Is depression a genetic disorder?

Depression is a complex condition, and it can be influenced by several factors. These might range from negative life events or changes in your life, brain chemistry, your personality, or a variety of other environmental elements.

A commonly asked question revolves around the role of genetics: is depression something you can inherit? Does it run in families, and how likely are you to get depression if a family member develops it? Here, we delve into the relationship between depression and our genes, answering key questions and outlining key research in this area.

Is depression genetic?

The causes of depression have been the topic of lots of research. The current understanding of researchers in this field suggests that the answer isn’t completely clear-cut when it comes to the question of whether depression is genetic.

Some scientific studies suggest there's a genetic component to depression. For example, a study of 1.2 million people by Yale University identified 178 gene variants linked to major depression. It’s important here to note that these genetic variants don’t equal depression directly. Our genes carry information that determines our traits, and some of these genetic variants can make certain people more susceptible to developing depressive disorders.

Genes do have an impact, but environmental factors, personal experiences, and a range of other influences can also play a role. These can also differ from person to person. In some people, biological factors may be the most significant cause of their depression, with environmental factors offering less of an impact. In others, this might be the complete opposite.

Research is still ongoing, but the consensus today is that while our genes can make us more susceptible to depression, they are not the sole determinants. Life circumstances, coping mechanisms, and even other biological factors such as hormonal fluctuations, play integral roles in the complete picture of depression.

How can we research depression and genetics?

How do researchers look into the relationship between depression and genetics? One way is by looking at twins and family studies. Identical twins share 100% of their genes, and non-identical twins share 50% of their genes. As Stanford Medicine’s research outlines:

“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. Heritability is probably 40 to 50%, and might be higher for severe depression.”

From this, researchers suggest two things. One, is that cases of depression could be 50% genetic causes and 50% environmental or other causes. It might also mean that some cases of depression are entirely genetic, while others are solely caused by things that aren’t related to genes.

For instance, traumatic life events, prolonged stress, certain physical illnesses, and medications can act as triggers in people who are genetically vulnerable. These two areas interact with one another to affect the onset and course of depression.

Can you be born with depression?

If depression does have a genetic component, it naturally raises questions about whether you’re born with depression if you have the associated genes.

Firstly, it's important to note that no-one will be born showing the clinical symptoms of depression, as understood in adults or older children. The emotional range and cognitive understanding of babies and toddlers are vastly different from that of older people.

It's more likely that someone’s genes can predispose them towards depression. Some people might carry genetic markers or variations that increase their risk of developing depression at some stage in their life. This genetic vulnerability can pair with environmental factors or life experiences to further increase the risk of developing depression.

A child’s early years can also have a significant impact on the likelihood of developing depression. Babies, toddlers and children may be at increased risk of mental health issues like depression if they experience trauma, abuse or neglect during their early years.

It’s vital to emphasise here that if you've experienced depression and plan to have children, they won't be born with depression – nor will they be certain to develop it in later life. Genes are only one aspect of a complex condition. Similarly, if you have close relatives, such as parents or siblings, who have experienced depression, it doesn’t mean you’ll experience it yourself.   

Does depression run in families?

Research consistently indicates a genetic element to the development of depression. Family studies have illustrated that if a person has a close relative with depression, their risk of experiencing the condition is notably higher than someone without that family link. For example, this research from the American Journal of Psychiatry suggests that 40% of depression cases are due to a genetic link – with the other 60% made up of environmental factors.

However, it’s crucial to remember that family members not only share genes but also environments and experiences. Common factors such as upbringing, socio-economic conditions, exposure to traumatic events, and even learned coping mechanisms are believed to influence whether someone develops depression. In some families, challenging circumstances or patterns of negative thinking might be prevalent, contributing to the likelihood of multiple family members experiencing depression.

Gender is also thought to play a role – with one study in Sweden suggesting women have a 42% chance of hereditary depression compared to a 29% chance with men. Statistics on depression generally indicate that women have a higher prevalence of depression than men – although one factor contributing to this is that women are more likely than men to speak up about their struggles and get support for their mental health.

In many ways, it’s an issue of nature vs nurture. While genes (nature) might predispose a person to depression, the environment (nurture) plays a pivotal role in determining whether that predisposition evolves into actual lived experience of the condition.

What can I do if depression runs in my family?

Understanding that depression might be related to genes is vital for early intervention. If a family knows its history, they can be more proactive in seeking support, education and care. By fostering environments of understanding, open conversation, and positive coping strategies for depression, the impact of any genetic predisposition can be reduced.

If you have a close family member who has depression, and you’re worried about them and other members or your family, it’s vital to reach out for support.

Speak to your GP for an initial assessment of your situation and advice on potential next steps. If you or someone you love is struggling with depression, consider reaching out to Priory for private treatment for depression. Our multidisciplinary teams, working in purpose-built hospitals and wellbeing centres across the UK, deliver tailored treatments and support to help people overcome depression and live their lives to the fullest.