Is depression hereditary? The role of genes

Depression or major depressive disorder is a common illness that is difficult to decipher. It can have many different causes and symptoms, and its diagnosis and treatment are extremely complicated. Why do some people seem to be more prone to depression than others? Is it caused by an excess of stress or other environmental factors? Is depression hereditary? Let’s take a look at the role of genes in depression. Once we understand what causes this mental health problem, we can find ways to reduce potential risk factors. 

Does depression run in families?

Depression is a major contributor to global disease and a leading cause of disability worldwide. According to the World Health Organization, more than 264 million people are battling depression today. What’s more, depression can increase the risk of substance abuse, diabetes, and heart disease. In serious cases, it can also lead to suicide. 

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If you have a family member who has suffered from depression, you may have asked yourself the question: can depression be inherited? Am I at risk?
There is no clear-cut answer.

Depression heritability is a subject that has been extensively studied by researchers. Let’s take a look at the evidence.

Is depression hereditary? The depression gene

According to research, the depression gene can predetermine an individual’s susceptibility to this illness. 

In 2011, a British research group found a genetic cause for depression for the first time ever and published their findings in The American Journal of Psychiatry. (1) 

Is depression hereditary, according to this study? After analyzing a large sample of 971 sibling pairs affected by severe depression, the researchers found that a region on chromosome 3 called 3p25-26 can be linked to severe recurrent depression with genome-wide significance. Another, independent study published at the same time confirmed these findings. 

This game-changing discovery confirmed that a part of our DNA – which runs in families – may affect our susceptibility to depression. 

It’s important to note that the study only looked at patients with severe depression, so its results do not prove that the same gene is also responsible for less severe forms of depression. There may be other genetic factors involved that haven’t been identified yet. 

To what extent is depression hereditary?

Research shows that not everyone has the same likelihood of inheriting depression. 

According to studies conducted among twins, depression heritability ranges from 40% to 50%. (2) The rest is likely influenced by environmental and other factors. 

Interestingly, research has also found a difference between genders when it comes to hereditary depression. Women are 42% likely to inherit major depression, as opposed to men who only have a 29% risk, as per a study conducted among Swedish twins. (3)

Can depression be inherited?There is no clear-cut answer.

Environmental factors and depression

Genes are only partially responsible for depression: there are also environmental factors at play, some of which are just as closely related to family as genetics. 

Family life has an undeniable impact on our mental health. Children who grow up experiencing or witnessing conflict and abuse are more likely to develop mental illnesses like depression. 

Environmental factors that may contribute to depression include:

  • High levels of stress
  • Adverse childhood experiences
  • Traumatic events or major life changes (such as effects of divorce)
  • Chronic health issues 

But how environmental factors affect individuals so deeply that they become more vulnerable to depression? Not only is depression hereditary, but it can also be influenced by epigenetics. Let’s take a look at what this means. 

The epigenetics of depression

Researchers are attempting to bridge the gap between the genetic and environmental factors that cause depression through the study of epigenetics

Epigenetics investigates how external factors can switch genes on or off without causing alterations in the DNA sequence. 

Today, emerging technologies like artificial intelligence and machine learning are facilitating the study of epigenetics. As scientists make progress in this promising field, they may be able to find new modes of disease prevention and therapeutic treatment for depression. Further research is required before we can draw any conclusions.  

The link between serotonin and depression

For half a century, depression has also been linked to serotonin deficiency. However, in light of more recent research, this hypothesis does not seem to hold up.

Serotonin is a neurotransmitter with complex biological functions that regulates feelings of wellbeing and happiness, as well as anxiety. The hypothesis that lower levels of serotonin cause depression was born through clinical serendipity. The effects of certain antidepressant drugs led doctors to believe that changes in serotonin activity influenced changes in patients’ mood. 

However, a 2015 article published in the official journal of the World Psychiatric Association points to the fact that while impairing serotonin function can cause clinical depression in some circumstances, there is no evidence to suggest that it is necessary or sufficient. (4)

Low serotonin function has been shown to inhibit recovery from depression, but whether it lowers the mood of people at high risk of illness who have not experienced depressive episodes is much less apparent. 

How to reduce risk factors for depression

How to reduce risk factors for depression

Now that we have the answer to the question “Is depression hereditary?” and we have some clarity on the other potential causes of this disease, let’s look at how to reduce risk factors for depression.

Since depression often has its roots in things we cannot control – such as genetics and environmental factors – there’s no straightforward way to protect ourselves from it. 

However, there are things that you can do to help you cope with stress and bounce back more quickly from depressive episodes. 

1. Find ways to reduce stress

The best thing you can do to reduce your risks for depression is to start actively managing your stress levels. 

We experience stress when we’re overwhelmed and struggle to cope with our daily responsibilities. Everyone is affected by stress at some point in their lives. It’s a very common experience among adults: in fact, 8 out of 10 Americans report feeling stressed sometimes or frequently, as shown by GALLUP in its online article ‘Eight in 10 Americans Afflicted by Stress’. 

