'Theory of mind' is the ability to work out what other people are thinking. This is something that most of us - to a greater or lesser extent - do naturally but problems with theory of mind have been linked with autism (where lack of empathy for others is one of the most important symptoms) and schizophrenia. A review of 29 studies into the link between theory of mind and schizophrenia has found that there is a 'large and statistically significant' link between problems with people's theory of mind and their chances of developing the condition. Interestingly people who had recovered from schizophrenia still had problems in working out what other people were thinking suggesting that theory of mind difficulties contribute to schizophrenia rather than vice versa.
Sprong, Mirjam ... [et al] - Theory of mind in schizophrenia : meta-analysis British Journal of Psychiatry July 2007, 191, 5-13