Investigation of serum BDNF levels in drug-naive patients with schizophrenia

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Abstract

The role of brain-derived neurotrophic factor (BDNF) is to promote and modulate the neuronal responses across neurotransmitter systems in the brain. Therefore, abnormal BDNF signaling may be associated with the pathophysiology of schizophrenia. Decreased BDNF levels in the brain and the serum of patients with psychotic disorders have been reported. In the present study, we assessed serum BDNF levels in a group of 14 drug-naive first-episode patients with schizophrenia (FEP), compared to 15 healthy controls. The serum BDNF levels in the sample of FEP patients was significantly reduced compared to normal controls (23.92 ± 5.99 ng/ml vs. 30.0 ± 8.43 ng/ml, F = 5.01, df = 1, p = .034). Negative correlations were shown between serum BDNF levels of the patients and the PANSS Positive and Negative subscale scores. Our findings indicate that BDNF levels at the onset of schizophrenia may reflect associated pathophysiological processes as well as the severity of positive and negative psychotic symptoms.

Introduction

The brain-derived neurotrophic factor (BDNF) is a member of the neurotrophic family that promotes the development, regeneration, sustaining and maintenance of neuron function in the central nervous system (Maisonpierre et al., 1990). BDNF modulates neurotransmitter synthesis, metabolism and neuronal activity (Altar et al., 1997) and is also involved in the development of dopaminergic-related systems (Hyman et al., 1991), and the mesolimbic dopamine systems (Shoval and Weizman, 2005, DeLisi, 1997). Abnormal BDNF signaling can influence neuronal differentiation and synaptic function leading to altered brain development and functioning. Neurodevelopmental abnormalities (Weinberger, 1987, Lawrie and Abukmeil, 1998, Mathalon et al., 2001, DeLisi, 1997) and a dysregulated dopamine system (Kapur, 2004) have been implicated in the pathophysiology of schizophrenia. Therefore, BDNF may be a marker of abnormal neurodevelopment and neurotransmission in schizophrenia.

Decreased serum BDNF levels have been reported in neuroleptic free patients with schizophrenia relative to healthy controls (Palomino et al., 2006, Buckley et al., 2007), and also in chronic patients with schizophrenia on antipsychotics (Grillo et al., 2007). Increased BDNF levels however have been reported in chronic medicated patients (Gama et al., 2007). BDNF levels have also been associated with the severity of psychotic symptoms of the patients (Palomino et al., 2006, Buckley et al., 2007).

Against the above background, we aimed to investigate a) whether serum BDNF levels in drug-naive, first-episode patients with schizophrenia (FEP) would be reduced compared to healthy controls and b) the correlation of serum BDNF levels with the positive and negative psychotic symptoms of the patients.

Section snippets

Subjects

Fourteen drug-naive (F/M: 4/10) FEP patients were recruited from the Psychiatric Department of the General Hospital of Nikea-Piraeaus Greece, from January 2006 through February 2007. Their mean age was 25.4 (SD ± 5.8) years. Blood samples were collected at the time of the patients' admission. Patients were assessed by SCID-IV (First et al., 1997) and by Positive and Negative Syndrome subscales (PANSS) (Kay et al., 1987). Exclusion criteria included a history of neurological disease and current

Results

Serum BDNF levels of FEP patients (23.9 [SD ± 5.99] ng/ml) were significantly reduced compared to healthy controls (30.0 [SD ± 8.43] ng/ml) (One-Way ANOVA F = 5.01, df = 1, p = .034, Fig. 1). The mean serum BDNF levels of male and female participants were not significantly different in both groups (male patients [n = 10]:23.06 [SD ± 5.9]ng/ml vs. females patients [n = 4]: 26.07 [SD ± 6.2] ng/ml, F = .70, df = 1, p = .41; male control participants [n = 6]:26.7 [SD ± 1.7], ng/ml vs. female control participants [n = 9]:32.2 [SD

Discussion

This study investigated serum BDNF levels and its associations with psychopathological variables in a sample of drug-naive FEP patients with schizophrenia. We found decreased serum BDNF levels in the patients compared to healthy controls. We also found significant negative correlations between serum BDNF levels of the patients and the PANSS Positive and Negative subscale scores.

The serum BDNF levels of patients with schizophrenia were significantly reduced compared to healthy volunteers. This

Conclusions

In conclusion, our findings showed decreased BDNF serum levels in a sample of drug-naive first psychotic episode patients with schizophrenia. This alteration may reflect pathophysiological processes related to the first psychotic episode of patients with schizophrenia. The correlations between serum BDNF levels and psychopathological state of the patients indicate that BDNF might reflect the formation and severity of positive and negative psychotic symptoms. More studies are needed to

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