June 1 (UPI) -- A study by the University of Washington has found adults who smoke marijuana typically cut back when they become parents but do not necessarily quit completely.
More than half of Americans now support legalizing marijuana, according to a 2015 Pew Research Center report, and data from 2014 indicate a majority of Americans view alcohol as more damaging to a person's health than pot.
Researchers at the University of Washington's Social Development Research Group, or SDRG, found factors that influence marijuana smoking include the influence of a significant other, positive attitudes toward the drug and the onset of parenthood.
"When it comes to adults, we don't know long-term consequences of moderate marijuana use in the legal context, so that we cannot say that we absolutely must intervene," Marina Epstein, a UW research scientist, said in a press release. "However, when it comes to parents, their use is strongly related to their children's marijuana use, and that is a significant problem, since adolescent marijuana use can be harmful. Our study wanted to prepare us to build effective interventions for all adults if it becomes an issue."
Researchers surveyed 808 adults, parents and non-parents, who were first recruited for the study as fifth-graders at Seattle elementary schools in the 1980s as part of the long-term research study.
Participants were interviewed over a 12-year period ending in 2014 when most of the participants were 39 years old. A subset of 383 parent-only adults were surveyed ending in 2011, before the state voted to legalize marijuana.
The study showed a greater percentage of non-parents reported using marijuana in the past year compared to parents.
Nearly 40 percent of non-parents said they smoked marijuana in the previous year, compared to 25 percent of parents, at age 27. When participants reached their early 30s, marijuana use declined, with 16 percent of parents and 31 percent of non-parents reporting smoking marijuana in the previous year.
Participants who started using marijuana as young adults were significantly more likely to continue to use the drug into their mid-to-late 30s even when they became parents.
"This shows that we need to treat substance use as a family unit. It isn't enough that one person quits; intervention means working with both partners," Epstein said. "We also need to tackle people's positive attitudes toward marijuana if we want to reduce use."
The study was published in Prevention Science.