Suicidal behaviour in national and international adult adoptees: a Swedish cohort study

Previous studies have shown an elevated risk for suicidal behaviour in adolescent and young adult international adoptees. Comparisons between national and international adoptees in this respect have been inconclusive.

A total of 6,065 international adoptees were compared to 7,340 national adoptees and 1,274,312 non-adopted study subjects, all born between 1963 and 1973 and followed up until 2002 using the National Swedish Registers. Cox regression of person years was used in multivariate analyses to compare risks for suicide death and suicide attempt.

International adoptees had clearly increased risks for suicide attempt (risk ratio 4.5 [95% confidence interval 3.7-5.5]) and suicide death (3.6 [2.6-5.2]) after adjustments for sex, age and socio-economic factors. National adoptees had lower risks than international adoptees, but had increased risks compared to non-adoptees (suicide attempt, 2.8 [2.2-3.5]; suicide death, 2.5 [1.8-3.3]). Biological parents' morbidity explained approximately one third of the increased risk for national adoptees. Female international adoptees' risk for suicide attempt was elevated to an even greater extent than in male international adoptees, when compared to the general population.

Clinicians should be aware that an increased risk for suicide and suicide attempts in international adoptees is a topic that is equally relevant to child and adult psychiatry.