Genetic Differences May Help Predict Suicide Risk in Depression

Depression is a common mental disorder that can affect people at different stages of life. A new study shows that genes play a greater role in depression that develops before the age of 25 than in depression that first appears after the age of 50.

This difference could have significant implications for how we identify, support, and treat the most vulnerable individuals in the future – particularly regarding suicide risk.
 

Large Nordic Data Set

By analyzing genetic data from over 150,000 individuals with depression – and an additional 360,000 without depression – from large Nordic biobanks, the researchers have shown that depression that begins before the age of 25 is genetically different from depression that develops later in life.

“This is an important step towards precision medicine in psychiatry, where treatment and prevention are increasingly tailored to the individual,” says Associate Professor of Biomedical Data Science John Shorter, who led the Danish part of the study.

Large Genetic Differences Between Early and Late Depression

Genes are only part of the explanation for depression—environment and life circumstances also play a major role, the researchers emphasize. But when focusing on the significance of genes, the results are striking:

The researchers identified 12 genomic regions specifically associated with depression that arises early in life, and 2 genomic regions associated with depression that appears later in life. The early forms of depression seem to have their roots in genes that are active during fetal brain development.

“What was particularly interesting was that the genes behind early depression are active already before birth – in the processes that shape brain development. This supports the idea that some individuals carry a greater vulnerability to mental disorders from birth,” says John Shorter.
 

Higher Risk of Suicide Attempts in Early Depression

Perhaps the most important discovery concerns what the genetic difference means in practice. The study shows that individuals with a genetic risk for early depression have a significantly higher risk of suicide attempts than those who develop depression later in life.

In specific analyses, the researchers found that the genetics that increase the risk of early depression are also closely linked to the risk of ending up in a life-threatening crisis. Among people with early-onset depression, those with high genetic risk were almost twice as likely to attempt suicide within 10 years (26% versus 12%).

The Path Toward More Personalized Treatment

“This suggests that genetic risk scores for depression could become a tool for assessing suicide risk. It also tells us that we cannot treat all depression the same way. Especially young people who are affected early may need special attention and close follow-up. We hope that this knowledge can help identify those who are at greatest risk – and perhaps even help save lives,” says John Shorter.

The study thus indicates that in the future, genetic information could be used as a tool to better tailor treatment and prevention of depression. It may also mean that doctors and psychologists should increasingly consider the age at which depression occurs when assessing what kind of help is needed.

Read the scientific article in the prestigious journal at Nature Genetics.