Elsevier

Psychiatry Research

Volume 170, Issues 2–3, 30 December 2009, Pages 286-289
Psychiatry Research

Brief report
Consistency of immigrant suicide rates in Austria with country-of-birth suicide rates: A role for genetic risk factors for suicide?

https://doi.org/10.1016/j.psychres.2008.10.032Get rights and content

Abstract

Multifaceted evidence (family, twin, adoption, molecular genetic, geographic, and surname studies of suicide) suggests genetic risk factors for suicide. The migrant study design is also informative in this context, but underused. In particular, immigrant studies of suicide with a continental European host country are unavailable. The correspondence of suicide prevalence among 22 immigrant groups in Austria (1970–2006) with those of the homelands during the same period was analyzed. Immigrant and homeland suicide rates were significantly positively associated. Controls for age of suicide victim, immigrant group size, national pride, and quality of life in the homelands left the finding essentially unchanged. This correspondence of immigrant and country-of-birth suicide rates is consistent with the assumption of population differences in the prevalence of genetic risk factors for suicide, for which there is emerging evidence.

Introduction

Genetic risk factors for suicide are increasingly recognized (Gershon, 2007). Convergent evidence has flown from a variety of research strategies using family, twin, and adoption study designs (Turecki, 2001, Baldessarini and Hennen, 2004, Brent and Mann, 2005, Voracek, 2007, Voracek and Loibl, 2007), molecular genetic studies of candidate genes within and outside the serotonergic system (Bondy et al., 2006, Li and He, 2006, Laje et al., 2007, Rujescu et al., 2007), and genome scans (Hesselbrock et al., 2004, Cheng et al., 2006). To this literature add suggestive findings from geographic (Marušič and Farmer, 2001, Voracek et al., 2003a, Voracek et al., 2007c, Voracek et al., 2007e, Voracek and Formann, 2004, Marušič, 2005, Voracek, 2006, Voracek and Marušič, 2008) and surname studies of suicide (Marušič et al., 2006, Voracek and Sonneck, 2007). Of note, disbelief about the genetics of suicide is widespread among medical and psychology students and the general population (Voracek and Sonneck, 2006, Kõlves et al., 2007), and such attitudes are measurable (Voracek et al., 2007a, Voracek et al., 2007b, Voracek et al., 2007d).

Another informative approach in this context is migrant studies. This is a common design in genetic epidemiology, frequently employed for investigating genetic versus environmental contributions to the incidence of cancer, diabetes, multiple sclerosis, and other chronic diseases (Khoury et al., 1993, pp. 131–133; Rothman and Greenland, 1998, p. 626). However, this approach is undervalued and underused in research into the genetics of suicide (but see Sher, 1999). With some liberty, immigration may be conceivable as large-scale, naturally occurring “adoption” of adults on a societal level, and adoption studies in turn are a powerful behavioral and psychiatric genetic design to disentangle genetic from environmental effects (Susser, 1985, Voracek, 2007).

The rationale of migrant studies is as follows. Immigrants bring with them specific genetic make-up (including nationally varying genetic risk configurations for diseases or certain behaviors, e.g., suicidality; Sher, 1999) and environmental factors (homeland culture and personal experiences). Unlike genetic factors, influence of homeland culture may fade over time spent in the host country. Similarly, immigrants may have been less ingrained in the homeland culture (at any rate, they emigrated). Immigrants are then exposed to the host country's culture and prevailing environmental factors. Eventually, they reproduce. Importantly, endogamy among immigrants (i.e., the tendency to marry among themselves) is strong (Pagnini and Morgan, 1990). This way, their original genetic make-up (including genetic risk factors) will be more preserved in the second generation than expected by chance (i.e., with random mating). Conversely, homeland culture influences may attenuate among second-generation immigrants.

All of this has obvious implications for studying disease frequencies in immigrants: stable disease frequencies in various immigrant groups that continue to resemble those of their home countries suggest (albeit not conclusively) a possible role for genetic factors, whereas changing disease frequencies that converge from those seen in the home countries to the one seen in the host country support environmental factors. Clearly, this test is more conclusive when based on second-generation immigrants.

There is no strong reason to suspect that migrant studies might only be meaningful and valid for medical conditions (such as those exemplarily listed above), whereas not for complex cognitive–behavioral traits (such as suicidality). A still commonly held misbelief is that the former ones generally show stronger genetic than environmental influences, whereas the latter ones generally stronger environmental than genetic influences. However, this dichotomy seems artificial, simplistic, and is contradicted by many counterexamples. For instance, multiple sclerosis is only modestly heritable, but shows strong environmental effects (Oksenberg et al., 2008). On the other hand, the totality of evidence from twin studies of suicide indicates that additive genetic factors contribute substantially to the risk of suicide (heritability estimates: 30–55%), as do nonshared environmental factors (the prenatal environment and personal experiences), but shared environmental factors (family, peers, and social context) do not and are negligible (Voracek and Loibl, 2007). Consequently, shared environmental factors among immigrants (such as preserved cultural, dietary, or religious practices) probably are of less importance for their risk of suicidal behavior than other sources (genetic and nonshared environmental factors).

