Variation in European suicide rates is better accounted for by latitude and longitude than by national percentage of Finno-Ugrians and Type O blood: a rebuttal of Lester and Kondrichin (2004)

Socioeconomic and environmental contexts of suicidal rates in a latitudinal gradient: Understanding interactions to inform public health interventions

Suicide results from complex interactions between biological, psychological, and socioeconomic factors. At the population level, the study of suicide rates and their environmental and social determinants allows us to disentangle some of these complexities and provides support for policy design and preventive actions. In this study we aim to evaluate the associations between environmental and socioeconomic factors and demographically stratified suicide rates on large temporal and spatial scales. Our dataset contains information about yearly suicides rates by sex and age from 2000 through 2017 along a 4000 km latitudinal gradient. We used zero-inflated negative binomial models to evaluate the spatio-temporal influence of each environmental and socioeconomic variable on suicide rates at each sex/age combination. Overall, we found differential patterns of associations between suicide rates and explanatory variables by age and sex. Suicide rates in men increases in middle and high latitude regions and intermediate age classes. For adolescent and adult women, we found a similar pattern with an increase in suicide rates at middle and high latitudes. Sex differences measured by the male/female suicide ratio shows a marked increase with age. We found that cloudiness has a positive effect on suicide rates in both men and women 24 years old or younger. Regional poverty shows a major impact on men in age classes above 35 years old, an effect that was absent in women. Alcohol and marijuana consumption showed no significant effect sizes. Our findings support high spatio-temporal variability in suicide rates in interaction with extrinsic factors. Several strong differential impacts of environmental and socioeconomic variables on suicide rates depending on sex and age were detected. These results suggest that the design of public policies and interventions to reduce suicide prevalence need to consider the local social and environmental contexts of target populations.

Ancestry and different rates of suicide and homicide in European countries: A study with population-level data

INTRODUCTION

There are large differences in suicide rates across Europe. The current study investigated the relationship of suicide and homicide rates in different countries of Europe with ancestry as it is defined with the haplotype frequencies of Y-DNA and mtDNA.

MATERIAL AND METHODS

The mortality data were retrieved from the WHO online database. The genetic data were retrieved from http://www.eupedia.com. The statistical analysis included Forward Stepwise Multiple Linear Regression analysis and Pearson Correlation Coefficient (R).

RESULTS

In males, N and R1a Y-DNA haplotypes were positively related to both homicidal and suicidal behaviors while I1 was negatively related. The Q was positively related to the homicidal rate. Overall, 60-75% of the observed variance was explained. L, J and X mtDNA haplogroups were negatively related with suicide in females alone, with 82-85% of the observed variance described.

DISCUSSION

The current study should not be considered as a study of genetic markers but rather a study of human ancestry. Its results could mean that research on suicidality has a strong biological but locally restricted component and could be limited by the study population; generalizability of the results at an international level might not be possible. Further research with patient-level data are needed to verify whether these haplotypes could serve as biological markers to identify persons at risk to commit suicide or homicide and whether biologically-determined ancestry could serve as an intermediate grouping method or even as an endophenotype in suicide research.

Suicide rate trends in the Slovak Republic in 1993-2015

BACKGROUND

Suicide is a significant public health issue worldwide, resulting in loss of lives, and burdening societies.

AIMS

To describe and analyze the time trends of suicide rates (SRs) in the Slovak Republic in 1993-2015 for targeted suicide prevention strategies.

METHODS

Data for this study were obtained from the mortality database of the Statistical Office of the Slovak Republic. Crude and standardized annual SRs were calculated. Trends and relative risks of suicide according to age and sex were analyzed by joinpoint regression and negative binomial regression.

RESULTS

In total, there were 14,575 suicides in the Slovak Republic in the period 1993-2015 (85.3% were men). The overall average age-standardized SR for the study period was 11.45 per 100,000 person years. The rate increases with age, the highest is in men aged 75+ (42.74 per 100,000 person years). Risk of suicide is six times higher in men than in women and nine times higher in men than in women in the age group 25-34. The time trend of SRs is stable or decreasing from 1993 to 2007, but increasing after 2007, corresponding with increased unemployment rate in the country.

