Animal and human research suggests that adolescent exposure to cannabis carries a particularly high risk for a range of negative outcomes, including psychosis-related symptoms, cognitive impairment, and substance use problems1-5. Findings of heightened risk associated with adolescent cannabis use, coupled with research pointing to a role of the endocannabinoid system in regulating neurodevelopm...

Recent interest has focused on the association between cannabis use and risk of psychosis. In the largest unselected, population-based study on this topic to date, we examined cannabis use and prodromal symptoms of psychosis at age 15-16 years among 6330 adolescents. Those who had tried cannabis (n=352; 5.6% of the total sample) were more likely to present three or more prodromal symptoms even ...

ISSUE ADDRESSED Australians' use of cannabis has been increasing. Over a third of Australians (35.4%) have used cannabis at some time in their lives and 10.3% are recent users. Almost two-thirds of cannabis users combine cannabis with tobacco. The aim of this study was to understand the process of mulling - smoking tobacco and cannabis together - using a grounded theory approach. METHODS Twen...

BACKGROUND Structural magnetic resonance imaging techniques are powerful tools for examining the effects of drug use on the brain. The nicotine and cannabis literature has demonstrated differences between nicotine cigarette smokers and cannabis users compared to controls in brain structure; however, less is known about the effects of co-occurring cannabis and tobacco use. METHODS We used voxe...

Cannabis sativa is both an illegal drug and a legitimate crop. The differentiation of illegal drug Cannabis from non-drug forms of Cannabis is relevant in the context of the growth of fibre and seed oil varieties of Cannabis for commercial purposes. This differentiation is currently determined based on the levels of tetrahydrocannabinol (THC) in adult plants. DNA based methods have the potentia...

BACKGROUND Cannabis use is decreasing in England and Wales, while demand for cannabis treatment in addiction services continues to rise. This could be partly due to an increased availability of high-potency cannabis. METHOD Adults residing in the UK were questioned about their drug use, including three types of cannabis (high potency: skunk; low potency: other grass, resin). Cannabis types we...

BACKGROUND Resting-state functional connectivity is a noninvasive, neuroimaging method for assessing neural network function. Altered functional connectivity among regions of the default-mode network have been associated with both nicotine and cannabis use; however, less is known about co-occurring cannabis and tobacco use. METHODS We used posterior cingulate cortex (PCC) seed-based resting-s...

CONTEXT While there is a growing literature on the linkages between early subjective responses to nicotine and alcohol and later risks of nicotine or alcohol dependence, to date there has been no study of this issue in relation to cannabis. OBJECTIVE To examine the extent to which subjective responses to early (prior to the age of 16 years) cannabis use were associated with subsequent cannabi...

There has been considerable debate about the reasons for the association observed between cannabis use and psychosis in both clinical and general population samples. Among the hypotheses proposed to explain the association are the following: 1) common factors explain the co-occurrence; 2 cannabis causes psychosis that would not have occurred in the absence of cannabis use; 3) cannabis precipita...

Arseneault et al (2004) very accurately reviewed recent epidemiological data and concluded that cannabis use should now be considered as a component cause leading to psychosis. Yet at least two unanswered questions remain. How can cannabis lead to psychosis? Are some subjects specifically vulnerable to the psychotogenic effect of cannabis? Several studies, including the Dunedin study, have sugg...