Change in perceived risk associated with marijuana use in the United States from 2002 to 2012.

Context: The role of a dynamic legal, medical, and social setting in affecting the perceived risk associated with smoking marijuana has not been well studied. We sought to determine whether there has been a change in the perceived risk associated with marijuana use over time.

Methods: A cross-sectional study was conducted using the 2002-2012 National Survey on Drug Use and Health. Respondents were asked to classify the risk of smoking marijuana. Regression analysis and the Mann-Whitney U test were used to analyze the data.

Results: A total of 614579 respondents were identified. Between 2002 and 2012, the percent of respondents who characterized regular marijuana use as being associated with "great risk" decreased from 51.3% to 40.3%, while the percent of respondents who characterized it as being associated with "no risk" increased from 5.7% to 11.7%. The percent of respondents who characterized occasional use as "great risk" decreased from 38.2% to 30.7%, while the percent of respondents who characterized it as "no risk" increased from 10% to 16.3%. There was a significant negative temporal trend in the perceived risk for both occasional and regular use of marijuana from 2002 to 2012 after controlling for age and gender (p < 0.001 for both). Increasing age was significantly associated with increased perceived risk for both occasional and regular marijuana use (p < 0.001). Males have a significantly lower perceived risk for regular marijuana use as compared with females (p < 0.001). Individuals who used marijuana during the preceding month reported a lower risk perception in both regular and occasional use.

Conclusion: Between 2002 and 2012, there was a significant decrease in the perceived risk associated with occasional and regular marijuana use. Younger age, male gender, and past month use were also associated with decreased perceived risk.