Suicide victims who battled child abuse had clear genetic changes in their brains, a study by McGill University scientists has found.
During the study, researchers discovered what they say are key differences between the brains of ordinary people, and of those who took their own lives after suffering child abuse.
They found that the genetic sequence wasn't significantly different in the suicide and non-suicide brains, but there were differences in their epigenetic marking - a chemical coating influenced by environmental factors.
Researchers found that all of the 13 suicide victims in the study had experienced abuse as children.
"It's possible the changes in epigenetic markers were caused by the exposure to childhood abuse, although in humans it's difficult to establish causality between early childhood and epigenetic markers, in the way we have established this in animal subjects," said Moshe Szyf, a professor in McGill's Department of Pharmacology and Therapeutics.
"The big remaining questions are whether scientists could detect similar changes in blood DNA - which could lead to diagnostic tests - and whether we could design interventions to erase these differences in epigenetic markings," he added.
Szyf and his colleagues built on their world-renowned epigenetics work to uncover differences in the DNA in the brains of a group of male suicide victims from Quebec.
Epigenetics is the study of changes in the function of genes that don't involve changes in the sequences of DNA.
That sequence is inherited and remains fixed throughout life and is identical in every part of the body.
However, during gestation, the DNA acquired a chemical coating called methylation.
This is somewhat sensitive to one's environment, especially in childhood.
The epigenetic marks punctuate the DNA and program it to activate the appropriate genes at the right time and parts of the body.
The researchers focused on a set of genes that code for rRNA, a basic component of the machinery that creates protein, which in turn are critical for learning, memory and the building new connections in the brain; it can affect decision-making and other behaviour.
Researchers found that rRNA can be regulated epigenetically.
The brain samples in the latest study came from the Quebec Suicide Brain Bank, administered by Dr. Turecki of the Douglas Mental Health University Institute.
According to researchers, the study carried out on brain tissue can help develop intervention and prevention programs to help people suffering mental distress and who are at risk of committing suicide.
The study is set to be published in the May 6, 2008 edition of the online journal PLoS ONE.