biostudies-literatureUnknownBello DNIDA NIH HHSNIMH NIH HHSNIAAA NIH HHSCannabis and tobacco use are highly prevalent among people with psychosis and are associated with medical comorbidities and poor prognosis. Concurrent use of cannabis and tobacco ("co-use") is rising in the general population but has not been studied in psychosis. Given the devastating consequences of cannabis and tobacco use, it is critical to understand how their co-use affects psychiatric symptoms and the development of psychosis. We used the North American Prodrome Longitudinal Study 2, a multi-site prospective study of individuals at clinical high risk for psychosis (CHR) and healthy controls, to examine baseline differences in psychiatric symptoms and conversion to psychosis across substance groups: 1) CHR tobacco use, 2) CHR cannabis use, 3) CHR co-use, 4) CHR non-tobacco or cannabimedRxiv : the preprint server for health sciences2025.09.19.25336202https://www.ebi.ac.uk/biostudies/studies/S-EPMC12458528biostudies-literatureCannabis and Tobacco Co-Use Predicts Psychosis in Clinical High Risk Cohorts.PMC12458528U01 MH082022T32 AA013525U01 MH066069U01 MH066134U01 MH081928K23 DA059690P50 MH066286R01 MH116170R01 MH076989U01 MH081902U01 MH081988U01 MH081857U01 MH081944Mathalon DHAddington JBearden CEWalker EFBrady RORabin RAWard HBCarrion REPerkins DOBello DBlyth SHWoods SStone WSCadenhead KCornblatt BKeshavan MTsuang MTSeidman LCannon TDfalseCannabis and Tobacco Co-Use Predicts Psychosis in Clinical High Risk Cohorts.Cannabis and tobacco use are highly prevalent among people with psychosis and are associated with medical comorbidities and poor prognosis. Concurrent use of cannabis and tobacco ("co-use") is rising in the general population but has not been studied in psychosis. Given the devastating consequences of cannabis and tobacco use, it is critical to understand how their co-use affects psychiatric symptoms and the development of psychosis. We used the North American Prodrome Longitudinal Study 2, a multi-site prospective study of individuals at clinical high risk for psychosis (CHR) and healthy controls, to examine baseline differences in psychiatric symptoms and conversion to psychosis across substance groups: 1) CHR tobacco use, 2) CHR cannabis use, 3) CHR co-use, 4) CHR non-tobacco or cannabi2025-01-01T00:00:00Z2025 Sep2026-05-03T03:21:43.837Z2026-05-03T03:12:25.339ZS-EPMC124585284100147010.1101/2025.09.19.25336202