Everyone can cite famous people from Vincent Van Gogh and Virginia Woolf to Tony Hancock and Robin Williams, who were exceptionally creative and experienced mental health problems. There are so many examples that it seems obvious that there must be a link between mental illness and creativity.

Surely research would support this common wisdom? Not exactly.

In fact there is remarkably little good data on the topic. In a review of 29 studies conducted before 1998, 15 found no link, nine did find a link and five found it was unclear. So hardly a straightforward connection. And some of these were simply case studies rather than rigorous attempts to establish whether there really is a causal link.