Abstract: Currently, the most important risk factor for hepatitis C virus (HCV) infection in Europe is intravenous drug use. To establish a better insight into the epidemiology of hepatitis C among intravenous drug users (IVDUs) in western European countries a systematic review on the prevalence of hepatitis C markers and their determinants was performed. Reports were identified by searches on Medline and on the internet and by screening reference lists of selected papers. The prevalence rates of anti-HCV in western European IVDUs reported in the 66 studies selected for analysis, ranged between 37 and 98%. No relation was found between prevalence rates and mean age, mean duration of intravenous drug use, geographical area, setting of the study, method of recruitment or the year(s) of collection of samples. Eleven studies concerning the prevalence of HCV-RNA in hepatitis C-infected IVDUs were selected for analysis. Prevalence rates ranged from 26 to 86%. Based on five studies, a statistically significant positive linear relation was found between the mean age of study population and the prevalence of HCV-RNA. Our analysis revealed considerable variation in prevalence rates of hepatitis C markers among IVDUs in western Europe. We found no conclusive explanation for this variability. Further research investigating the dynamics of the hepatitis C epidemic in IVDUs is necessary.

Abstract: Marijuana is the most widely used illicit drug, however its effects on cognitive functions underling safe driving remain mostly unexplored. Our goal was to evaluate the impact of cannabis on the driving ability of occasional smokers, by investigating changes in the brain network involved in a tracking task. The subject characteristics, the percentage of D9-Tetrahydrocannabinol in the joint, and the inhaled dose were in accordance with real-life conditions. Thirty-one male volunteers were enrolled in this study that includes clinical and toxicological aspects together with functional magnetic resonance imaging of the brain and measurements of psychomotor skills. The fMRI paradigm was based on a visuo-motor tracking task, alternating active tracking blocks with passive tracking viewing and rest condition. We show that cannabis smoking, even at low D9-Tetrahydrocannabinol blood concentrations, decreases psychomotor skills and alters the activity of the brain networks involved in cognition. The relative decrease of Blood Oxygen Level Dependent response (BOLD) after cannabis smoking in the anterior insula, dorsomedial thalamus, and striatum compared to placebo smoking suggests an alteration of the network involved in saliency detection. In addition, the decrease of BOLD response in the right superior parietal cortex and in the dorsolateral prefrontal cortex indicates the involvement of the Control Executive network known to operate once the saliencies are identified. Furthermore, cannabis increases activity in the rostral anterior cingulate cortex and ventromedial prefrontal cortices, suggesting an increase in self-oriented mental activity. Subjects are more attracted by intrapersonal stimuli (“self”) and fail to attend to task performance, leading to an insufficient allocation of task-orientedre sources and to sub-optimal performance. These effects correlate with the subjective feeling of confusion rather than with the blood level of D9-Tetrahydrocannabinol. These findings bolster the zero-tolerance policy adopted in several countries that prohibits the presence of any amount of drugs in blood while driving.