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CHILD abuse appears to leave chemical “caps” on victims’ genes that last into adulthood and which may help to trigger suicide.

Last year, and his colleagues at McGill University in Montreal, Canada, found that in people who had been abused and later committed suicide, more genes were “switched off” in brain tissue taken from the hippocampus – a region involved in mood control – compared with people who had not been abused and who had died in other ways.

To see if these differences might be linked to the abuse itself or to suicidal tendencies in general, the team has now compared samples of hippocampal tissue from 24 people who killed themselves – half of whom were abused or neglected as children, half of whom were not – and from 12 people who were not abused and who died in other ways.

The people who had both been abused and committed suicide had more chemical caps on their Nr3c1 gene, compared with the other groups. Nr3c1 is thought to help modulate the response to stress. They also had lower levels of the messenger RNA that corresponds to the expression of Nr3C1, indicating that the caps had suppressed the gene (Nature Neuroscience, ).

This suggests the changes in gene expression is linked to childhood abuse or neglect, and not to suicide. However, as people who were abused are more likely to kill themselves, Meaney suspects that the gene changes due to abuse may in turn predispose people to suicide.