Middle class heavy cannabis users are three times more likely to experience a downward shift in socioeconomic status compared to those who never used it, and four times less likely to experience an upward mobility — effects that are equivalent to those of heavy alcohol use. These striking findings come from a U.S. longitudinal study looking at the long-term financial and social impacts of cannabis exposure, published earlier this year in the journal Clinical Psychological Research.
The relative benefits and hazards of cannabis are at the center of several debates around the world that have been ignited by changes in public attitudes and knowledge about the drug. Opponents of cannabis legalization are concerned about the known and potential unknown risks associated with use, whereas defendants tend to highlight the promising therapeutic applications, the costs of criminalization, and the relative safety of the plant when compared to legal drugs such as alcohol.
Most experts agree that cannabis has a less pronounced socioeconomic effect than alcohol, but when researchers tried to quantify these impacts, they found a different picture. In 2005, a study reported that the two substances have comparable effects on delinquency, relationships, and education achievement. In 2007, another group concluded that heavy exclusive cannabis users had more social problems than did heavy exclusive alcohol users.
However, these studies share a couple of problems that undermine their conclusions. Because individuals were only tracked from their adolescence onwards, researchers might be missing the impact of earlier factors such as socioeconomic difficulties, childhood psychopathology, family organization, and educational predisposition, which could explain both cannabis use and the observed results. Other problems concern the precision of use measures, the role of onset age, the criminal status of cannabis, and the use of other substances.
The same issues are much less pronounced in the new study led by Dr. Magdalena Cerdá. The authors analyzed self-reported and registered data belonging to over 900 individuals born in New Zealand between 1972 and 1973, who have been tracked over the great part of their lives.
Individuals with a long history of regular cannabis use or dependence not only experienced worse social mobility, but also shared more financial, workplace, and personal relationship difficulties. These problems were linearly associated with the years of heavy use and covered debt issues, antisocial and unproductive behavior in the workplace, higher rates of relationship abuse and conflict, as well as an overall smaller satisfaction.
The observed trends remained significant after controlling for the confounders enumerated above, including the use of alcohol or other 'hard' substances (only a positive association between dependence and traffic-related conviction disappeared following the controls). When those with cannabis-related convictions (7% of the subjects) were removed, the socioeconomic effects of long-term cannabis exposure could still be seen, suggesting that the criminalization status of cannabis did not contribute much to these.
The total impact of cannabis dependence was comparable to that of alcohol dependence, except for financial difficulties, which were worse in the former (possibly due to a higher cost of acquisition). This data stands strongly against popular and expert opinions that cannabis poses smaller risks than alcohol use. On the other hand, it also contradicts the narrative that cannabis use is more hazardous than alcohol.
As the authors note, their findings say nothing about the physical and mental impacts of the two substances, and it remains to be seen whether their findings hold true in contexts where cannabis is legal or a larger percentage of the population consumes it. Regardless of the opinions held, they offer a much needed perspective for the ongoing debate on cannabis legalization.
- Featured image via Rafael Castillo.