Ancient DNA that remains in the brain is an indicator of psychiatric conditions.
Ancient DNA is an indicator of psychiatric disorders
A team at King's College London have found that thousands of DNA sequences that stem from ancient infections in the brain increase the risk of problems such as schizophrenia, bipolar disorder and depression.
Around eight per cent of DNA is made up of sequences known as Human Endogenous Retroviruses (HERVs), the products of viral infections from hundreds of thousands of years ago.
Boffins looked at information from large studies involving thousands of people and discovered that those with a specific set of HERVs were more susceptible to psychiatric disorders.
Dr. Timothy Powell, co-senior author of the study, said: "Our results suggest 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."