CONCLUSION

The SR in the Slovak Republic is slightly below the average of Organisation for Economic Co-operation and Development (OECD) nations. Highest SR is observed in men of working age and in retirement. Society might benefit from a strategy of education for improving the recognition of suicide risks.

Belief and Disbelief in the Existence of Genetic Risk Factors for Suicide: Cross-Cultural Comparisons

There is evidence for widespread disbelief in the genetics of suicide, despite recent research progress in this area and convergent evidence supporting a role for genetic factors. This study analyzed the beliefs held in 8 samples (total N=1224) of various types (psychology, medical, and various undergraduates, psychology graduates, and the general population) from 6 countries located on 3 continents (Austria, Canada, Malaysia, Romania, United Kingdom, and the USA). Endorsement rates for the existence of genetic risk factors for suicide ranged from 26% and 30% (Austrian psychology undergraduates and general population) to around 50% (psychology undergraduates in the USA and United Kingdom). In the 8 samples, respondents' sex, age, religiosity, political orientation, and other demographic variables were, for the most part, unrelated, but overall knowledge about suicide throughout was related positively to endorsement rates. Consistent with previous research, across a considerable variety of sample types and cultural settings there was no evidence for a clear majority believing in genetic bases for suicide.

Correlates, Item-Sequence Invariance, and Test-Retest Reliability of the Beliefs in the Inheritance of Risk Factors for Suicide Scale (BIRFSS)

Genetic contributions to suicide are increasingly recognized. This study further validated the novel 22-item Beliefs in the Inheritance of Risk Factors for Suicide Scale (BIRFSS), which assesses individuals' beliefs about the genetics of suicide. Data from 155 mainly Austrian psychology undergraduates (42 men, 113 women) indicated adequate internal scale consistency and 2-mo. test-retest reliability. Scores were temporally stable and factor analysis of items yielded a dominant first factor. Scores were positively related to general beliefs about genetic determinism and to positive attitudes towards psychiatric genetic research (convergent validity), but unrelated to lay theories of suicide, locus of control, self-reported religiosity and political orientation, religious and spiritual beliefs, and social dominance orientation (discriminant validity). Effects of sex, age, and nationality (Austrian vs other) on scores were negligible. Item statistics corresponded strongly to those obtained from administering the item sequence in reverse order. Item statistics were strongly correlated with those observed in two previous validation studies, suggesting cross-sample robustness of the item-performance indicators of this measure. The scale shows potential for basic research and curriculum evaluation.

Digit ratio (2D:4D), ABO blood type, and the Rhesus factor

Twin and family study findings indicate a substantial heritability of digit ratio (2D:4D), a putative marker for the masculinizing effects of prenatal androgen exposure. Functional polymorphisms of the X-linked androgen receptor gene, i.e., androgen sensitivity, contribute somewhat to the expression of 2D:4D in men, but otherwise the genetics of 2D:4D is unknown. This study investigated differences in 2D:4D by self-reported ABO blood type and Rhesus factor, two easily collectible genetic traits, in two samples (combined N=1273). Effects of blood groups on 2D:4D were small and not significant in all tests in both samples; however, two consistent patterns emerged across samples. Of the ABO types, AB had the lowest right-hand 2D:4D, the highest left-hand 2D:4D, and the lowest right-minus-left difference in 2D:4D, and Rhesus factor Rh- had higher left-hand 2D:4D and lower right-minus-left difference in 2D:4D than Rh+. If replicable, this may suggest genes contributing to the expression of 2D:4D reside in the vicinity of the gene loci (chromosomal locations: 9q34.2 and 1p36.11) of these blood groups or pleiotropic effects of the blood-group genes.

Consistency of immigrant and country-of-birth suicide rates: a meta-analysis

OBJECTIVE

Multifaceted evidence (family, twin, adoption, molecular genetic, geographic and surname studies of suicide) suggests genetic risk factors for suicide. Migrant studies are also informative in this context, but underused. In particular, a meta-analysis of the associations of immigrant (IMM) and country-of-birth (COB) suicide rates is unavailable.

