Scientists have discovered alterations in the sperm cell DNA of adult men who had been abused as children.
'We can look at our study as one small piece in the huge overall puzzle of how intergeneration trauma works,' said study author Nicole Gladish, a PhD candidate at the University of British Columbia in Canada. 'It is certainly possible that epigenetic changes in sperm cells play a role in the physical and mental health of the next generation, but we don't know for sure.'
The study, carried out at the University of British Columbia and Harvard University in Cambridge, Massachusetts, looked at methylation patterns in sperm from 34 men, who were classed as having been exposed to childhood abuse or not.
DNA methylation is a common type of epigenetic tag. Epigenetics alter the packaging of nuclear information, altering the way genes are accessed and expressed. Methylation in particular is often described as having a 'dimming' effect, leading to the down-regulation of genes.
'When the sperm meets the egg, there is a massive amount of genetic reshuffling, and most of the methylation is at least temporarily erased,' Dr Andrea Roberts, lead author of the publication, noted. 'But finding a molecular signature in sperm brings us at least a step closer to determining whether child abuse might affect the health of the victim's offspring.'
The researchers also suggest that DNA methylation in sperm has the potential to be used as a biomarker as evidence of whether abuse had happened in a criminal justice case. Professor Michael Kobor, a medical geneticist at the University of British Columbia, and also a study author said: 'It's conceivable that the correlations we found between methylation and child abuse might provide a percentage probability that abuse had occurred.'
Environment-induced epigenetic changes have been shown to be passed on to offspring in animals. However, the impact of psychosocial stress on human sperm and eggs is not well understood.
Next the researchers plan to investigate whether these epigenetic changes would persist in the children of men who had experienced abuse. Larger-scale studies could help to find out whether the effect of childhood abuse could be passed on further down the generations.
The research was published in Translational Psychiatry.