Predicting Changes in Marijuana Use Among Adults Who Are Parents: Implications for Marijuana Legislation

Following marijuana legalization, there has been increased public health concern that youth access to marijuana will increase, which will also increase marijuana use among youth. One important avenue for youth access is through parents who use marijuana. Yet little is known about marijuana use patterns among adults who are parents or how to best intervene with this population. The current analyses examines longitudinal pattern of marijuana use among parents as well as tests what factors influence change in marijuana use over time. Four mechanisms are examined: (a) child age, (b) previous use of marijuana in young adulthood, (c) partner’s use of marijuana, and (d) pro-marijuana attitudes.

Data were drawn from the Seattle Social Development Project (SSDP), a panel study of 808 individuals followed from ages 10-39, and The Intergenerational Project (TIP) a longitudinal study of intergenerational transmission of problem behavior that includes the SSDP participants and their children. TIP study includes 383 SSDP parents and their families (oldest biological child and, where appropriate, a second caregiver) interviewed between 1 and 7 times over 9 years. Only data from SSDP parents was included in the current analysis. Parents were aged 27 at Wave 1 (collected in 2002) and 36 at Wave 7 (collected in 2011). Hierarchical Linear Modeling (HLM) was used to model marijuana use over the 7 waves and test the time-fixed (a, b) and time-varying (c, d) predictors.

Results indicate that marijuana use among parents generally declined from ages 27-36, although this pattern was explained by demographic controls. Few of the hypothesized mechanisms explained the slope (change) of marijuana use, but several factors had effects on the intercept. Specifically, child age (a) had no effects on parent marijuana use; previous use of marijuana (b) was associated with higher intercept and lower slope; partner’s time-varying use (c) and having pro-marijuana attitudes (d)  predicted greater marijuana use among parents. The effect of pro-marijuana attitudes on use increased over time. Future results will add a comparison group of SSDP participants who are not parents.

Prevention efforts aimed at protecting children from marijuana exposure in the family should start before parenthood; early marijuana use is carried into parenthood, regardless of parent age at child birth. Further, intervention with marijuana-using parents should consider a family-wide approach since marijuana using partners played an important role in promoting parent marijuana use. Finally, public health approaches need to approach parents’ attitudes toward marijuana use as those both impact the level of use and become stronger predictors over time.