Most young people will not develop an addiction. But among those who use alcohol or drugs, some are far more vulnerable than others to developing patterns of use that become difficult to control.
Why that happens is rarely explained by one factor.
Research increasingly points to a combination of influences: the age at which substance use begins, childhood adversity, mental health, family history, peer groups, the substances involved and the developmental stage of the adolescent brain. None of these factors determines what will happen to an individual teenager. Together, however, they can alter the level of risk.
A 2024 review published in the European Journal of Public Health, drawing on 123 studies of adolescent alcohol and drug use, found that adverse childhood experiences, externalising disorders and substance use among peers or parents were among the factors consistently associated with greater risk. Earlier initiation and more frequent use during adolescence were also linked with later substance-use patterns.
It is a more complicated picture than the old idea that one drug, one bad decision or one rebellious period explains why addiction develops. Increasingly, the question is not simply whether a young person has used a substance, but what else is happening around that use.
Adolescence itself is part of the equation. The brain continues to undergo significant development into the mid-20s, particularly in systems involved in judgement, planning, impulse control and emotional regulation. At the same time, adolescence is a period marked by heightened sensitivity to reward, novelty and social influence.
That does not mean teenagers are incapable of rational decisions, nor that substance use during adolescence inevitably leads to addiction. It does mean that alcohol and drugs may be encountered at a time when important neurological systems are still developing.
The World Health Organisation says early onset of substance use is associated with a higher risk of dependence and other problems later in life. But even here, the relationship is not simple. Young people who begin using substances earlier may already differ from those who do not in ways that independently affect later risk, including family circumstances, behavioural difficulties, mental health and exposure to adversity.
Childhood trauma is one of the factors that appears repeatedly in the literature. Research has linked adverse childhood experiences and post-traumatic stress symptoms with earlier substance use and greater risk of later substance-use problems. That does not make trauma a prediction of addiction. Many young people who experience serious adversity never develop substance-use disorders. Rather, trauma can form part of a wider pattern of vulnerability, particularly when it sits alongside anxiety, depression, chronic stress or difficulties regulating emotion.
The same is true of family history and peer influence. A young person with friends who use substances frequently, or who grows up in an environment where drug or alcohol use is normalised, may face a different set of pressures and exposures from someone whose social environment is more protective. Again, the presence of risk does not make the outcome inevitable.
The substances themselves are also changing.
Cannabis has become an important area of research because products vary considerably in their concentration of tetrahydrocannabinol, or THC, the principal psychoactive compound in cannabis.
A UK longitudinal study published in Addiction in 2024 examined cannabis use reported at ages 16 and 18 and later psychotic experiences between the ages of 19 and 24. The researchers found that adolescents inferred to have used high-potency cannabis had more than twice the odds of reporting new psychotic experiences in early adulthood compared with those inferred to have used lower-potency cannabis.
The study did not prove that high-potency cannabis caused those experiences, and the researchers were clear about its limitations. Cannabis potency was reconstructed from participants’ later reports rather than measured at the time, and the study was observational.
Even so, it adds to growing interest in whether potency matters alongside frequency and age of first use.
Another 2024 study involving more than 6,600 adolescents aged 13 and 14 also found associations between high-potency cannabis use and probable mental-health disorders and auditory hallucinations. Again, the findings show an association, not a direct causal relationship.
The broader youth drug picture, meanwhile, is not one of simple escalation.
The long-running US Monitoring the Future survey found that reported use of most substances among adolescents remained at relatively low levels in 2024 after falling during the COVID-19 pandemic. More than 24,000 students across eighth, 10th and 12th grades took part.
Among 12th-grade students, 41.7 per cent reported alcohol use in the previous year, down from 45.7 per cent in 2023. Cannabis use fell from 29 per cent to 25.8 per cent, while 21 per cent reported nicotine vaping. Cannabis vaping was reported by 17.6 per cent.
Those figures are American and cannot be treated as a universal picture of teenage behaviour, but they underline an important point: youth substance use is changing rather than simply increasing.
Australia presents its own mixed picture.
Australian Institute of Health and Welfare data show that some forms of substance use among young people have declined over time, particularly daily tobacco smoking. At the same time, e-cigarette use has risen sharply among young adults. The proportion of Australians aged 18 to 24 who had ever used an e-cigarette rose from 19 per cent in 2016 to 49 per cent in 2022–23.
Drug and alcohol-related harm also remains significant. In 2024, people aged 15 to 24 recorded 1,203 alcohol and other drug-related ambulance attendances per 100,000 population, the highest rate of any age group in the jurisdictions included in the surveillance data. Alcohol was the most commonly recorded substance, followed by pharmaceuticals, cannabis and amphetamines.
These figures need context. They describe incidents serious enough to require ambulance care, not the proportion of young Australians living with addiction, and the national surveillance data are not complete across every jurisdiction.
What they do show is that serious drug and alcohol-related harm continues to affect young people even while some broader patterns of use are declining.
So why does one young person develop a problem while another does not?
The research increasingly suggests there is no single threshold. Risk accumulates differently.
One teenager may begin using substances unusually early, have a strong family history of addiction, experience instability or trauma, struggle with anxiety or behavioural difficulties and spend time with peers who use frequently. Another may encounter alcohol or cannabis occasionally but have fewer of those vulnerabilities, stronger support around them and no progression towards regular use.
Neither profile guarantees an outcome.
That is why researchers tend to talk in terms of risk rather than prediction.
It also changes what prevention looks like. A simple question about whether a young person has ever tried alcohol or drugs tells only part of the story. Frequency, age of first use, motivation and changes in behaviour can be far more revealing.
Has use become more regular? Is it being used to manage distress? Has school attendance or performance changed? Are relationships deteriorating? Is the young person becoming increasingly secretive? Did use begin particularly early?
Those questions move the discussion away from judgement and closer to what the research is actually showing.
New Orleans psychiatrist and addiction medicine specialist Dr Arwen Podesta, whose work includes youth addiction prevention, advocates a family-centred approach built around communication, education, accountability and clear expectations. Her emphasis reflects a broader shift in prevention towards identifying vulnerability before substance use becomes entrenched.
That may ultimately be the most important change in how teenage addiction is understood.
The distinction is no longer between the teenager who makes a “good” choice and the one who makes a “bad” one. The evidence points instead to a much more complicated interaction between biology, experience, environment and timing.
And that makes the question less about whether a young person has ever encountered drugs or alcohol, and more about what is happening around that use, how early it began and whether the pattern is starting to change.
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