Conflicts and humanitarian crises have forced an unprecedented number of people to undertake dangerous journeys in search of safety. Over 40% of these people are children. The protection and health needs of displaced children are therefore of critical international concern.

If a signatory to the Refugee Convention (1951, 1967), ¹ states have a responsibility under international law to provide a haven for asylum seekers and refugees. However, because of the volume of people seeking asylum, and an increase in political pressure domestically, many states have attempted to gain control over the irregular arrival of people seeking asylum (i.e. without a valid visa) through implementing policies of ‘deterrence’. One such strategy is mandatory immigration detention. Despite evidence that immigration detention does not deter asylum seekers, globally, there are at least 330 000 children detained every year, ^{Reference Nowak2} and the impact of these practices on children is severe.

In the current issue of British Journal of Psychiatry, Priestly and colleagues present a synthesis of research examining the mental health effects of immigration detention on children. ^{Reference Priestly, Cherian, Paxton, Steel, Young and Gunasekera3} The findings are unequivocal: any form of immigration detention is associated with adverse impacts on children’s mental health, physical health and development. Despite heterogeneity in design, location, context and sample size across the 21 studies included in the review and meta-analysis, the harmful effects of immigration detention were consistently observed across several psychological conditions, as well as behavioural difficulties and disrupted development. Another insight from the review is that three key parameters exacerbate the impact of immigration detention – namely duration, level of containment and certainty over length of stay. Studies consistently found that indefinite, protracted detention in a closed facility was associated with accelerated psychological harm for children, replicating research conducted with adults. ^{Reference Specker, Liddell, Bryant, O’Donnell and Nickerson4} However, these aggregated findings also lay to rest the claim that there is a ‘good’ version of detention; even shorter periods of detention in a non-held facility of definite duration were found to be harmful for children. Children are protected by the United Nations Convention on the Rights of the Child, ⁵ which stipulates that any arrangements for a child’s care and protection must be undertaken within their best interests. This review has implications for states that implement a ‘last resort’ policy regarding placing children in immigration. The evidence is clear: no detention is in the best interests of the child.

The most measured condition was post-traumatic stress disorder (PTSD), with an estimated prevalence of 32%, with post-traumatic stress symptoms being observed in 17–95% of participants across studies included in the review. ^{Reference Priestly, Cherian, Paxton, Steel, Young and Gunasekera3} The focus on PTSD in refugee research is common, due to the multitude of traumatic experiences that commonly occur pre-migration and during displacement. However, PTSD as a diagnostic category may not adequately account for psychological symptoms experienced in the face of continuing trauma – that is, a trauma that does not end. For children in immigration detention, trauma is cumulative – adding to their pre-detention trauma experiences – and it is complex, chronic, continuous and collective. ^{Reference Allwood6} It follows that the psychological ramifications of detention may not be fully measured in existing studies focusing on PTSD. Moreover, other relevant conditions, including adjustment difficulties, attachment disorders and prolonged grief, have not been well measured to date and will require further study. Current research may therefore under-represent the true psychological impact of immigration detention on children.

A further limitation of the existing evidence base is that studies are cross-sectional. As such, little is known of the longer-term effects of detention exposure. Retrospective studies indicate that elevated mental health, developmental and nutritional challenges continue post detention for children. ^{Reference Tosif, Graham, Kiang, Laemmle-Ruff, Heenan and Smith7} Cohort studies from non-migrant populations reveal that exposure to adverse childhood experiences (ACEs) affects the lifecourse of individuals, increasing the risk for a range of mental health and physical health conditions in adulthood. ^{Reference Felitti, Anda, Nordenberg, Williamson, Spitz and Edwards8} Research has demonstrated that this is due to neurobiological adaptations, involving multiple body systems including brain structure and function, that assist the child to survive an adverse environment, but can have maladaptive consequences as adults. ^{Reference Sampson, Newkirk and Teicher9} Drawing from this parallel research, children exposed to immigration detention could be at heightened risk of long-term health and mental health problems.

Another factor is a lack of studies investigating the resilience of children in immigration detention. Refugee children are coping with excessive stress by relying on their strengths and promotive factors that protect their well-being. It may be difficult to apply these coping strategies in the restrictive, adverse and uncontrollable setting of the detention facility. Early interventions are critical for disadvantaged children, but evidence-based psychosocial programmes for displaced children are commonly implemented in schools or communities to build social capital and belonging. ^{Reference Fazel and Betancourt10} Children in immigration detention are therefore unlikely to access the most appropriate forms of health and mental health support to protect their well-being.

What is so troubling is that the practice of immigration detention continues to expand globally, when there are non-custodial solutions available that are far less harmful and more protective of children. A two-pronged approach to address this challenge at both the practice and policy level is needed. First, it is critical that children can access early preventative interventions that are trauma informed and evidence based. It is not just the role of mental health professionals to respond to the needs of detained or previously detained children, but also general health, education, legal, social and community service providers who need to be aware of the psychological legacies of immigration detention on children.

Second, evidence-based advocacy can change policy. In Australia, waves of concerted efforts from grassroots, humanitarian and professional organisations and individuals over the past two decades have resulted in reduced numbers of children in immigration detention overall. As such, there are currently fewer than five children in Australian-based immigration detention centres as of 31 December 2024; ¹¹ however, the number of children in Australian-funded offshore detention centres is unknown.

The advantages of enacting policies that protect displaced children in host countries are numerous. When supported outside immigration detention, displaced children are more likely to settle and to grow new roots, enabling them not only to survive but to thrive in their new home.