National differences in intelligence and population rates of suicidal ideation, suicide plans, and attempted suicide

Population rates of suicidal ideation, suicide plans or attempted suicide from three independent multinational epidemiological surveys (the WHO/EURO and WHO SUPRE-MISS studies and a third one) were not significantly associated with national IQ figures. This result conflicts with previous evidence from cross-national studies (by Lester and by Voracek) of a positive ecological correlation between level of national intelligence and rates of completed suicide. Across nations, the indicators for the prevalence of suicidal behavior also lacked close correspondence with suicide rates, which may be due to the higher unreliability of assessing covert suicidal behavior (suicide ideas, thoughts, plans, and, to a lesser extent, also suicide attempts) as compared to suicidal behavior that is indisputably overt (completed suicide). Several alternative explanations for the current nil findings are also discussed.