In schizophrenia serum level of neurotrophin-3 (NT-3) is increased only if depressive symptoms are present

Aim: Neurotrophin-3 (NT-3) is a neurotrophic factor responsible for promoting development, survival and function of neurons. NT-3 may be involved in the etiopathology of schizophrenia and mood disorders. However it must be cleared up if changes of NT-3 level are associated with schizophrenia itself or are secondary to certain symptoms (e.g. negative or depressive). The aim of this study was to examine whether the presence of negative or depressive symptoms affects peripheral NT-3 concentration in patients with schizophrenia.

Methods: Data for 69 Caucasian adult hospitalized patients with chronic paranoid schizophrenia was compared with 27 healthy subjects. Level of NT-3 was measured in blood serum using enzyme-linked immunosorbent assay. Clinical symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS) and Calgary Depression Scale for Schizophrenia (CDSS).

Results: Patients were stratified into three sub-groups: non-depressed with no dominating negative symptoms (DEP-/NEG-), non-depressed with dominating negative symptoms (DEP-/NEG+) and depressed with dominating negative symptoms (DEP+/NEG+). Mean NT-3 concentration was higher in the DEP+/NEG + sub-group (202.61 ± 258.76 pg/mL) compared with the DEP-/NEG+ (83.79 ± 215.75 pg/mL), DEP-/NEG- (83.79 ± 215.75 pg/mL) and control (36.47 ± 73.84 pg/mL) sub-groups (p = 0.016).

Conclusion: We found that in schizophrenia serum level of neurotrophin-3 (NT-3) is increased only if depressive symptoms are present. There was no difference in NT-3 level between schizophrenia patients and controls.