Researchers led by Associate Professor Michael Poulter of the University of Western Ontario and Professor Hymie Anisman of Carleton University said they are the first to show proteins that modify DNA directly are more highly expressed in the brains of people who commit suicide.

The scientists compared the brains of people who committed suicide with those of a control group who died from heart attacks and other causes. They found the genome in depressed people who had committed suicide was chemically modified by a process normally involved in regulating the essential characteristics of all cells in the body.

The rate of modification in the suicide brains was found to be much greater than that of the control group.

"Interestingly, the nature of this chemical modification is long term and hard to reverse, and this fits with depression," he said. "The whole idea that the genome is so malleable in the brain is surprising. These observations open an entirely new avenue of research and potential therapeutic interventions."

The study appears in the journal Biological Psychiatry.