An investigation of cigarettes smoking behavior and nicotine dependence among Chinese methamphetamine users in two provinces

Co-administering cannabis with tobacco and persistent tobacco smoking after 4½ years in young adults who use stimulants: A prospective population-based study

Tobacco smoking remains highly prevalent in high-risk groups, including young adults who use cannabis and a variety of other drugs. We examine whether co-administering cannabis with tobacco is associated with heavier and more persistent tobacco smoking compared to separate use of these substances among young adults who use drugs recreationally. Data are from a prospective population-based study of young adults residing in Queensland, Australia, who recurrently used ecstasy or methamphetamine. The mean age was 20.8 years at baseline, and 47% were female. An ordinal regression model was developed (n = 277) with levels of tobacco smoking at 4½ years as the outcome. At baseline, just under half the sample (44.6%) had not co-administered cannabis with tobacco in the last month, 9.5% rarely co-administered, 7.7% sometimes co-administered, and 38.2% always co-administered. Always co-administering cannabis with tobacco was associated with more frequent and persistent tobacco smoking at 4½ years (Odds Ratio (OR): 1.98, 95% Confidence Interval (CI): 1.02, 3.83), independently of factors including baseline frequency of cannabis and tobacco use. Young adults who use cannabis should be advised not to co-administrate cannabis with tobacco, and comprise an important target group for tobacco smoking cessation interventions.

Methamphetamine (MA) Use Induces Specific Changes in LINE-1 Partial Methylation Patterns, Which Are Associated with MA-Induced Paranoia: a Multivariate and Neuronal Network Study

The use of psychoactive substances, including methamphetamine (MA) may cause changes in DNA methylation. The aim of this study was to examine the effects of MA use on long interspersed element-1 (LINE-1) methylation patterns in association with MA-induced paranoia. This study recruited 123 normal controls and 974 MA users, 302 with and 672 without MA-induced paranoia. The Semi-Structured Assessment for Drug Dependence and Alcoholism was used to assess demographic and substance use variables. Patterns of LINE-1 methylation were assessed in peripheral blood mononuclear cells and a combined bisulfite restriction analysis (COBRA) was used to estimate overall LINE-1 methylation (mC) while COBRA classified LINE-alleles into four patterns based on the methylation status of two CpG dinucleotides on each strand from 5' to 3', namely two methylated (mCmC) and two unmethylated (uCuC) CpGs and two types of partially methylated loci (mCuC that is 5'm with 3'u and uCmC that is 5'u with 3'm CpGs). MA users showed higher % mCuC and % mCuC + uCmC levels than controls. Use of solvents and opioids, but not cannabis and alcohol dependence, significantly lowered % uCmC levels, while current smoking significantly increased % uCuC levels. MA-induced paranoia was strongly associated with changes in LINE-1 partial methylation patterns (lowered % uCmC), heavy MA use, lower age at onset of MA use, and alcohol dependence. Women who took contraceptives showed significantly lower LINE-1 % mC and % mCmC and higher % uCuC levels than women without contraceptive use and men. The results show that MA-induced changes in LINE-1 partial methylation patterns are associated with MA-induced paranoia and could explain in part the pathophysiology of this type of psychosis. It is argued that MA-induced neuro-oxidative pathways may have altered LINE-1 partial methylation patterns, which in turn may regulate neuro-oxidative and immune pathways, which may increase risk to develop MA-induced paranoia.