Canadian scientists have studied how methylation patterns can affect suicidal behavior. Researchers at the University of Western Ontario, Carleton University, and the University of Ottawa looked at brain tissue from 20 people, 10 of whom had committed suicide, and found that the rate of methylation in the suicide brain tissue was almost 10 times that of the normal group. The research, published in Biological Psychiatry, suggests an epigenetic mechanism that could influence the "recurrent nature of major depressive disorder," they say in this BBC news story.