Prior research based on Swedish data suggests that collective optimism, as measured by monthly incidence of suicides, correlates inversely with selection in utero against male twins in a population. We test this finding in the US, which reports the highest suicide rate of all high-income countries, and examine whether monthly changes in overall suicides precede changes in the ratio of male twin to male singleton live births. Consistent with prior work, we also examine as a key independent variable, suicides among women aged 15−49 years. We retrieved monthly data on suicides and the ratio of male twin to singleton live births from CDC WONDER, 2003 to 2019, and applied Box-Jenkins iterative time-series routines to detect and remove autocorrelation from both series. Results indicate that a 1% increase in monthly change in overall suicides precedes a 0.005 unit decline in male twin live births ratio 6 months later (coefficient = −.005, p value = .004). Results remain robust to use of suicides among reproductive-aged women as the independent variable (coefficient = −.0012, p value = .014). Our study lends external validity to prior research and supports the notion that a decline in collective optimism corresponds with greater selection in utero.

Background: An epidemiological transition hypothesis has been developed to explain simultaneously wide cross-national variations in elderly suicide rates, trends over time for elderly suicide rates and age-associated trends in suicides rates. This speculative hypothesis suggests that there is a curvilinear (inverted U-shaped curve) relationship between elderly suicide rates and socioeconomic status fitting the quadratic equation y = a + bx − cx2 (where y is the suicide rate, x is the socioeconomic status, and a, b and c are constants).

Methods: The predicted curvilinear relationship between elderly suicide rates and gross national domestic product (GDP), a measure of socioeconomic status, fitting the above quadratic equation was examined with a curve estimation regression model using data from the World Health Organization.

Results: The relationship between suicide rates in both sexes in the age-bands 65–74 and 75+ years and the GDP was curvilinear (inverted U-shaped curve) and fitted the above quadratic equation, and was statistically significant (at least p<0.05) in all four groups.

Conclusions: Caution should be exercised in accepting this model of the epidemiological transition hypothesis for elderly suicide rates because it is generated from cross-sectional data using an ecological design. Ideally, this model requires rigorous testing by following selected countries of low socioeconomic status over time as they develop socioeconomically.

Background: The elderly are at high risk of developing tuberculosis. The prevalence and incidence of depression and anxiety are higher in those with tuberculosis than in the general population. A positive correlation between national suicide rates and rates of mortality due to tuberculosis has been reported.

Methods: The relationships between elderly suicide rates and (i) the prevalence of tuberculosis, (ii) the proportion of detected cases of tuberculosis, and (iii) the proportion of cured cases of tuberculosis were examined in a cross-national study using data from the World Health Organization and the United Nations.

Results: There were no significant correlations between elderly suicide rates and the prevalence of tuberculosis and the proportion of detected cases of tuberculosis. There were weak but significant negative correlations between the proportion of cured cases of tuberculosis and suicide rates for both sexes in both elderly age-bands.

Conclusion: Caution should be exercised in interpreting the findings and the direction of the causal relationship from this cross-sectional ecological study because of ecological fallacy. However, if the findings are true then potentially the study has important implications for prevention of elderly suicides, particularly in countries with a high prevalence of tuberculosis.

Background: Studies examining trends in elderly suicide rates over time reported a decline, an increase and no change. A cross-national study was undertaken to examine the current status of trends over time in elderly suicide rates because previous cross-national studies were well over a decade old.

Methods: Trends in suicide rates for males and females in the age-bands 65–74 years and 75+ years over a 10-year period were examined using data from the World Health Organization website for all the listed countries.

Results: The main findings were: (1) elderly suicide rates either declined or remained unchanged over the 10-year period in most countries; and, (2) suicide rates in both sexes in both the age-bands, over the 10-year period, declined in several European countries, and remained unchanged in several Central and South American countries, Eastern European countries and countries of the former Soviet Union.

Conclusions: Potential explanations for regional and cross-national variations in trends over time in elderly suicide rates include cross-national differences in trends over time in the prevalence of mental illness in the elderly, socioeconomic factors, cultural factors, the availability of appropriate healthcare services, and public health initiatives to improve the detection and treatment of mental illness, mental health and suicide prevention.

Background: Cultural factors may influence cross-national variations in elderly suicide rates.

Methods: A cross-national study examining the relationship between elderly suicide rates and elderly dependency ratios was conducted with the a priori unidirectional hypothesis that lower elderly dependency ratios (ratio of people over the age of 65 years to people under the age of 65 years) may imply a greater number of younger people being potentially available to provide support and respect to the elderly and to hold them in high esteem, and this would lead to a reduction in elderly suicide rates. Data on elderly suicide rates, and the total number of elderly and young people were ascertained from the World Health Organization website.

Results: Significant positive correlations were found between the natural logarithm of suicide rates, in both sexes in two elderly age-bands (65–74 years and 75+ years), and the elderly dependency ratio for males, females and both sexes combined.

Conclusions: The impact of elderly dependency ratios on elderly suicide rates may interact with and be modified and mediated through cultural factors. The contribution of cross-national differences in cultural factors on elderly suicide rates require further study by formally measuring cultural factors with validated instruments.

Background: Suicide rates generally increase with age. With the emergence of studies from several countries without an increase in suicides rates with aging, a cross-national study examining the relationship between suicide rates and age was undertaken.

Methods: The relationship between suicide rates and age was examined by ascertaining suicide rates in both sexes in seven age-bands 16–24 years, 25–34 years, 35–44 years, 45–54 years, 55–64 years, 65–74 years and 75+ years, from the World Health Organization website for all the listed countries (N = 62).

Results: The main findings were: (i) there was a significant increase in suicide rates with increasing age in males and females in 25 and 27 countries respectively; (ii) there was no significant increase in suicide rates with increasing age in males and females in 31 and 29 countries respectively; (iii) suicide rates were the highest in the younger age-bands in countries without a significant increase in male suicides rates with increasing age; (iv) countries without a significant increase in the suicide rate with increasing age in both sexes, females only and males only demonstrated regional clustering; and, (v) in a small number of countries suicide rates declined with increasing age.

Conclusions: Potential explanations for regional and cross-national variations in the relationship between suicide rates and age require further study.