Genetic factors in suicide: reassessment of adoption studies and individuals' beliefs about adoption study findings.
BACKGROUND
Based on multifaceted evidence (family, twin, adoption, molecular genetic, geographic, immigrant, and surname studies of suicide), the genetics of suicide is increasingly recognized. However, a comprehensive, stand-alone review of adoption studies in this area is unavailable, nor are there data on what people actually believe about adoption study findings.


OBJECTIVE
To reassess the available adoption studies of suicide and to provide novel data on beliefs relating to these.


METHODS
Key findings of the 3 existing adoption studies of suicide were reviewed and subjected to a meta-analysis. Beliefs pertaining to these were analyzed in 10 samples (total N = 1379) of different types (medical and psychology students, general population) from 6 countries.


RESULTS
The combined evidence from adoption studies clearly supported genetic factors in suicide. Critical tests showed that suicide runs in the biological families of suicided (as well as schizophrenic or affectively ill) adoptees, but not in those of demographically matched healthy control adoptees alive (relative risk RR = 8.38, p = 0.0002). Individuals' beliefs about the plausibility of these findings were inconsistent and self-contradictory. Particularly, it was widely disbelieved that adoptees' risk of suicide resembles the one of their biological, not their adoptive, relatives (which is the case).


CONCLUSIONS
Despite demonstrating a significant genetic effect, the evidence base from adoption studies of suicide is narrow. To broaden the evidence remains an important research agenda. Gaps in and deficiencies of this specific literature as well as general limitations of adoption study designs are discussed.
Voracek
Martin
M
Department of Basic Psychological Research, School of Psychology University of Vienna, Liebiggasse 5, Rm 03-42, A-1010 Vienna, Austria. martin.voracek@univie.ac.at
D000300:Adoption / Q000523:psychology*; D003430:Cross-Sectional Studies; D003469:Culture; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D019964:Mood Disorders / Q000235:genetics* / Q000523:psychology; D012307:Risk Factors; D012559:Schizophrenia / Q000235:genetics*; D012931:Social Environment; D013405:Suicide / Q000523:psychology* / Q000706:statistics & numerical data