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Geographic proximity is associated with transmission of suicidal behaviour among siblings
Author(s) -
Edwards A. C.,
Ohlsson H.,
Mościcki E. K.,
Sundquist J.,
Sundquist K.,
Kendler K. S.
Publication year - 2019
Publication title -
acta psychiatrica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.849
H-Index - 146
eISSN - 1600-0447
pISSN - 0001-690X
DOI - 10.1111/acps.13040
Subject(s) - sibling , demography , closeness , confounding , poison control , psychology , sibling relationship , injury prevention , medicine , developmental psychology , medical emergency , mathematical analysis , mathematics , sociology
Objective The aim of this study was to clarify the role of ‘contagion’, or social transmission, in risk of suicidal behaviour (SB) among siblings. Methods We followed Swedish sibling pairs until one of them (S1; N = 111,848) was registered for a suicide attempt or completion. We tested the effect of geographic proximity between siblings on risk of a first SB registration of S1's sibling (S2). To control for familial confounding, we conducted complementary analyses of sibling trios ( N = 701), comparing risk in different siblings as a function of their respective proximity to S1. Results The best‐fitting model across sibling pairs included an effect of distance between siblings (HR = 0.96, 95% CI = 0.93–0.99). Hazard ratios declined quickly up to 25 km and largely stabilized beyond 150 km. Across all pairs, a larger age difference between siblings was associated with reduced SB risk (HR = 0.96 95% CI = 0.93–0.98). Findings were consistent within the sibling trios. Conclusions Consistent with the concept of suicide contagion, risk of suicidal behaviour subsequent to a sibling's suicide completion or attempt is higher as a function of sibling closeness. These findings are robust to potentially confounding familial factors.