Epigenetic effects of stress being slowly uncovered

New research suggests that the impact of stress may be passed on from one generation to the next, and that psychiatric illness may have some degree of 'epigenetic heritability'.

Dr Isabelle Mansuy and her team from the University of Zurich in Switzerland discovered that male mice made depressed by early stress and lack of maternal care, appeared to pass this behaviour and anxiety on to their offspring.

The researchers believe that the male mice passed down epigenetic marks on crucial brain genes and on sperm cells. Epigenetics is involved in the regulation of gene activity, controlling which genes are switched on or off, and is achieved via a process of DNA methylation. In theory, before and after fertilisation all epigenetic marks are meant to be removed in the new embryo.

Previous studies, however, have hinted that this is not always the case, and that environmental factors can lead to methylation, which is not cleared and therefore seen in later generations. The researchers claim that their study offers strong evidence of this phenomenon, with Dr Mansuy claiming that 'This provides proof that the changes in DNA methylation are heritable'.

Dr Jonathan Mill from the Institute of Psychiatry in London, however, is more cautious about the implications of the findings. He told the New Scientist that 'more research is needed'. But that: 'It can provide a bridge between what's hard-wired in our DNA and what's modifiable through the environment'.

However, epigenetic marks on genes are reversible, which means that psychiatric illness is not necessarily predetermined and that research into the epigenetics of such conditions may lead to better treatment options in the future.

The findings published in the journal Biological Psychiatry in September were presented at the American Society for Human Genetics annual meeting in Washington DC last week.