The study by Pascual et al ^{Reference Pascual, Malagón, Córcoles, Ginés, Soler and García-Ribera1} is interesting and shows a lot of effort by the researchers, who reviewed thousands of cases despite the limitations of research methodology. However, I wonder what prompted the authors to think that immigration could be a risk factor for borderline personality disorder?

Unlike functional illnesses such as depression and schizophrenia, which can develop at any age and can have lots of predisposing factors, personality disorders develop during the early years of childhood and adolescence with most of the personality traits well established by adulthood.

Most of the immigrant groups in this study ^{Reference Pascual, Malagón, Córcoles, Ginés, Soler and García-Ribera1} are from low- and middle-income countries and it is not surprising that fewer people from this group were diagnosed with borderline personality disorder as compared with the indigenous population. We know that the prevalence of personality disorders is greater in high-income/Western countries. ^{Reference Millon2}

If we look at the features and diagnostic criteria for personality disorders, using either DSM–IV or ICD–10, we broadly see two main factors at the base of most of the symptoms: poor coping mechanisms and maladaptive behaviours. Factors commonly seen in Western/high-income countries which contribute to such traits and learned behaviours are the breakdown of community norms ^{Reference Paris3} such as lack of family cohesion, lack of a social support network, dysfunctional families and child abuse. Also, in high-income countries as people enjoy more privileges, they tend to take less responsibility for their actions and expect more and more from the state. We increasingly see more pressure on social services, rather than on parents, to account for the welfare of children.

This does not mean that borderline personality disorder is exclusive to the West, but in the social context we do see more reasons for people in the West to have such traits.

Given the aetiological factors that we are aware of, and the crucial age factor for borderline personality disorder, it is no surprise that immigration is not a risk factor for borderline personality disorder.

This is an interesting study that confirms what was earlier suggested by Tyrer et al ^{Reference Tyrer, Merson, Onyett and Johnson4} and Baleydier et al; ^{Reference Baleydier, Damsa, Schutzbach, Stauffer and Glauser5} however, I am not sure whether a similar study in future would be useful, given that it is unlikely that immigration can be a risk factor for developing borderline personality disorder.

I do, however, agree with the authors that future studies in younger immigrants and second generations who will be more influenced by the Western way of life are likely to be interesting and helpful, especially in terms of clinical management.