BackgroundThis study tested the hypotheses that (i) the relationship between a history of childhood abuse and severity of psychosis is mediated by loneliness; (ii) the relationship between loneliness and psychosis is mediated by within-person fluctuations in depressive and anxious feelings. MethodsFifty-nine individuals with non-affective psychotic disorder rated the intensity of loneliness, positive symptoms, and depressive and anxious feelings during repeated moments in daily life (Experience Sampling Method). Childhood abuse was assessed retrospectively using the ‘Childhood Experience of Care and Abuse’ interview. To test the mediation hypotheses, a multilevel structural equation modeling paradigm was used. ResultsAs predicted, the relationship between severity of childhood abuse and positive symptoms was mediated by loneliness (b=0.08, 95% CI [0.02, 0.13], p=0.005). In turn, the relationship between loneliness and positive symptoms was mediated by within-person fluctuations in both depressive (b=0.04, 95% CI [0.02, 0.06], p<0.001) and anxious (b=0.02, 95% CI [0.01, 0.03], p=0.002) symptomatology. Depression was a stronger mediator than anxiety (b=0.02, 95% CI [0.00, 0.04], p=0.027). ConclusionsOur findings highlight the role of childhood abuse and loneliness in the severity of psychosis in daily life.