sugar can have an immediate negative impact on mood. A diet high in vegetables can give your brain the nutrients it needs to function at full capacity. A healthy diet is one of the simplest ways that you can make sure you and your family can enjoy optimum physical and mental health.
Avoid Drugs And Alcohol
You might think these substances will make you feel better. But in the long run, using drugs or alcohol just creates dependency issues. It also can make the home environment feel unstable and unpredictable to any children that live there.
Is depression genetic? The short answer is yes. But you are by no means doomed to struggle with poor mental health just because your parents did. You do have the power to break the cycle of genetic depression.
If you need help managing your depression, don't hesitate to reach out to one of the trained therapists at BetterHelp today.