The Consequences of Past and Current Parental Marijuana Use on Child Substance Use Onset: A Three-Generation Study

Overwhelming evidence links parental use of marijuana and other substances to use among their children. Past research has established parent-child transmission of both substance-specific tendencies to use (e.g., marijuana to marijuana) and a general tendency to use any substance (e.g., marijuana to alcohol or cigarettes). Most studies of the effects of parent substance use on child use, however, have focused on current parent substance use. Few studies have considered the possibility that parent substance use that occurred at earlier developmental stages (e.g., in adolescence or young adulthood) may also have implications for the healthy development of children. The proposed study will examine links between parent current marijuana use, parent marijuana use in adolescence and early adulthood, and substance use onset among their children.

Data will be drawn from two studies linking three generations, the Seattle Social Development Project (SSDP) and The SSDP Intergenerational Project (SSDP-TIP). SSDP began in 1985, and has followed a Washington State panel of 808 youth from ages 10-33. SSDP-TIP (N = 383 families) began in 2002, and includes those SSDP participants who are parents, their oldest biological child, and an additional caregiver, typically the SSDP parent’s spouse or partner. About 80% of TIP families continue to live in Washington. Seven waves of SSDP-TIP data have been collected, and participating children span ages 1 to 22 years. Analyses presented will focus on youth ages 6-18. Survival analysis will be conducted using SAS software, and analyses will reflect the accelerated longitudinal design of SSDP-TIP.

Results show that parent current marijuana use predicted onset of child alcohol and cigarette use, but not child marijuana use. Parent adolescent and early adult marijuana use was unrelated to child initiation of alcohol, cigarettes, or marijuana. Control variables included parent depressive symptoms in early adulthood, child gender, child birth cohort, and family current welfare receipt. Taken together with prior findings from TIP showing links between parent historical substance use and child social and cognitive functioning, results suggest that parent current substance use may be most closely linked to child substance use, whereas parent historical substance use may be more closely linked to child psychosocial functioning. Findings are discussed in light of the recent legalization of adult recreational marijuana use in Washington State.