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Letter to the Editor: Sodium nitroprusside for schizophrenia: could methodological variables account for the different results obtained?

Published online by Cambridge University Press:  09 December 2016

J. P. Maia-de-Oliveira
Affiliation:
University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil National Institute of Science and Technology in Translational Medicine (INCT-TM), Brazil Department of Clinical Medicine, Federal University of Rio Grande do Norte, Natal, RN, Brazil
G. B. Baker
Affiliation:
National Institute of Science and Technology in Translational Medicine (INCT-TM), Brazil Department of Psychiatry, Neurochemical Research Unit, University of Alberta, Edmonton, Canada
S. M. Dursun
Affiliation:
National Institute of Science and Technology in Translational Medicine (INCT-TM), Brazil Department of Psychiatry, Neurochemical Research Unit, University of Alberta, Edmonton, Canada
J. E. C. Hallak
Affiliation:
University of Sao Paulo (USP), Ribeirao Preto, SP, Brazil National Institute of Science and Technology in Translational Medicine (INCT-TM), Brazil
Corresponding
E-mail address:
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Abstract

Type
Correspondence
Copyright
Copyright © Cambridge University Press 2016 

We read with interest the paper by Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) about the effect of sodium nitroprusside (SNP) in patients with schizophrenia. It was a controlled trial where 20 subjects on antipsychotics received an infusion of SNP (0.5 µg/kg per min for 4 h) or placebo. The participants were assessed at baseline, immediately after the infusion, and 4 weeks later. No differences in outcomes were found between SNP and placebo (Stone et al. Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016).

Previously, we reported that SNP displays antipsychotic activity in animal models of schizophrenia (Bujas-Bobanovic et al. Reference Bujas-Bobanovic, Bird, Robertson and Dursun2000; Maia-de-Oliveira et al. Reference Maia-de-Oliveira, Lobão-Soares, Ramalho, Gavioli, Soares, Teixeira, Baker, Dursun and Hallak2015a ) and in schizophrenia patients taking antipsychotics (Hallak et al. Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013; Maia-de-Oliveira et al. Reference Maia-de-Oliveira, Belmonte-de-Abreu, Bressan, Cachoeira, Baker, Dursun and Hallak2014). We found that SNP improved some cognitive deficits in schizophrenia patients (Maia-de-Oliveira et al. Reference Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker, Dursun and Hallak2015 b) and long-term ketamine-induced memory deficits in rats (Kandratavicius et al. Reference Kandratavicius, Balista, Wolf, Abrao, Evora, Rodrigues, Chaves, Maia-de-Oliveira, Leite, Dursun, Baker, Guimaraes and Hallak2015). Trevlopoulou et al. (Reference Trevlopoulou, Touzlatzi and Pitsikas2016) reported that SNP attenuated ketamine-induced short-term recognition memory deficits and social isolation in rats.

Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) were not able to replicate our main findings. The authors argued that beneficial effects of SNP may occur in patients with a shorter history of illness, or with more acute exacerbation of symptoms. Hallak et al. (Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013) used the Bech's version of the Brief Psychiatric Rating Scale that rates from 0 to 4 (Bech et al. Reference Bech, Kastrup and Rafaelsen1986), while Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) used the Overall & Goram (Reference Overall and Goram1962) version, which rates from 1 to 7, suggesting that in the Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) study participants were less symptomatic. Indeed, Hallak et al. (Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013) worked with subjects with less than 5 years of disease and who were so severely ill they were hospitalized; symptoms were also recorded at baseline and at multiple times between infusion and 4 weeks.

Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) also seem to have worked with a population presenting other features that could potentially affect their final findings such as the presence of two schizo-affective disorder patients and seven subjects currently using cannabis; it was not clear if there was other illicit substance use. Furthermore, the majority of patients were current smokers (n = 12). Since it is well known that cigarette smoking induces a reduction in NO (Guo et al. Reference Guo, Oldham, Kleinman, Phalen and Kassab2006; Csordas & Bernhard, Reference Csordas and Bernhard2013), this characteristic may have influenced the SNP efficacy. Moreover, the majority of patients were black (n = 15, denoted as ‘black British and black other’). Since black Americans and black South Africans have been reported to present with attenuated SNP vascular effects (Stein et al. Reference Stein, Lang, Nelson, Brown and Wood1997; Pienaar et al. Reference Pienaar, Micklesfield, Gill, Shore, Gooding, Levitt and Lambert2014), perhaps the same happens concerning SNP's antipsychotic and cognitive effects; it may be inappropriate to compare these groups from three different countries, but it does raise the question of possible ethnic differences in responses to SNP.

In contrast to the Hallak et al. (Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013) study, Stone et al. (Reference Stone, Morrison, Koychev, Gao, Reilly, Kolanko, Mohammadinasab, Kapur and McGuire2016) found significant reduction of blood pressure and increase in heart rate during the SNP treatment. Could these cardiac alterations have negatively influenced the performance of the SNP group?

We believe that several variables could account for the different results reported, which points out the importance of avoiding possible confounding factors in future studies on this drug.

