Cannabis use in SG often begins during adolescence, may progress to other drugs

Use of cannabis among Singaporeans usually starts during teenage years, primarily because of peer influence, reveals a study. Later in life, these users may progress to other illicit drugs such as heroin.

“This calls for early preventive and intervention efforts for helping at-risk adolescents build healthy social relationships,” said the researchers.

The study included 450 participants who had cannabis use at least once in their lifetime from the National Addictions Management Service, prisons, the Community Rehabilitation Centre, and halfway houses from August 2017 to May 2018. The researchers administered a face-to-face questionnaire and performed descriptive analyses.

Participants had a mean age of 40.9 years, and most of them (93.1 percent) were male. In general, the participants started using cannabis during adolescence, at a mean onset age of 16.5 years. Most of these users (89.6 percent) were introduced to cannabis by their peers. [Singapore Med J 2023;64:385-390]

This finding supported that in other countries such as Canada, Denmark, and the US. Specifically, in Ontario, Canada, patients under 20 years of age were 4.2 time more likely to report cannabis-related problems than those aged 20 years and above. [Prev Sci 2019;20:225-233; Eur Addict Res 2005;11:115-123; Soc Psychiatry Psychiatr Epidemiol 2004;39:97-105]

“The prevalence of cannabis use during adolescence may be attributable to adolescents’ misconceptions about the detrimental effects of cannabis use,” the researchers said. “Given the widespread use and easy availability in some countries, adolescents may think that cannabis is less harmful than other drugs, and thus, may be more open to experiment with it.”

Drug progression

Furthermore, nearly half of the participants (46.9 percent) had used cannabis before trying other illicit drugs. In addition, 42.1 percent of them had used heroin as the succeeding drug.

“The association between cannabis and heroin use may be explained by several factors,” the researchers said. “Besides the aforementioned psychosocial factors, there has been some neurobiological evidence from experimental animal studies.”

In other studies, cannabis and heroin have been shown to exert similar rewarding effects through a shared neuropathway: the mesolimbic pathway. This conduit is where dopamine is transmitted via the shared mu1 opioid receptor found in the ventral mesencephalic tegmentum. [Springer Science and Business Media 1999;187-205; Science 1997;276:2048-2050]

Previous studies have also reported the “gateway effect” of cannabis. For instance, when users of cannabis experience no serious detrimental effects, they tend to become more adventurous and eager to try harder drugs that have more harmful effects. [Behav Genet 2006;36:498-506; Addiction 2000;95:505-520]

In addition, using cannabis may expose these individuals to drug-taking cliques and deviant peer networks that provide easy access to illicit drugs, which can then increase their chances of progressing to harder drugs, according to the researchers.

The current study is limited by recall bias and the operationalization of drug progression.

“Future studies may aim to collect richer qualitative information to further assess the relationship between the use of cannabis and progression to other drugs,” the researchers said.