WHY IT MATTERS: Patients using cannabis to manage anxiety or depression should discuss this research with their physician, because the relationship between cannabis and mood disorders is complex enough that the same substance may help some individuals and worsen symptoms in others depending on factors like THC dose, frequency, and personal psychiatric history. CLINICAL OVERVIEW: Observational research continues to identify associations between cannabis use and elevated rates of anxiety and depression, though the directionality of these relationships remains a central challenge in interpreting the data. People with anxiety and depression are more likely to use cannabis, often as self-medication, which makes it difficult to determine whether cannabis is a cause, a consequence, or a coincidental co-occurrence in these populations.