Changes in cannabis use according to socioeconomic status among Finnish adolescents from 2000 to 2015

Factors Associated with Initiating Cannabis Use After Legalization in Canada: A Cross-Sectional Study

Background: Cannabis use has increased since the Government of Canada legalized nonmedical use in October 2018. We investigated demographic factors associated with initiating cannabis use after legalization. Materials and Methods: We used data from the 2018 and 2019 National Cannabis Survey and constructed multivariable regression models. Respondents' data were weighted and bootstrapped. We report relative measures of association as adjusted odds ratios (ORs) and absolute measures of association as adjusted risk increases (RIs). Results: Among the 58,195 households surveyed, 28,566 provided complete data (49%) and our weighted analysis represented 27,904,258 Canadians aged ≥ 15 years. Approximately one in five Canadians endorsed use of cannabis (19.8%), predominantly for nonmedical (9.5%) or combined medical and nonmedical (5.8%) reasons. Those who initiated cannabis use in the past 3 months (1.9%) were more likely to be younger (25-34 years vs. ≥ 65 years; adjusted OR 1.7, 95% confidence interval [CI] 1.1-2.8; adjusted RI 1.1%, 95% CI 0.1-2.0%), endorse poor to fair versus good to excellent physical health (adjusted OR 2.0, 95% CI 1.3-3.1; adjusted RI 1.7%, 95% CI 0.3-3.1%), and reside outside of Quebec (adjusted OR 1.4, 95% CI 1.1-2.0; adjusted RI 0.1%, 95% CI 0.6-1.1%). The 1% of Canadians who endorsed initiating use of cannabis due to legalization were more likely to reside outside of Quebec (adjusted OR 1.9, 95% CI 1.1-3.2; adjusted RI 0.5%, 95% CI 0.2-0.9%). Conclusion: Canadians initiating cannabis use after nonmedical legalization were likely to be younger and endorse worse physical health, and half of those using cannabis reported therapeutic use. Stricter policies, lower social acceptance, and less availability of cannabis in Quebec appear to have curtailed initiation of use after legalization.

Cannabis Use and CKD: Epidemiological Associations and Mendelian Randomization

Rationale & Objective

The association between cannabis use and chronic kidney disease (CKD) is controversial. We aimed to assess association of CKD with cannabis use in a large cohort study and then assess causality using Mendelian randomization with a genome-wide association study (GWAS).

Study Design

Retrospective cohort study and genome-wide association study.

Setting & Participants

The retrospective study was conducted on the All of Us cohort (N=223,354). Genetic instruments for cannabis use disorder were identified from 3 GWAS: the Psychiatric Genomics Consortium Substance Use Disorders, iPSYCH, and deCODE (N=384,032). Association between genetic instruments and CKD was investigated in the CKDGen GWAS (N > 1.2 million).

Exposure

Cannabis consumption.

Outcomes

CKD outcomes included: cystatin-C and creatinine-based kidney function, proteinuria, and blood urea nitrogen.

Analytical Approach

We conducted association analyses to test for frequency of cannabis use and CKD. To evaluate causality, we performed a 2-sample Mendelian randomization.

Results

In the retrospective study, compared to former users, less than monthly (OR, 1.01; 95% CI, 0.87-1.18; P = 0.87) and monthly cannabis users (OR, 1.15; 95% CI, 0.86-1.52; P = 0.33) did not have higher CKD odds. Conversely, weekly (OR, 1.28; 95% CI, 1.01-1.60; P = 0.04) and daily use (OR, 1.25; 95% CI, 1.04-1.50; P = 0.02) was significantly associated with CKD, adjusted for multiple confounders. In Mendelian randomization, genetic liability to cannabis use disorder was not associated with increased odds for CKD (OR, 1.00; 95% CI, 0.99-1.01; P = 0.96). These results were robust across different Mendelian randomization techniques and multiple kidney traits.

Limitations

Likely underreporting of cannabis use. In Mendelian randomization, genetic instruments were identified in the GWAS that included individuals primarily of European ancestry.

Conclusions

Despite the epidemiological association between cannabis use and CKD, there was no evidence of a causal effect, indicating confounding in observational studies.

Low income and schizophrenia risk: a narrative review

Despite decades of research, the precise etiology of schizophrenia is not fully understood. Ample evidence indicates that the disorder derives from a complex interplay of genetic and environmental factors during vulnerable stages of brain maturation. Among the plethora of risk factors investigated, stress, pre- and perinatal insults, and cannabis use have been repeatedly highlighted as crucial environmental risk factors for schizophrenia. Compelling findings from population-based longitudinal studies suggest low income as an additional risk factor for future schizophrenia diagnosis, but underlying mechanisms remain unclear. In this narrative review, we 1) summarize the literature in support of a relationship between low (parental) income and schizophrenia risk, and 2) explore the mediating role of chronic stress, pre- and perinatal factors, and cannabis use as established risk factors for schizophrenia. Our review describes how low income facilitates the occurrence and severity of these established risk factors and thus contributes to schizophrenia liability. The broadest influence of low income was identified for stress, as low income was found to be associated with exposure to a multitude of severe psychological and physiological stressors. This narrative review adds to the growing literature reporting a close relationship between income and mental health.

Immigrants, refugees and cannabis use

Immigration typically occurs from low- to high-income countries and regions. Unfortunately, these wealthier areas also have higher rates of cannabis use (e.g. European Union and the US). This systematic review aimed to summarize available studies on cannabis use among immigrants, refugees, and asylum seekers. In addition, evidence on the association between immigration and cannabis use was reviewed. The rates of cannabis use were lower among immigrants than natives. The risk and protective factors to cannabis use were quite similar to those of the native populations. The population at greatest risk for cannabis use were refugees, males, singles, non-religious, those with lower educational level, living in urban areas, with friends that use cannabis and/or other drugs. Cannabis use tend to increase over generations, and acculturation seems to play a pivotal role. First generation migrants report equal or lower consumption of cannabis when compared with the majority population with a subsequent increase in following generations, with a clear association with acculturation factors. A higher cannabis use was found among migrants with lower cultural congruity as well as a higher level of culture assimilation. This use seems to be unrelated to alcohol or illicit drugs consumption, but possibly associated with tobacco smoking.