In response to a global rise in the number of people forcibly displaced because of war and persecution, many nations have adopted restrictive immigration policies to deter people from seeking asylum in their territories. In May 2024, the Rwanda Immigration Bill was passed in UK Parliament.¹ This legislation, which the newly elected Labour government has promised to repeal, seeks to remove certain² asylum seekers from the UK and relocate them to a third country (Rwanda). The UK Supreme Court and human rights agencies have raised serious concerns about the legal and humanitarian implications of offshore processing.¹ The psychiatric implications of these policies also merit consideration. Being removed to a third country by the government to whom one is applying for asylum may undermine one's sense of safety, agency, self-efficacy, certainty for the future and access to permanent resettlement pathways. This thus raises the question: does offshore processing place people seeking asylum at an increased risk for psychological disorders?

To our knowledge, no empirical research has specifically examined the psychological impact of offshore processing. This is likely because of two factors. First, asylum seekers are usually detained and processed onshore, within a country's domestic jurisdiction. Relocating people offshore, in a third country, is very rare. Second, independent scrutiny of offshore facilities is heavily restricted. For instance, in Australia, which has been operating offshore detention centres on Manus Island (Papua New Guinea) and Nauru^{Reference Karlsen3} since 2012, it was illegal for staff and medical professionals working in these facilities to disclose information about the conditions and impact of detentionFootnote ^a. This means that systematic research on the impact of offshore processing can only be conducted with detained people once they have been released.

Consequently, observations from the Refugee Adjustment Study^{Reference Nickerson, Byrow, O'Donnell, Mau, McMahon and Pajak4} – a multi-lingual survey of adult refugees and asylum seekers living in the Australian community between 2011 and 2018 – offers unique insight into the long-term psychological effects of offshore processing. In this cohort, 215 participants (21.7%) had experienced some form of detention before being released into the Australian community, while 775 participants (78.3%) had never been detained. This represents the largest available data-set of previously detained asylum seekers to our knowledge. As Australia operates both onshore and offshore detention, the majority of previously detained participants had experienced a combination of both detention typesFootnote ^b (73.3% combined offshore/onshore v. 26.7% onshore only) and the majority had been detained for 6 months or longer (55.5% 6 months or longer v. 44.5% detained for less than 6 months). This cohort, which averaged 38 years old and was 54% male, had been living in the Australian community for an average of 2 years when they completed the online survey.

Insights from this cohort revealed that while detention (in any form) was associated with an increased likelihood of psychological disorders, offshore detention and protracted onshore detention conferred a significantly higher risk of psychiatric illness. Findings revealed three distinct patterns. First, people who had previously been detained in any form of immigration detention were significantly more likely to exhibit a probable post-traumatic stress disorder (PTSD) diagnosis (odds ratioFootnote ^c 2.16, 95%CI 1.29–3.63), a probable depression diagnosis (odds ratio 2.57, 95%CI 1.60–4.11) and suicidal ideation (odds ratio 1.74, 95%CI 1.10–2.82) compared to refugees and asylum seekers who had never experienced detention. Second, offshore detention, for any length of time, was associated with a greater likelihood of probable PTSD (odds ratio 2.71, 95%CI 1.24–5.91) and depression (odds ratio 2.42, 95%CI 1.21–4.85) compared to onshore detention. Third, an interaction between detention type (offshore versus onshore) and length (shorter versus longer) emerged. Specifically, compared to those who had been detained in an onshore facility for less than 6 months, people who experienced longer onshore detention or offshore detention for any length of time were between 16.5 (odds ratio, 95%CI 2.8–98.8) and 20.2 (odds ratio, 95%CI 3.5–117.7) times more likely to have probable PTSD. Probable depression was five times more likely (odds ratio, 95%CI 1.7–15.1) and suicidal ideation was between 4.6 (odds ratio, 95%CI 1.5–14.3) and 5.5 (odds ratio, 95%CI 1.5–19.5) times more likely for these groups.

Findings from this analysis not only verify the established evidence-base on the adverse psychological effects of onshore detention,^{Reference Verhülsdonk, Shahab and Molendijk5,Reference Hedrick, Armstrong, Coffey and Borschmann6} particularly protracted onshore detention,^{Reference Steel, Silove, Brooks, Momartin, Alzuhairi and Susljik7} but they also demonstrate that these negative effects are even greater for offshore detention. These effects were large, even though this data-set was unable to include especially vulnerable groups of asylum seekers, such as people who remained in offshore detention for longer periods, were returned to their country of origin or died in these centres, reportedly from medical neglect, suicide or violent acts.⁸ This highlights an urgent need to consider the psychiatric consequences of policies that seek to detain, remove or transfer people who are fleeing violence and persecution. Detaining people in offshore detention facilities, in particular, may be especially harmful because of the way in which these facilities inadvertently resemble and replicate traumatic experiences. Australia's offshore detention centres have been run as forensic facilities, with confinement and limited access to appropriate medical care and psychological support.⁹ The living conditions within these sites have been described as extremely poor and unsafe, with reports of substandard sanitation, overcrowding, violence, neglect and child protection concerns.⁹ The potentially traumatic nature of offshore detention may account for why we saw that being detained offshore was linked to an especially pronounced likelihood of probable PTSD.

Given a growing interest in offshore immigration processing across the globe, the perceived utility of such policies must be considered in light of their considerable, and lasting, psychological, humanitarian, legal and economic costs. Insights from Australia provide timely evidence of the serious and adverse psychiatric consequences of offshore detention and processing. One hundred and forty-five countries, including the UK and Australia, are signatories to the United Nations 1951 Refugee Convention, which outlines a humanitarian obligation to provide protection to people fleeing persecution and human rights violations. Our findings highlight that transferring asylum seekers to offshore facilities – a practice that reportedly costs Australia £11.6 million per person, per year¹⁰ – does not provide this protection. It is not too late for these governments to adopt evidence-based alternatives to offshore processing and immigration detention.