A number of studies have investigated the resemblance of immigrant and country-of-birth suicide rates (Sainsbury and Barraclough, 1968, Lester, 1972, Barraclough, 1973, Sainsbury, 1983). Originally designed to demonstrate the veridicality of national differences in suicide rates, these studies invariably found moderate to strong positive correlations between immigrant and country-of-birth suicide rates. Most tests were conducted for the USA as the host country (e.g., Dublin, 1963), but the central finding was shown to generalize to other classic immigration countries as well (Australia: Burvill et al., 1973; Canada: Kliewer and Ward, 1988; Sweden: Ferrada-Noli, 1997; UK: Raleigh and Balarajan, 1992). Even more intriguing is the fact that the finding also replicated among second-generation immigrants (Hjern and Allebeck, 2002).

Genetic risk factors for suicide have rarely been considered to account for this phenomenon (for an exception, see Ferrada-Noli, 1997). Most commentators invoked some continuing cultural influences (mostly not further specified) as likely causes for the consistency of immigrant and country-of-birth suicide rates. However, given the logic of the migrant study design, as discussed above, this stance is not particularly convincing.

Studies of immigrant suicide are available for some classic immigration countries, but not for other or smaller nations. Most of the evidence is from some decades ago, so topical data are scarce. In particular, there are no data for continental Europe. Accordingly, this study presents topical (1970–2006) data from Austria, which is small, not a classic immigration country, and located in Central Europe.

Section snippets

Methods

Data on all 65,206 suicides (71.2% males) officially registered in Austria 1970–2006 were obtained from Statistics Austria. Owing to the high autopsy rate in the country, the reliability of suicide statistics is high (Voracek et al., 2003b). 1724 suicides (2.6% of all) were by non-citizens. Suicides of stateless persons and cases with unidentified or unclear nationality were omitted, and an inclusion criterion of at least 4 cases per nationality during the study period was applied. This left

Results

The ranking of suicide prevalence among the 22 immigrant groups corresponded significantly to the one of the homelands (rs = 0.45, P = 0.03, two-tailed). Removal of the two outliers (Hungary and USSR; Fig. 1) would raise this figure (rs = 0.57, P = 0.008), as would removal of the two genetically most heterogeneous countries (India and USSR; rs = 0.55, P = 0.01). Removal of the two Islamic countries (Iran and Turkey), whose datapoints accorded to the general trend and were not outliers, would consequently

Discussion

With 22 nationalities available for analysis, this first immigrant study of suicide from continental Europe is the second-largest conducted so far (Kliewer and Ward, 1988, could consider 29 nationalities). Previous findings from classic immigration countries, larger nations, and earlier decades replicated in the current study in a small nation (not a classic immigration country) and for a more recent period: taking Austria as the host country, a significant positive association of immigrant and

Acknowledgements

This research was in partial fulfillment of the first author's D.M.Sc. degree requirements at the Medical University of Vienna. Lisa Mariella Loibl was supported by a Young Researcher Mini Grant from the Dean's Office of the School of Psychology, University of Vienna.

References (58)

  • BaldessariniR.J. et al.

    Genetics of suicide: an overview

    Harvard Review of Psychiatry

    (2004)
  • BarracloughB.M.

    Differences between national suicide rates

    British Journal of Psychiatry

    (1973)
  • BondyB. et al.

    Genetics of suicide

    Molecular Psychiatry

    (2006)
  • BrentD.A. et al.

    Family genetic studies, suicide, and suicidal behavior

    American Journal of Medical Genetics C: Seminars in Medical Genetics

    (2005)
  • BurvillP.W. et al.

    Deaths from suicide, motor vehicle accidents and all forms of violent death among migrants in Australia, 1962–1966

    Acta Psychiatrica Scandinavica

    (1973)
  • ChengR. et al.

    Genome-wide linkage scan in a large bipolar disorder sample from the National Institute of Mental Health genetics initiative suggests putative loci for bipolar disorder, psychosis, suicide, and panic disorder

    Molecular Psychiatry

    (2006)
  • DuL. et al.

    Tryptophan hydroxylase gene 218A/C polymorphism is not associated with depressed suicide

    International Journal of Neuropsychopharmacology

    (2000)
  • DublinL.I.

    Suicide: A Sociological and Statistical Study

    (1963)
  • Ferrada-NoliM.

    A cross-cultural breakdown of Swedish suicide

    Acta Psychiatrica Scandinavica

    (1997)
  • GershonE.S.

    Genes and environment in suicidality

    American Journal of Psychiatry

    (2007)
  • HesselbrockV. et al.

    The search for genetic risk factors associated with suicidal behavior

    Alcohol: Clinical and Experimental Research

    (2004)
  • HjernA. et al.

    Suicide in first- and second-generation immigrants in Sweden: a comparative study

    Social Psychiatry and Psychiatric Epidemiology

    (2002)
  • KhouryM.J. et al.

    Fundamentals of Genetic Epidemiology

    (1993)
  • KliewerE.V. et al.

    On the convergence of immigrant suicide rates to those in the destination country

    American Journal of Epidemiology

    (1988)
  • KõlvesK. et al.

    Knowledge about suicide and local suicide prevalence: comparison of Estonia and Austria

    Perceptual and Motor Skills

    (2007)
  • LajeG. et al.

    Genetic markers of suicidal ideation emerging during citalopram treatment of major depression

    American Journal of Psychiatry

    (2007)
  • LesterD.

    Migration and suicide

    Medical Journal of Australia

    (1972)
  • LesterD.

    The validity of national suicide rates

    British Journal of Psychiatry

    (1980)
  • LiD. et al.

    Further clarification of the contribution of the tryptophan hydroxylase (TPH) gene to suicidal behavior using systematic allelic and genotypic meta-analyses

    Human Genetics

    (2006)
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