Are people with genetic risk factors for mental disorders marked for life? Not according to a panel of experts who met in London last week to discuss the wider implications of genetic markers in mental illness.

Many psychological diseases, such as schizophrenia and bipolar disorder, are known to have a genetic aspect. This is illustrated by the fact that identical twins are more likely to share these illnesses than non-identical twins. The genetic influence varies depending on the disease, but is particularly strong in bipolar disorder, where, in 60% of cases where one identical twin has the disorder, the other suffers from it too.

But the panel scoffed at the concept that there could be a single gene "for" these illnesses, an idea that is commonly encountered in the mainstream press. This is because many mutations with a small effect are needed for a person to develop a psychological disorder.

Environmental factors are also important, including low socio-economic status, birth complications, childhood abuse and stress. However, not everyone who has been exposed to these risk factors develops a mental illness, showing that genes and environment must both contribute.

The experts emphasised the importance of further research into the link between genetics and psychological disorders to elucidate these interacting factors, and perhaps eventually develop more effective treatments. These will not necessarily be drugs, and could include environmental interventions, they added. However, the chair of the debate, Dr Arnand Saggar of the Royal Society of Medicine's medical genetics section, questioned whether these environmental factors would be easy to change.

Jigsaw pieces

"Molecular genetics is like the edge pieces of a jigsaw puzzle," said one panellist, Nick Craddock of Cardiff University. It will be up to researchers in other disciplines to fill in the rest of the puzzle, he added.

Prof Craddock, who also advises the BBC on its storylines on bipolar disorder, believes that research in this field will have an impact on psychological disorders in around 20 years. He likened the situation to cancer, which in the last couple of decades has gone from a death sentence to a treatable disease. "I think a similar thing can also happen in mental illness," he said.

He added that genetic discoveries could reduce the stigma attached to psychological disorders, by helping people to recognise that these are diseases just like heart failure, for example.

"What's exciting about genetic research it that it's a good opportunity to bring together elements that go towards creating mental health problems," said another panel member, Fenno Outen of the East London NHS Foundation Trust. "The nature and nurture camps got separated, but new research could help tie them together again. Mental health services have traditionally been the 'Cinderella services' – in other words, they've been forgotten."

He pointed out that there is currently little difference between developed and developing nations in mental health outcomes, despite a vast difference in resources. He also criticised the "imbalanced brain chemical" explanation of mental illness, which he described as "rather dumbed-down, although it has a basis in truth".

The third panellist, Prof Derek Bolton of King's College London's Institute of Psychiatry, emphasised the importance of moving from scientific findings to interventions, and cautioned that a strong causal link would need to be discovered. "I'm not convinced that [genetic research] is going to be helpful, but it's difficult to predict. I hope the government and public bear in mind the environmental and social factors."

Prof Craddock disagreed, arguing that the research would be "extremely helpful". "Genes are one important part of the jigsaw," he said.

Mr Outen conceded that "no treatments have come out of this yet. But we're still at the beginning." One audience member asked whether finding the cause of mental illness was an impossible task and he responded: "Maybe. But irrespective, we can find out a lot on the way."

The experts were speaking at the Progress Educational Trust event 'Marked for life: are genetic markers helpful in understanding psychological disorders?' The discussion took place at the Royal Society of Medicine on 3 March 2010.