International research into Adverse Childhood Experiences (ACEs) suggests that children exposed to adversity have a higher probability of developing drug dependence later in life.

Of all the health outcomes studied in the largest review of childhood adversity, problematic drug use had one of the strongest links.

What are adverse childhood experiences?

Adverse childhood experiences, or ACEs, are potentially traumatic experiences before the age of 18. They include physical, emotional or sexual abuse, neglect, exposure to domestic violence, parental substance misuse, and growing up in a household affected by serious mental illness or imprisonment.

One proposed explanation for their long-term effects is prolonged stress during key stages of brain development. According to the US Centers for Disease Control and Prevention, repeated severe stress can affect how the systems that regulate emotion and respond to stress develop. That may increase vulnerability to mental health difficulties and harmful coping, including substance misuse.

What international research shows

A review published in The Lancet Public Health in 2017 pooled 37 studies covering 253,719 people. Those reporting four or more ACEs had higher odds of every health outcome studied than those reporting none. The link was strongest for problematic drug use and for violence, where the odds were more than seven times higher.

Higher odds are not the same as a sevenfold probability of addiction. The review measured relative odds, and its outcome was problematic drug use rather than only clinically diagnosed dependence.

Recent research on dependence

A systematic review published in 2026 looked specifically at substance-use disorders, including clinically defined addiction. It covered nine studies and more than 67,000 participants, although one cohort did not report its sample size. Across the studies measuring substance-use disorders, childhood adversity was consistently linked with higher odds, with adjusted odds ratios between 1.71 and 4.30. Differences between the studies meant they could not be combined into a single estimate.

So the evidence is not limited to experimenting with drugs. It also links childhood adversity with more serious substance-use problems and dependence.

More adversity, more risk, but no certainty

Research generally finds that risk builds up: people exposed to several forms of adversity tend to face greater risk than those exposed to one. The link is not automatic. Many people who experience childhood adversity never develop a substance-use disorder, and others develop one without significant childhood trauma. Genetics, social circumstances, peers, mental health and access to support all play a part. Stable relationships with supportive adults, safe surroundings and psychological help can reduce the long-term effects.

Evaluation

Mercieca's statement reflects a large body of international evidence. Studies consistently link adverse childhood experiences with a higher risk of substance misuse and dependence, particularly after several forms of adversity. He spoke of a higher probability, not of adversity inevitably causing addiction, which matches the evidence. Observational research cannot fully separate the effect of adversity from other factors, but the association is well established. The claim is rated True.