Effect of Cannabis Legalisation in Canada on the Incidence of Psychosis Consultations in Quebec City’s Psychiatric Emergency Services
21 February, 2024
A nationwide study in the United States observed no significant increase in psychosis diagnoses in states where cannabis was legalised. A study in Alberta and Ontario (Canada) observed such an increase but interrupted time series analyses suggested that this was not due to cannabis legalisation as it was the continuation of a trend antedating legalisation.
In Quebec, Canada, an observational study revealed a significant increase in cannabis use following legalisation but no significant difference in consultations for psychosis.
The present study observed no increase in the proportion of ED consultations for a psychotic episode in which evidence for cannabis consumption was obtained before and after legalisation, which is in line with previous studies stating that legalisation had no significative impact on ED’s consultations for psychosis.
Effects of acute cannabis inhalation on reaction time, decision-making, and memory using a tablet-based application
03 February, 2024
Consistent with prior research, study authors concluded that the occasional use group performed slower (reaction time task) or less accurately (memory task) from before to after smoking, as compared to daily use and no-use groups. This is consistent with daily cannabis use resulting in tolerance to the acute effects of cannabis. In the gap acceptance task, the daily use group took longer to complete the task after smoking cannabis, while at the same time increasing their success ratio.
“Taken together, the findings are consistent with acquired tolerance to certain acute ’drug’ effects. The increase in time that the daily use group required to complete the gap acceptance task may nonetheless indicate an acute effect of cannabis among those in the daily use group, who prioritised accuracy over response time. Psychomotor and cognitive assessment batteries, such as the one used in this study, hold promise for providing an objective measure of cannabis impairment”.
Brain Anatomical Alterations in Young Cannabis Users: Is it All Hype? A Meta-Analysis of Structural Neuroimaging Studies
06 February, 2023
Researchers found no detectable group differences in any of the global brain volumes (intracranium, total brain, total white matter and total grey matter) and regional brain volumes (i.e., hippocampus, amygdala, orbitofrontal cortex and total cerebellum). Age and cannabis use level did not predict (standardised mean) volume group differences. Contrary to evidence in adult samples (or in samples mixing adults and youth), previous single studies in young cannabis users and meta-analyses of brain function in young cannabis users, this early evidence suggests nonsignificant volume differences between young cannabis users and nonusers.
Neuroscience of Addiction and Mental Health Program, Healthy Brain and Mind Research Centre, School of Behavioural and Health Sciences, Faculty of Health Sciences, Australian Catholic University, Fitzroy, Victoria, Australia.
Age- and Sex-Related Cortical Grey Matter Volume Differences in Adolescent Cannabis Users: A Systematic Review and Meta-Analysis of Voxel-Based Morphometry Studies
01 December 2021
Findings suggest that grey matter volumes (GMV) differences between cannabis using and typically developing youth, if present, are subtle, and may vary as a function of age, cumulative cannabis exposure, and sex in young people. Whether age- and sex-related GMV differences are attributable to common predispositional factors, cannabis-induced neuroadaptive changes, or both warrant further investigation.
Johns Hopkins University School of Medicine, Baltimore, Maryland, United States.
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