Young people who use drugs but quit before adulthood are – on average – not harming their future life chances, according to new research which tracked thousands of people over a 16-year period.
Published in the peer-reviewed journal Addiction Research & Theory, the findings shed new light on the consequences of teen drug-taking. They demonstrate the importance of stopping drug use in early adulthood so that adult health and wellbeing are not compromised.
The results, based on data from more than 2,000 children in Australia, provide evidence that people who break their drug habit before age 30 do not have lower economic and relationship success, and life quality.
Now, the authors are calling on policymakers to address teen behavior issues such as school exclusion – which, the study shows, are linked with worse achievement later on. Treatment should target individuals whose use of drugs perisists beyond early adulthood, add the experts.
Adolescent behaviour problems predict drug use at 21 years, and drug use and life success at 30 years.
But teenage drug use or disorders don't appear to predict life success in adulthood among those who've ceased taking drugs before the age of 30.
What seems to best predict low life success outcomes is the persistence (over a longer course of time) of cannabis and amphetamine use.
Our findings linking problem behaviour and school problems in adolescence with drug use and life success represent an opportunity for policymakers to alter the young person's life trajectory."
Professor Jake Najman, University of Queensland, Australia
The study aim was to examine the extent cannabis and amphetamine use up to age 21 predicts life success at age 30. This is after taking into account a wide-range of prior life experiences and behavior.
The authors used data on 2,350 children born to mothers from in the Mater-University of Queensland Study of Pregnancy which began 40 years ago and has followed up participants at key life stages.
The children were tested at 14 years for IQ, mental health, aggression/delinquency. Information from mothers was also analyzed such as number of partners and child's contact with police.
Cannabis and amphetamine use was self-reported at specific age points (21 and 30). The authors also interviewed participants at age 21 about behaviors linked to past drug taking eg drug-related disorder.
Life success was measured at age 30 and defined according to three categories: socioeconomic, quality of life, and quality of intimate relationships.
The results show that more than one in five (22%) had ever had a cannabis use disorder and 4% problematic amphetamines use. Age of onset ranged from 15 to 19 and the participants reported high levels of drug use.
The proportion at age 21 who reported problematic drug was 19% for cannabis, a very small proportion (0.7%) for amphetamines, and 3% for those using both drugs. Of these, the issues persisted at age 30 for more than a third (36%) taking cannabis and 60% of those on cannabis and amphetamines.
A large majority of those who had ever met the criteria for problematic drug use were no longer using at clinically significant levels by age 21, according to the findings.
However, the use of cannabis at age 30 was strongly related to achievement. This was also dose-related – high use in adulthood associated with the highest rates of poor life success.
Given the very high rates of drug use by adolescents, the authors say more research is needed into interventions to prevent the persistence of drug use into adulthood which is strongly linked to lower life success.
Najman, J.M., et al. (2022) Do cannabis and amphetamine use in adolescence predict adult life success: a longitudinal study. Addiction Research & Theory. doi.org/10.1080/16066359.2022.2032679.