Study Finds Cannabis Use Not Related to Loss of Motivation

Study results show that marijuana use is not independently associated with a loss of motivation among teenagers, according to recently published research. The research, by a team of investigators affiliated with Florida International University, was published online last week by the Journal of the International Neuropsychological Society.

The authors of the study note that a reduction of motivation is commonly cited as a consequence of cannabis. However, previous research on the subject has largely been focused on adults and has yielded mixed results. 

To conduct the research, investigators recruited a group of 401 study subjects who were aged 14 to 17 years old at the onset of the research. Each subject completed a total of five biannual assessments throughout the study period.

The researchers assessed the motivation of the study participants through the use of two self-reported questionnaires including the Apathy Evaluation Scale and the Motivation and Engagement Scale, which consists of subscales that quantify disengagement, persistence, planning, self-efficacy and the value the study subjects place on school. The researchers also asked about the participants’ use of alcohol, marijuana and tobacco during each assessment, and performed an analysis of the data to model patterns of cannabis use and motivation over time.

The results of the two-year study show that cannabis use increased significantly, as did the planning facets of motivation and the lack of engagement. Greater cannabis use was associated with more disengagement, lower planning and less valuing of school.

However, when the data was controlled for variables including the subjects’ reported use of alcohol and tobacco and the effect of other factors such as age, sex and depression, the researchers found little evidence that cannabis use had an impact on motivation.

“Our findings do not support a relationship between cannabis use and reductions in motivation over time in a sample of adolescents at risk for escalation in cannabis use,” the authors of the study wrote in their conclusion, adding, “The current study contributes to the extant literature by examining these associations longitudinally in a large sample of adolescent cannabis users while controlling for important and often overlooked confounds, including sex and depression.”

Study Shows Increased Pot Use Does Not Cause a Loss of Motivation

The researchers also noted that the study failed to show a loss of motivation over time even though respondents reported a significant increase in cannabis use.

“Despite significant increases in levels of cannabis use in our sample, change in cannabis use did not predict changes in motivation, which suggests that cannabis use may not lead to reductions in motivation over time,” the authors of the study wrote.

But the data did indicate that cannabis use was associated with a lower perceived value of school, which concerned researchers because of the potential impact on the participants’ success in school and as adults.

“Future studies should continue to examine these associations longitudinally to determine whether heavier levels of cannabis use lead to reductions in motivation, and whether these reductions may be responsible for poorer educational and later life outcomes.”

Paul Armentano, the deputy director of the National Organization for the Reform of Marijuana Laws (NORML), said in a release from the cannabis reform advocacy group that the research serves to erode outdated stereotypes about cannabis.

“Modern science is setting the record straight and exposing much of the ‘reefer madness’ of the past decades,” Armentano said. “Unfortunately, many of these myths still remain prevalent in our society and are often raised by politicians in their efforts to justify the failed policies of marijuana prohibition and stigmatization. It is time for America to set aside these myths and adopt cannabis policies based on facts, not fears.”