Depression can be in the genes
The belief that depression can run in families is nothing new, despite scientists having struggled to find a DNA link to back up the theory. But now researchers have identified two gene variants that are associated with major depressive disorder (MDD). Also known as clinical depression, this is one of the most severe forms of the condition and affects up to ten per cent of people at some point in their lives.
The research could settle the debate over whether depression is hereditary or dictated by a person's environment, and researchers believe it could also help lead to new drugs being produced to help the disorder. The study was published in journal Nature and was a large multi-team effort between Professor Jonathan Flint of Oxford University, colleagues at the Virginia Commonwealth University in the USA and researchers throughout China.
They were able to identify two gene mutations behind the condition by analysing the complete DNA of over 10,500 Chinese women, around half of which had MDD. They then replicated the findings in another group of 3,231 Chinese women with recurrent MDD and 3,186 healthy individuals matched by nationality, age and sex. They found that one mutation is similar to a protein called SIRT, while the second gene is called LHPP. SIRT is thought to deal with ageing and is part of the production of tiny compartments called mitochondria inside almost every cell of the body that convert food into energy. The findings suggest that mitochondria is what could be linked to depression, however the condition is so complex that the researchers speculate that more gene mutations could still be waiting to be found that may reveal more about the genetic links.
"Of all complex human illnesses, major depressive disorder has arguably proved the trickiest to understand. Our ignorance about the condition is in marked contrast to its impact on people and public health, " said Professor Patrick Sullivan, a psychiatrist at North Carolina University. "The disease is common, costly and associated with high rates of morbidity and mortality. As such, it stands to reason that this research is exciting for those who study MDD. This first identification of replicable, significant genome-wide associations for MDD is exceptional."
He added that he is hopeful that this research will lead to clues in the future for further treatment.