Social isolation can be a precipitating factor for suicidal behavior. A large body of literature suggests that individuals who experience isolation in their lives are more vulnerable to suicide than those who have strong social ties with others. A study found social isolation to be among the most common risk factors identified by Australian men who attempt suicide. Professor Ian Hickie of the University of Sydney said that social isolation was perhaps the most important factor contributing to male suicide attempts. Hickie said there was a wealth of evidence that men had more restricted social networks than women, and that these networks were heavily work-based.