Acute paranoid schizophrenia relapsed inpatients present summer/ winter but not day/night changes in serum S100B concentrations

Abstract

Introduction. Healthy subjects present higher summer than winter S100B protein concentrations. There is no available information regarding if schizophrenia patients present the same pattern. The aim of this research is to study if patients with schizophrenia present seasonal changes in serum S100B concentrations.

Methods. In fifty-two Caucasian schizophrenia paranoid inpatients meeting DSM-IV criteria, serum S100B protein was measured at 12:00 h and 00:00 h the next day after admission. Patients were recruited for a period of nine months (July-March) and were grouped as summer, autumn or winter group according to the date of admission. Serum S100B levels were measured with an enzyme-linked immunoassay (ELISA) kit.

Results. Patients admitted in winter had significantly higher serum S100B concentrations at 12:00 h and 00:00 h than patients admitted in summer (12:00, winter: 287.5±264.9 vs. summer: 33.7±22.6, p < 0.05; 00:00, winter: 171.2±143.8 vs. summer: 23.3±18.6, p < 0.05). Autumn serum S100B concentrations were not significantly different from the summer or winter concentrations (12:00: 128.7±208.8, 00:00: 102.2±153.2). There were no significant differences between 12:00 and 00:00 serum S100B concentrations in any season.

Conclusions. Acutely relapsed paranoid schizophrenia inpatients present significantly higher serum S100B concentrations in winter than summer, the opposite pattern described in healthy subjects, both at midday and midnight. Controlling this seasonal change as source of bias in experimental designs is strongly advisable.