Declaration of Interest

All of the authors of this letter were also authors on the Hallak et al. (Reference Hallak, Maia-de-Oliveira, Abrao, Evora, Zuardi, Crippa, Belmonte-de-Abreu, Baker and Dursun2013) paper.

References

Bech, P, Kastrup, M, Rafaelsen, OJ (1986). Mini-compendium of rating scales for states of anxiety, depression, mania schizophrenia, with corresponding DSM-III syndromes. Acta Psychiatrica Scandinavica Supplementum 326, 137.Google ScholarPubMed
Bujas-Bobanovic, M, Bird, DC, Robertson, HA, Dursun, SM (2000). Blockade of phencyclidine-induced effects by a nitric oxide donor. British Journal of Pharmacology 130, 10051012.CrossRefGoogle ScholarPubMed
Csordas, A, Bernhard, D (2013). The biology behind the atherothrombotic effects of cigarette smoke. Nature Reviews Cardiology 10, 219230.CrossRefGoogle ScholarPubMed
Guo, X, Oldham, MJ, Kleinman, MT, Phalen, RF, Kassab, GS (2006). Effect of cigarette smoking on nitric oxide, structural, and mechanical properties of mouse arteries. American Journal of Physiology – Heart and Circulatory Physiology 291, 23542361.CrossRefGoogle ScholarPubMed
Hallak, JE, Maia-de-Oliveira, JP, Abrao, J, Evora, PR, Zuardi, AW, Crippa, JA, Belmonte-de-Abreu, P, Baker, GB, Dursun, SM (2013). Rapid improvement of acute schizophrenia symptoms after intravenous sodium nitroprusside: a randomized, double-blind, placebo-controlled trial. JAMA Psychiatry 70, 668676.CrossRefGoogle ScholarPubMed
Kandratavicius, L, Balista, PA, Wolf, DC, Abrao, J, Evora, PR, Rodrigues, AJ, Chaves, C, Maia-de-Oliveira, JP, Leite, JP, Dursun, SM, Baker, GB, Guimaraes, FS, Hallak, JE (2015). Effects of nitric oxide-related compounds in the acute ketamine animal model of schizophrenia. BMC Neuroscience 16, 9.CrossRefGoogle ScholarPubMed
Maia-de-Oliveira, JP, Abrao, J, Evora, PR, Zuardi, AW, Crippa, JA, Belmonte-de-Abreu, P, Baker, GB, Dursun, SM, Hallak, JE (2015 b). The effects of sodium nitroprusside treatment on cognitive deficits in schizophrenia: a pilot study. Journal of Clinical Psychopharmacology 35, 8385.CrossRefGoogle ScholarPubMed
Maia-de-Oliveira, JP, Belmonte-de-Abreu, P, Bressan, RA, Cachoeira, C, Baker, GB, Dursun, SM, Hallak, JE (2014). Sodium nitroprusside treatment of clozapine-refractory schizophrenia. Journal of Clinical Psychopharmacology 34, 761763.CrossRefGoogle ScholarPubMed
Maia-de-Oliveira, JP, Lobão-Soares, B, Ramalho, T, Gavioli, EC, Soares, VP, Teixeira, L, Baker, GB, Dursun, SM, Hallak, JE (2015 a). Nitroprusside single-dose prevents the psychosis-like behavior induced by ketamine in rats for up to one week. Schizophrenia Research 162, 211215.CrossRefGoogle ScholarPubMed
Overall, JE, Goram, DR (1962). The brief psychiatric rating scale. Psychological Reports 10, 799812.CrossRefGoogle Scholar
Pienaar, PR, Micklesfield, LK, Gill, JM, Shore, AC, Gooding, KM, Levitt, NS, Lambert, EV (2014). Ethnic differences in microvascular function in apparently healthy South African men and women. Experimental Physiology 99, 985994.CrossRefGoogle ScholarPubMed
Stein, CM, Lang, CC, Nelson, R, Brown, M, Wood, AJ (1997). Vasodilation in black Americans: attenuated nitric oxide-mediated responses. Clinical Pharmacology and Therapeutics 62, 436443.CrossRefGoogle ScholarPubMed
Stone, JM, Morrison, PD, Koychev, I, Gao, F, Reilly, TJ, Kolanko, M, Mohammadinasab, A, Kapur, S, McGuire, PK (2016). The effect of sodium nitroprusside on psychotic symptoms and spatial working memory in patients with schizophrenia: a randomized, double-blind, placebo-controlled trial. Psychological Medicine. Published online 22 September 2016. doi:10.1017/S0033291716002245.CrossRefGoogle ScholarPubMed
Trevlopoulou, A, Touzlatzi, N, Pitsikas, N (2016). The nitric oxide donor sodium nitroprusside attenuates recognition memory deficits and social withdrawal produced by the NMDA receptor antagonist ketamine and induces anxiolytic-like behaviour in rats. Psychopharmacology (Berlin) 233, 10451054.CrossRefGoogle ScholarPubMed

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