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

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. 2006; Csordas & Bernhard, 2013), this characteristic may have influenced the SNP efficacy. [...]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. 1997; Pienaar et al. 2014), 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.