In a two-year longitudinal study from Brazil, cannabis use was associated with a 75% higher risk of loneliness, even after controlling for demographics, while physical activity and strong family relationships were protective.
People concerned about cannabis and social well-being, mental health researchers, loneliness intervention designers
RR 1.75 for loneliness
What the researchers found
Cannabis use was significantly associated with higher loneliness risk (RR 1.750, 95% CI 1.25-2.39, p<0.001) after adjusting for sociodemographic factors. Other risk factors included depressive symptoms (RR 1.214), anxiety (RR 1.191), and alcohol abuse (RR 1.579). Physical activity >150 min/week (RR 0.177) and good family relationships (RR 0.73) were protective.
Why it matters
Loneliness is recognized as a public health crisis with significant health consequences. Understanding modifiable risk factors, including substance use, could help develop prevention strategies.
The numbers in context
473 participants (87.1% female, ages 18-75). Cannabis RR: 1.750 (95% CI 1.25-2.39). Alcohol abuse RR: 1.579 (95% CI 1.32-1.88). Physical activity >150 min/week RR: 0.177 (95% CI 0.07-0.34). Good sleep quality RR: 0.483 (95% CI 0.39-0.59).
How the study worked
Two-year longitudinal study in Brazil using snowball sampling and online surveys (baseline May-June 2020). Multiple regression models adjusted for sociodemographic variables and weighted for attrition and sampling. Sample of 473 participants aged 18-75.
What this study cannot tell us
Snowball sampling with 87% female participants limits generalizability. Baseline collected during early COVID-19 pandemic may inflate loneliness and substance use. Cannot determine whether cannabis causes loneliness or vice versa. Self-reported measures.
How to read the evidence
Longitudinal design is stronger than cross-sectional, but snowball sampling, pandemic context, and predominantly female sample limit generalizability.
When this study was published
2024 study with baseline collected during COVID-19 (May-June 2020)
The bigger picture
Cannabis had the largest risk ratio among the clinical factors studied, even exceeding alcohol abuse. However, this was a Brazilian sample recruited during COVID-19, and the direction of causation is unclear. People who are lonely may be more likely to use cannabis.
Questions still open
- Does cannabis cause social withdrawal leading to loneliness, or do lonely people self-medicate with cannabis? Would these findings replicate outside the pandemic context?
Common questions
Was cannabis the biggest risk factor for loneliness?
What protected against loneliness?
Read the original research
Clinical and lifestyle predictors of loneliness: A two-year longitudinal study.
Journal of psychiatric research, 180, 482-488
Citation
Antonelli-Salgado, Thyago; Montezano, Bruno Braga; Roza, Thiago Henrique; Bouvier, Vitória; Zimerman, Aline; Noronha, Lucas Tavares; Marcon, Grasiela; Hoffmann, Maurício Scopel; Brunoni, André Russowsky; Passos, Ives Cavalcante. (2024). Clinical and lifestyle predictors of loneliness: A two-year longitudinal study.. Journal of psychiatric research, 180, 482-488. https://doi.org/10.1016/j.jpsychires.2024.11.025
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