Complementarity in daily marijuana and alcohol among emerging adults.

Results add to the emerging conclusion of complementary marijuana and alcohol co-use within a single day, showing it occurs for both women and men, across a full range of marijuana use, and increases with time while being affected by alcohol use problems and day of week. The overall strong co-use relationship highlights risky behavior among late adolescents and supports an emphasis on common underlying substance use causes. However, the different pattern when assessed yearly demonstrates the importance of tailoring the timescale of analysis to the specific substance use question. (PsycInfo Database Record (c) 2021 APA, all rights reserved).