Those who have experienced higher numbers of adverse childhood experiences are more likely to develop patterns of persistent and regular cannabis use during adolescence, according to new research published in Lancet Public Health. The study underscores the importance of understanding the impact of early life experiences on cannabis use trajectories.
Adverse childhood experiences refer to a range of negative events or circumstances that children might face during their upbringing, such as physical abuse, sexual abuse, emotional abuse, emotional neglect, bullying, parental substance use or abuse, violence between parents, parental mental health problems or suicide, parental separation, or a parent convicted of a criminal offense.
The primary motivation for conducting this study was to better understand the potential link between ACEs and problematic patterns of cannabis use during adolescence. As cannabis use among adolescents has been associated with psychiatric disorders and the prevalence of cannabis use disorder is increasing in certain countries, it is considered a significant public health concern. With changing cannabis policies and increasing availability, identifying who is at risk of developing problematic cannabis use becomes crucial for effective interventions.
“I’m interested in the causes of behaviour, and specifically the underlying causes of drug use and mental health problems during adolescence,” said study author Lindsey Hines, a lecturer in health psychology at the University of Bath.
“ACEs are consistently identified as a precursor to addiction, but I couldn’t find any studies that had considered a wide range of adversities and which had the benefit of using data that had been collected from the same people from their childhood all the way into their 20s.
To conduct this study, Hines and her colleagues used data from 5,212 individuals from the Avon Longitudinal Study of Parents and Children (ALSPAC), which is a large UK population-based birth cohort. The researchers collected data through questionnaires completed by children, mothers, or other caregivers. Data on cannabis use were collected at multiple time points between ages 13 and 24, while data on ACEs were collected at various time points between birth and age 18.
Among the participants, 71.6% had experienced at least one ACE between ages 0 and 12. The most prevalent ACE was having a parent with mental health problems or a history of suicide attempts.
Through latent class analysis, the researchers identified five distinct trajectories of cannabis use: low or no cannabis use, later onset occasional use, early persisting occasional use, later onset regular use, and early persisting regular use. Participants who reported 4 or more ACEs were over three times more likely to be in the early persisting regular use group, twice as likely to be in the later onset regular use group, and more than twice as likely to be in the early persisting occasional use group compared to the low or no cannabis use group.
In other words, experiencing a higher number of difficult or negative events in childhood seems to increase the chances of developing specific patterns of cannabis use, including regular use from an early age or starting regular use later on.
The researchers also found that certain ACEs were associated with specific cannabis use patterns. For example, parental substance abuse was strongly associated with early persisting regular use, while parental separation, parental substance abuse, physical abuse, emotional abuse, and interpartner violence were linked to early persisting occasional use. Parental separation was associated with later onset regular use.
“Existing research suggests that those who use cannabis regularly (i.e. when people are using at least once a week, as opposed to now and again) and at younger ages are more likely to experience mental health problems,” Hines told PsyPost. “We found that those we experienced four or more adversities (like childhood abuse, being bullied, or having parents with mental health or substance use problems) in childhood were much more likely to be using cannabis regularly, and at early ages.”
“We also found that children whose parents had alcohol or substance use problems were more likely to go on to use cannabis regularly as teenagers. The most interesting thing about this is work is that the adversity experienced was in childhood, well before the age people started smoking cannabis; this indicates we could explore ways parents with young children can take action now to reduce risks of later substance use.”
The researchers controlled for a number of factors, including maternal or partner substance use during pregnancy, maternal or partner mental health, and financial difficulties. Other factors like biological sex, childhood socioeconomic position, and cannabis initiation polygenic scores were also taken into account. But the study, like all research, includes some caveats.
“Attrition within the study means those who were included in this nested study were more likely to be White, female, and more affluent than the population from which the participants were originally drawn from,” Hines explained. “We have been unable to control for all potential confounding factors due to data availability and, therefore, cannot rule out that at least part of the observed association is due to unmeasured confounding.”
The study, “Adverse childhood experiences and adolescent cannabis use trajectories: findings from a longitudinal UK birth cohort“, was authored by Lindsey A. Hines, Hannah J. Jones, Matthew Hickman, Michael Lynskey, Laura D. Howe, Stan Zammit, and Jon Heron.