Results showed that:
The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study
Findings: Between May 1, 2010, and April 1, 2015, we obtained data from 901 patients with first-episode psychosis across 11 sites and 1237 population controls from those same sites. Daily cannabis use was associated with increased odds of psychotic disorder compared with never users (adjusted odds ratio [OR] 3·2, 95% CI 2·2–4·1), increasing to nearly five-times increased odds for daily use of high-potency types of cannabis (4·8, 2·5–6·3). The PAFs calculated indicated that if high-potency cannabis were no longer available, 12·2% (95% CI 3·0–16·1) of cases of first-episode psychosis could be prevented across the 11 sites, rising to 30·3% (15·2–40·0) in London and 50·3% (27·4–66·0) in Amsterdam. The adjusted incident rates for psychotic disorder were positively correlated with the prevalence in controls across the 11 sites of use of high-potency cannabis (r = 0·7; p=0·0286) and daily use (r = 0·8; p=0·0109) (Lancet Journal)
Cannabis is harmful to the lungs, but in a different way to tobacco, causing significant respiratory symptoms such as bronchitis with evidence to suggest it can result in destructive lung disease – sometimes referred to as ‘bong lung’ – in heavy cannabis users.
These are the key findings from a review of research on the effects of smoking cannabis on the lungs undertaken by respiratory specialists, Professor Bob Hancox, from the University of Otago’s Department of Preventive and Social Medicine and Dr Kathryn Gracie, from Waikato Hospital’s Respiratory Department.
Cannabis is the second-most commonly smoked substance after tobacco and the most widely-used illicit drug world-wide. Although cannabis remains illegal in most countries, many countries – like New Zealand – are considering decriminalising or legalising its use.
Professor Hancox explains that much of the debate about legalising cannabis appears to revolve around the social and mental health effects. Both he and Dr Gracie believe policies around the liberalisation of cannabis should consider the wider health effects of smoking cannabis.
“The potential for adverse effects on respiratory health from smoking cannabis has had much less attention than the social and mental health effects,” Professor Hancox says.
“We believe policies around the liberalisation of cannabis should consider the potential impacts on the lungs.
Abstract - Objective: Alcohol and cannabis misuse are related to impaired cognition. When inferring causality, four nonexclusive theoretical models can account for this association: 1) a common underlying vulnerability model; 2) a neuroplasticity model in which impairment is concurrent with changes in substance use but temporary because of neuroplastic brain processes that restore function; 3) a neurotoxicity model of long-term impairment consequential to substance use; and 4) a developmental sensitivity hypothesis of age-specific effects. Using a developmentally sensitive design, the authors investigated relationships between year-to-year changes in substance use and cognitive development.
Conclusions: Beyond the role of cognition in vulnerability to substance use, the concurrent and lasting effects of adolescent cannabis use can be observed on important cognitive functions and appear to be more pronounced than those observed for alcohol.