How does a history of abuse leave its mark on the brain? A grim new study from PLoS ONE finds differences lurking in the brains of people who were abused as children and then committed suicide. The differences were epigenetic, meaning that rather than finding changes in the DNA sequence, there were differences in the frequency with which a chemical group, called a methyl group, is attached to certain regions of the DNA. This chemical modification can reduce expression of genes: in this case they looked at epigenetic changes to a gene that is critical for production of proteins and found that not only were there more methyl groups, but those methyl groups correlated with reduced gene expression. The implications are that abuse as a child may have led to these epigenetic changes which, in turn, could impact a critical function in the brain.
Reuters quotes Eric Nestler (University of Texas Southwestern Medical School in Dallas) as saying that drugs and psychotherapy might be able to reverse the epigenetic changes. Interestingly, the researchers found no correlation between these epigenetic changes and psychiatric diagnoses.
The researchers (Moshe Szyf of McGill University in Montreal and colleagues) compared 18 suicide victims with a history of childhood abuse to 12 patients who died from other causes. Overall, it strikes me as a complicated question to tackle, and one that might require more than a dozen samples to really pick apart. For example, New Scientist says that Szyf is now comparing his results with suicide victims who were not abused to determine whether the epigenetic changes were the result of abuse or suicide. Seems like an important control to do, and in fact it’s interesting how we’ve all homed in on the ‘child abuse’ angle when the paper stresses the ‘pathophysiology of suicide’ rather than abuse.
But it’s an interesting start, and follows on previous work in animals, including the fascinating study from several years back showing that mouse pups neglected by their mothers showed more stress later in life and harbored epigenetic changes in their brains.