These people may also suffer more money problems and have more difficulties with both work and personal relationships than their non-marijuana-smoking peers, WebMD quoted the research as saying.
Some specific problems longtime heavy pot users experience include antisocial behaviors at work, such as stealing money or lying to get a job, and intimate partner violence, the study authors said.
The lead researcher, an associate professor in the department of emergency medicine at the University of California, Davis Magdalena Cerda also pointed out that the economic and social problems experienced by regular, persistent Indian hemp users are not due to other, pre-existing characteristics of the users.
Cerda said preventing regular marijuana use, and early treatment of people who are dependent on the drug, may reduce the burden that users pose to their families, communities and the social welfare system.
She emphasized the need to know that persistent heavy use of Indian hemp may have consequences for how well people do in life, how they perform and function at work and in relationships with others.
“We also found that both cannabis and alcohol dependence similarly predicted declines in social class, antisocial behavior in the workplace and relationship conflict,” Cerda said.
In terms of financial troubles, marijuana was worse than alcohol, she said.
“Participants who were dependent on cannabis experienced more financial difficulties than those who were dependent on alcohol. So, the idea that cannabis is somehow safer than alcohol was not supported in our study,” Cerda said.
For now, alcohol is a more common problem than marijuana, she said. However, as marijuana becomes legal in more places, “the economic and social burden posed by regular cannabis use could increase,” she suggested.
To trace the effect of marijuana over years of use, Cerda and her colleagues collected data on more than 1,000 children born in 1972-1973 in Dunedin, New Zealand. The study participants were followed for 40 years.
The researchers collected data on more than 900 of the participants who had at least three of five adult marijuana assessments from ages 18 through 38.
Among these individuals, 18 percent were marijuana-dependent at at least one evaluation, and 15 percent were regular pot smokers at at least one assessment. The results in terms of social class, and work and relationship problems were the same for heavy users and those who were marijuana-dependent, the findings showed.
The study was published online March 23 in the journal Clinical Psychological Science.
However, people campaigning for the use of Indian hemp, also known as marijuana, have said the study does not prove that heavy pot smoking actually causes economic and social woes, only that it may be associated with the problems.
Paul Armentano, deputy director of NORML, a group that advocates for the legalisation of marijuana, noted that the study only showed an association between pot smoking and the problems cited by the researchers, WebMd noted.
“It is likely that those facing social and economic adversity are more likely than those who are not to turn to the use of legal and illegal intoxicants as a coping mechanism,” Armentano said.
These same people are likely to turn to readily accessible intoxicants, such as alcohol and cannabis, he said. “But, in these instances, the association is a result of subjects’ response to social and economic adversity − the adversity is not a result of the cannabis use,” he added.
Also, a distinction needs to be made between marijuana use and abuse, Armentano added.
A system that allows for the legal use of marijuana but restricts and discourages its use among young people is the best way to reduce the risks of abuse, and “provides an environment whereby consumers can learn the skills and knowledge to readily delineate use from abuse,” he said.