WHY IT MATTERS: If you are a parent or caregiver, this research reinforces that community-wide prevention strategies matter just as much as individual conversations, because when overall teen cannabis use rises even modestly, the number of teens using heavily tends to rise proportionally. CLINICAL OVERVIEW: Research examining Swedish adolescents suggests that cannabis use at the population level follows predictable consumption patterns similar to those long observed with alcohol, where changes in average use correlate with changes in heavy use. This finding is clinically significant because it implies that public health strategies proven effective for alcohol, such as population-level prevention rather than solely targeting high-risk individuals, may also apply to adolescent cannabis use.