1. ¹Department of Psychiatry, Friedrich-Schiller-University Jena, Jena, Germany
2. ²Department of Epileptology, University of Bonn, Bonn, Germany
3. ³Department of Psychiatry, University of Homburg/Saarland, Homburg/Saar, Germany

Correspondence: Dr S Smesny, Department of Psychiatry, Friedrich-Schiller-University Jena, Philosophenweg 3, D-07743 Jena, Germany. Tel: +49 3641 935297; Fax: +49 3641 935280; E-mail: stefan.smesny@med.uni-jena.de

Received 21 September 2006; Revised 5 December 2006; Accepted 28 December 2006; Published online 21 February 2007.

Abstract

Increasing evidence suggests modulating effects of cannabinoids on time of onset, severity, and outcome of schizophrenia. Efforts to discover the underlying pathomechanism have led to the assumption of gene environment interactions, including premorbid genetical vulnerability and worsening effects of continuing cannabis use. The objective of this cross-sectional study is to investigate the relationship between delta-9-tetrahydrocannabinol intake and niacin sensitivity in schizophrenia patients and healthy controls. Intensity of niacin skin flushing, indicating disturbed prostaglandin-mediated processes, was used as peripheral marker of lipid–arachidonic acid pathways and investigated in cannabis-consuming and nonconsuming schizophrenia patients and in healthy controls. Methylnicotinate was applied in three concentrations onto the forearm skin. Flush response was assessed in 3-min intervals over 15 min using optical reflection spectroscopy. In controls, skin flushing was significantly decreased in cannabis-consuming as compared to nonconsuming individuals. When comparing the nonconsuming subgroups, patients showed significantly decreased flush response. The populations as a whole (patients and controls) showed an inverse association between skin flushing and sum scores of Symptom Check List 90-R. Results demonstrate an impact of long-term cannabis use on lipid–arachidonic acid pathways. Considering pre-existing vulnerability of lipid metabolism in schizophrenia, observed effects of cannabis use support the notion of a gene environment interaction.