METHOD

Thirty-three studies, reporting IMM suicide rates for nearly 50 nationalities in seven host countries (Australia, Austria, Canada, England, the Netherlands, Sweden and the USA), were retrieved.

RESULTS

Total-population IMM and COB suicide rates were strongly positively associated (combined rank-order correlation across 20 eligible studies: 0.65, 95% CI: 0.56-0.73, P < 10(-9)). The effect generalized across both sexes, host countries and study periods.

CONCLUSION

Following the logic of the migrant study design of genetic epidemiology, the correspondence of IMM and COB suicide rates is consistent with the assumption of population differences in the prevalence of genetic risk factors for suicide.

A further test of the Finno-Ugrian Suicide Hypothesis: correspondence of county suicide rates in Romania and population proportion of ethnic Hungarians

Across the 42 counties of Romania, the total suicide rate and the population percentage of ethnic Hungarians were strongly positively interrelated (79% attributable variance). Counties with the strongest Hungarian minority had suicide rates converging to (or exceeding) the suicide rate for Hungary, which rate is high. Of a set of about 20 vital statistics and socioeconomic indicators, only life expectancy predicted a significant increment of further variance in the suicide rates. However, this effect was small, adding merely 3% further variance explained to 79% already accounted for. Overall, the findings are supportive of the Finno-Ugrian Suicide Hypothesis, i.e., the notion that geographic patterns of suicide prevalence may be partially due to genetic differences between populations. Supplemental analyses of a questionnaire item which specifically queried this study's main finding indicated widespread disbelief of this fact of suicide prevalence across a variety of samples, including two samples from Romania.

Genetics of suicide: a systematic review of twin studies

OBJECTIVES

Convergent evidence from a multitude of research designs (adoption, family, genomescan, geographical, immigrant, molecular genetic, surname, and twin studies of suicide) suggests genetic contributions to suicide risk. The present account provides a comprehensive and up-to-date review of the twin studies on this topic.

METHODS

A total of 32 studies (19 case reports, 5 twin register-based studies, 4 population-based epidemiological studies, 4 studies of surviving co-twins) located through extensive literature search strategies are summarized and discussed here. This literature corpus was published between 1812 and 2006 in six languages and reports data from 13 countries.

RESULTS

A meta-analysis of all register-based studies and all case reports aggregated shows that concordance for completed suicide is significantly more frequent among monozygotic than dizygotic twin pairs. The results of co-twin studies rule out exclusively psychosocially based explanations of this pattern. Population-based epidemiological studies demonstrate a significant contribution of additive genetic factors (heritability estimates: 30-55%) to the broader phenotype of suicidal behavior (suicide thoughts, plans and attempts) that largely overlaps for different types of suicidal behavior and is largely independent of the inheritance of psychiatric disorders. Nonshared environmental effects (i.e. personal experiences) also contribute substantially to the risk of suicidal behavior, whereas effects of shared (family) environment do not.

CONCLUSIONS

The totality of evidence from twin studies of suicide strongly suggests genetic contributions to liability for suicidal behavior. To further research progress in this area, an extensive discussion of design limitations, shortcomings of the literature and further points is provided, including sources of bias, gaps in the literature, errors in previous reviews, age and sex effects and twin-singleton differences in suicide risk, and notes from a history-of-science view.

Surname study of suicide in Austria: differences in regional suicide rates correspond to the genetic structure of the population

OBJECTIVES

There is convergent evidence from adoption, family, geographical, immigrant, molecular genetic, twin and, most recently, surname studies of suicide for genetic contributions to suicide risk. Surnames carry information about genetic relatedness or distance and, in patrilineal surname systems, are a close substitute for Y-chromosome markers and haplotypes, since surname transmission is similar to the transmission of the nonrecombining part of the Y chromosome. This study investigated whether differences in regional suicide rates correspond to the genetic structure of the Austrian population.

METHODS

Differences in district-level standardized suicide rates 1988-94 between the five major surname regions identified for Austria were analyzed. The surname regions used in the analysis reflect the contemporary population structure and closely follow the natural borders found in the topography of Austria, less so its administrative division into nine states.

