A C Edwards1,2, H Ohlsson3, E K Mościcki4, J Sundquist3,5,6, K Sundquist3,5,6, K S Kendler1,2,7. 1. Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA. 2. Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA. 3. Center for Primary Health Care Research, Lund University, Malmö, Sweden. 4. Department of Epidemiology and Biostatistics, Temple University, Philadelphia, PA, USA. 5. Department of Family Medicine and Community Health, Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. 6. Department of Functional Pathology, School of Medicine, Center for Community-based Healthcare Research and Education (CoHRE), Shimane University, Matsue, Japan. 7. Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, USA.
Abstract
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.
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.
Authors: Kenneth S Kendler; Kristina Sundquist; Henrik Ohlsson; Karolina Palmér; Hermine Maes; Marilyn A Winkleby; Jan Sundquist Journal: Arch Gen Psychiatry Date: 2012-07
Authors: L J Bierut; S H Dinwiddie; H Begleiter; R R Crowe; V Hesselbrock; J I Nurnberger; B Porjesz; M A Schuckit; T Reich Journal: Arch Gen Psychiatry Date: 1998-11