Canadian researchers have found that childhood abuse victims who later commit suicide have marked genetic differences in their brains.

The researchers from McGill University in Montreal discovered the biological effects in a study of the brains of 18 men who committed suicide and who were also abused or neglected as children.

The results were compared to the so-called normal brains of 12 men who had died suddenly from other causes, and who were not abused as children - some of this group had various psychiatric problems such as anxiety disorders.

Although the genetic sequence was identical in the suicide and non-suicide brains, there were differences in their epigenetic marking - a chemical coating influenced by environmental factors.

Changes were found in the genetic material that makes make cells function in all 18 suicide victims.

Epigenetics is the study of changes in the function of genes that don’t involve changes in the sequences of DNA; the DNA is inherited from our parents, it remains fixed throughout life and is identical in every part of the body.

During gestation, however, the genes in our DNA are marked by a chemical coating called DNA methylation which is quite sensitive to its environment, especially early in life.

The epigenetic marks punctuate the DNA and program it to express the right genes at the appropriate time and place.

The researchers examined a set of genes that code for rRNA, a basic component of the machinery that creates protein in cells. Protein synthesis is critical for learning, memory and the building of new connections in the brain; it can affect decision-making and other behaviour. The scientists found that rRNA can be regulated epigenetically.

Lead researcher Professor Moshe Szyf says the changes involved the methylation process which turns genes on and off and the findings could help select people at high risk of suicide, and treat them to prevent future suicides.

The researchers say neglect and abuse can have biological effects which perpetuates unhealthy behaviours through the generations.

Professor Szyf from McGill’s Department of Pharmacology and Therapeutics, says it remains to be seen whether scientists can detect similar changes in blood DNA, which could lead to diagnostic tests - then whether interventions could erase these differences in epigenetic markings.

Experts say both drugs and psychotherapy may act to reverse some of these changes.

Previous research by the team in laboratory rats found that simple maternal behaviour during early childhood has a profound effect on genes and behaviour in ways that are sustained throughout life and parental abuse and neglect can affect the brains and behaviour of offspring.

The research is published in the Public Library of Science journal PLoS ONE.