RESULTS

Surname region accounted for a significant (P < 0.001) and substantial (38%) portion of the variance in district-level suicide rates. Adjusting the suicide rates for a set of five social and economic indicators that are established ecological correlates of suicide prevalence (income, and rates of the divorced, unemployed, elderly and Roman Catholics) left the results essentially unchanged.

CONCLUSIONS

Regional differences in suicide rates within Austria correspond to the genetic structure of the population. The present evidence adds to related findings from geographical and surname studies of suicide that suggest a role for genetic risk factors for suicidal behavior. Genetic differences between subpopulations may partially account for the geography of suicide. Study limitations and directions for future research are discussed.

Testing the Finno-Ugrian suicide hypothesis: replication and refinement with regional suicide data from eastern Europe

Multiple lines of evidence indicate specific genetic contributions to suicidal behavior. In particular, geographic studies support the Finno-Ugrian Suicide Hypothesis, i.e., genetic differences between populations may partially account for geographic patterns of suicide prevalence. Specifically, within Europe the high suicide-rate nations constitute a contiguous J-shaped belt. The present research replicated and extended 2003 findings of Voracek, Fisher, and Marusic with new data. Across 37 European nations, an interaction term of squared latitude multiplied with longitude (quantifying the J-shaped belt) accounted for 32% of the cross-national variance in total suicide rates alone, while latitude accounted merely for 18% of variance over and above those. Refined analysis included regional data from countries critical for testing the hypothesis (89 regions of Belarus, western Russia, and the Ukraine) and yielded an even more clear-cut pattern (56% and 3.5%, respectively). These results are consistent with the Finno-Ugrian Suicide Hypothesis. Study limitations and directions for further research are discussed.

Beliefs in the Inheritance of Risk Factors for Suicide Scale: Development, Reliability, Stability, and Convergent and Discriminant Validity

Findings from adoption, family, geographical, immigrant, molecular genetic, surname, and twin studies suggest genetic risk factors have a role in suicidal behavior. However, related mental health literacy (knowledge and beliefs) even of future health-care professionals who will be concerned with suicide lag behind this research progress. As no scale for assessing such beliefs is available, the 22-item Beliefs in the Inheritance of Risk Factors for Suicide Scale was constructed, its contents rated by experts in a validation survey and administered to samples of 70 medical and 165 psychology students. Medical students held stronger beliefs in the genetics of suicide than psychology students. Internal scale consistency and test-retest reliability were assessed as adequate. Factor analysis of the 22 items yielded a dominant first factor. Scores were positively related to knowledge about suicide (convergent validity) but for the most part unrelated to lay theories of suicide, political orientation, religiosity, and social desirability (discriminant validity). This novel scale shows potential for assessing individuals' beliefs about the genetics of suicide. Applications may include basic research, educational contexts, and evaluation of professional training.

Ancestry, genes, and suicide: a test of the Finno-Ugrian Suicide Hypothesis in the United States

There is now convergent evidence from classic quantitative genetics (family, twin, and adoption studies) and molecular genetic studies for specific genetic risk factors for suicidal behavior. This emerging research field has recently been supplemented by geographical studies concerned with the Finno-Ugrian Suicide Hypothesis (FUSH), which states that population differences in genetic risk factors may partially account for conspicuous geographical patterns seen in suicide prevalence. In particular, the European high-suicide-rate nations constitute a contiguous, J-shaped belt, spanning from Finland to Austria. This area maps onto the second principal component identified for European gene distribution, most likely reflecting a major migration event of the past (i.e., the ancestral adaptation to cold climates and the Uralic language dispersion) still detectable in modern European populations. The present research tested the hypothesis in the United States. Consistent with the hypothesis, available historical (1913-1924 and 1928-1932) U.S. state suicide rates were uniformly positively associated with available state proportions of reported American ancestries from European high-suicide-rate countries (Hungary, Lithuania, Poland, Russia, Slovakia, and the Ukraine). However, contrary to the hypothesis, available contemporary (1990-1994) suicide rates were uniformly negatively associated with these ancestry proportions. The findings of this first test outside Europe are therefore conflicting. A proposal based on the geographical study approach is offered to further the progress of investigations into the genetics of suicide.