Understanding Daily Depression, Drinking, and Marijuana Use among Homeless Youth using Short Message Service Surveying.

We used short message service surveying (SMS) with 150 homeless youth to examine the time ordering of feeling depressed with drinking alcohol, using marijuana, and using substances with friends. Multilevel binary logistic regression results revealed that youth who were depressed earlier in the day were more likely to drink alcohol later that day. Among depressed youth, heterosexual youth were less likely to drink alcohol than lesbian, gay, and bisexual (LGB) youth. Depressed youth had increased odds of using marijuana by a factor of 1.6, while heterosexual youth, compared to LGB youth, were 80% less likely to use marijuana. Females were 82% less likely and heterosexual youth 75% less likely to use substances with friends compared to males and LGB youth, respectively. These findings improve upon prior retrospective studies by using SMS to understand time ordering between feeling depressed and substance use in the same day.