Subclinical psychosis and depression: Co-occurring phenomena that do not predict each other over time

Background: The path from subclinical psychotic experiences to clinical disorder is thought to be mediated by the persistence of subclinical psychotic experiences. One of the factors that is likely associated with this persistence is depression. Although commonly viewed as interrelated concepts, the exact relationship between subclinical psychosis and depression is not clear. Methods: Cross-lagged path modeling was used to explore the relationship between subclinical psychosis and depression across and over time in an adolescent population seeking assistance for non-psychotic disorders (N = 138), measured at four occasions over a two-year period. Results: Subclinical psychosis and depression were related to each other at every cross-sectional measurement, but did not predict each other over time. Subclinical psychotic experiences and depressive symptom levels were highest at baseline, when participants presented to the clinical service for help. In addition, the relationship between them was also strongest at baseline and decreased significantly over time. Conclusion: The results suggest that psychosis and depression are interrelated phenomena that strongly co-occur in time, but longitudinally, one does not predict change in the other. Both psychopathological dimensions should be addressed when treatment is provided to adolescent help-seekers.