Loneliness and the psychosis continuum: a meta-analysis on positive psychotic experiences and a meta-analysis on negative psychotic experiences.

There is an increase in interest in the relationships between loneliness and psychosis. The notion of psychosis continuum implies that psychotic experiences extend from clinical populations with psychotic disorders to non-clinical populations. This meta-analytic review aimed to examine the respective associations of loneliness with positive and negative psychotic experiences along the psychosis continuum. A systematic database search was conducted and a total of 30 studies were included in the first meta-analysis and 15 studies were included in the second meta-analysis. There was a medium association between loneliness and positive psychotic experiences (r = 0.302, p < 0.001). In particular, the association between loneliness and paranoia was robust (r = 0.448, p < 0.001). The second meta-analysis revealed a medium association between loneliness and negative psychotic experiences (r = 0.347, p < 0.001). The associations between loneliness and both positive and negative psychotic experiences were found to be smaller among clinical than non-clinical samples. The above findings provided evidence for the associations between loneliness and the two core dimensions of psychotic experiences along the phenomenological continuum. Future research should examine the dynamics of these relationships in both clinical and non-clinical samples, preferably using a single-symptom approach.