Nicotine and Cannabis Co-Use are Associated with Higher Symptom Burden than Use of Either Drug Alone in Early Psychosis: Results from a Multisite Study

Co-use of cannabis and nicotine in early psychosis is linked to higher Modified Colorado Symptom Index (MCSI) total scores, with 16% of participants reporting both.

• Why it matters: Nicotine and cannabis are commonly used together, yet few multisite studies have tested how their co-use relates to symptom burden in early psychosis.
• What they did: In a cross-sectional EPI-NET cohort of 738 individuals (mean age 22 years, 62% male), mixed-effects models tested none, nicotine only, cannabis only, or both against MCSI, using site as a random factor.
• The result: Use showed significant effects on total MCSI (F = 6.69, p < .001), driven by greater symptoms for both users versus none, nicotine only, or cannabis only, and more frequent use was associated with higher total scores.

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