Sustained or chronic stress is a major risk factor for depression. But the good news is, you can keep stress at bay by adopting a few stress management practices. 

Things you can do to manage stress:

  • Identify situations that cause you to become stressed. Once you know what your triggers are, you’ll be better equipped to deal with them (or avoid them altogether). Keep a stress diary for a few weeks to pinpoint what is making you feel stressed and start developing your coping mechanisms.
  • Learn some time management tricks. Failing to prioritize your tasks and having an endless to-do list often leads to feeling overwhelmed. Learn how to manage your time and say no to additional responsibilities that would be stressful to commit to. 
  • Give meditation or other relaxation techniques a try. Doing exercises where you focus on your breathing, such as meditation or yoga, has been shown to reduce stress levels and help make you feel more balanced and in control. 
  • Reduce caffeine and alcohol consumption, both of which can worsen stress.
  • Make sure you get enough sleep – lack of rest can also cause stress.
  • Exercise daily. Physical activity releases hormones (dopamine, serotonin, and adrenaline) which make us feel better, thus helping to alleviate stress.

2. Take care of your health

Taking good care of your physical and mental health is key to preventing depression – whether depression runs in your family or not. Besides reducing alcohol consumption, making sure you get enough sleep and regularly engaging in physical exercise, you should also maintain a balanced and healthy diet

A 2017 study found that a healthy diet paired with nutritional counselling helped patients with moderate-to-severe depression improve their symptoms. (5)

No specific diet has been proven to prevent depression, but a healthy diet can contribute to improving your overall mood and decreasing your risks of developing depression. 

Healthy foods to include in your diet: 

  • Antioxidant-rich foods such as broccoli, spinach, blueberries, nuts and seeds, etc.
  • Complex carbohydrates such as whole grains
  • Protein-rich foods such as beans, lean meats and fish
  • Foods rich in vitamin B (specifically B-12 and B-9 or folate) such as eggs, poultry, fish, dark leafy vegetables, fruits, nuts and beans
  • Foods that contain Selenium such as whole grains, Brazil nuts and some seafood
  • Sources of Omega-3 fatty acids such as cold-water fish, flax seeds, chia seeds and walnuts

3. Build a support system 

If you feel like you might be experiencing mental health issues, it’s fundamentally important to have a reliable support system you can turn to.

Reach out to family and friends and talk to them about the problems you’re facing. Whether you’re experiencing stress or you just need someone to connect with, do not hesitate to communicate your feelings. This may help to elevate your mood and prevent you from feeling lonely or isolated.

If you suspect that you may be battling a severe condition like depression, whether you have a family history of hereditary depression or not, seek professional help immediately. Medical professionals or psychologists can give you advice on what steps to take in order to manage your illness.  

Conclusion: Is depression hereditary?

Currently, the scientific consensus is that depression is partly hereditary and partly influenced by environmental factors.

While the major causes of depression are out of our control, we can still attempt to reduce our risks by finding ways to manage our stress levels, taking care of our mental and physical health and building a reliable support system.

References

(1) Breen, G. & Webb, B. & Butler, A. & Oord, E. & Tozzi, F. & Craddock, N. & Gill, M. & Korszun, A. & Maier, W. & Middleton, L. & Mors, O. & Owen, M. & Cohen-Woods, S. & Perry, J. & Galwey, N. & Upmanyu, R. & Craig, I. & Lewis, C. & Ng, M. & Mcguffin, P. (2011). A Genome-Wide Significant Linkage for Severe Depression on Chromosome 3: The Depression Network Study. The American Journal of Psychiatry, 168(8), 840-847. https://doi.org/10.1176/appi.ajp.2011.10091342
(2) Lohoff, F. W. (2010). Overview of the Genetics of Major Depressive Disorder. Current Psychiatry Reports, 12(6), 539–546. https://doi.org/10.1007/s11920-010-0150-6
(3) Kendler, K.S. & Gatz, M. & Gardner, C.O. & Pendersen, N.L. (2006). A Swedish National Twin Study of Lifetime Major Depression. The American Journal of Psychiatry, 163(1), 109-114. https://doi.org/10.1176/appi.ajp.163.1.109
(4) Cowen, P. J., & Browning, M. (2015). What Has Serotonin to Do with Depression?. World Psychiatry: Official Journal of the World Psychiatric Association (WPA), 14(2), 158-160. https://doi.org/10.1002/wps.20229
(5) Jacka, F.N. & O’Neil, A. & Opie, R. et al. (2017). A Randomised Controlled Trial of Dietary Improvement for Adults with Major Depression (The ‘SMILES’ Trial). BMC Medicine 15, 23. https://doi.org/10.1186/s12916-017-0791-y