Scientists have found that ancient viral DNA present in the body may be linked to psychiatric disorders in a discovery that could "revolutionise" mental health treatment.
Researchers at King's College London uncovered thousands of DNA sequences originating from ancient infections in the brain, with some increasing the risk of conditions like schizophrenia, bipolar disorder, and depression.
About eight per cent of the DNA is made up of sequences called Human Endogenous Retroviruses (HERVs) – products of ancient viral infections that occurred hundreds of thousands of years ago.
The team at King's looked at data from large studies involving tens of thousands of people, both with and without mental health conditions, as well as information from autopsy brain samples from 800 people.
They found that people with a specific set of HERVs were more susceptible to psychiatric disorders, including two that are associated with a risk for schizophrenia and one associated with a risk for both bipolar disorder and schizophrenia.
It was previously thought that these ancient viruses had no important function and were simply junk DNA.
Dr Douglas Nixon, co-senior author on the study and researcher at the Feinstein Institutes for Medical Research at Northwell Health, USA, said: “Further research is needed to understand the exact function of most HERVs, including those identified in our study.
“We think that a better understanding of these ancient viruses, and the known genes implicated in psychiatric disorders, have the potential to revolutionise mental health research and lead to novel ways to treat or diagnose these conditions.”
Dr Timothy Powell, co-senior author on the study and Senior Lecturer at the Institute of Psychiatry, Psychology and Neuroscience at King’s, said: “Our results suggest that these viral sequences probably play a more important role in the human brain than originally thought, with specific HERV expression profiles being associated with an increased susceptibility for some psychiatric disorders”.
Dr Rodrigo Duarte, first author and Research Fellow at the IoPPN, King’s College London, said: “We know that psychiatric disorders have a substantial genetic component, with many parts of the genome incrementally contributing to susceptibility.
“In our study, we were able to investigate parts of the genome corresponding to HERVs, which led to the identification of five sequences that are relevant to psychiatric disorders.
“Whilst it is not clear yet how these HERVs affect brain cells to confer this increase in risk, our findings suggest that their expression regulation is important for brain function.”
