Correspondence between negative symptoms and potential sources of secondary negative symptoms over time

There has been a debate in the literature about the distinction between primary and secondary negative symptoms of schizophrenia. Our aim was to study the associations between negative symptoms and potential sources of secondary negative symptoms over time. A sample of 275 participants with at least mid-moderate negative symptoms was randomized into body psychotherapy or Pilates class in a previous study. No significant differences were found between groups over time and changes in the symptom domains were modest. The present investigation considers the longitudinal correlation between variables of interest at baseline, 3 and 9 months follow-up. Measures were the Clinical Assessment Interview for Negative Symptoms (CAINS), the Positive and Negative Symptom Scale (PANSS), the Calgary Depression Scale (CDSS) and the Simpson–Angus Extrapyramidal side-effects Scale (SAS). Mixed models were computed to test the longitudinal association between these variables. In a sensitivity analysis, the dosages of antipsychotic, illness duration and allocated intervention were taken into account. Overall, the course of extrapyramidal side-effects, depressive and positive symptoms was significantly related to the course of negative symptoms. Only extrapyramidal effects were longitudinally correlated to expressive negative symptoms. The sensitivity analyses showed unaltered results for positive symptoms and depression but a lack of association between extrapyramidal effects and the CAINS outcomes. In conclusion, the unambiguous interpretation between primary and secondary negative symptoms may lead to refined treatment approaches for schizophrenia and to increased effects of the interventions.