Cross-national associations of IQ and infectious diseases: Is the prevalence of Corona an exceptional case?

Abstract

BACKGROUND: Previous studies reported negative associations between a country’s mean IQ and economic development at the one side and the prevalence of infectious diseases on the other, arguing that a more rational behavior and better living conditions decreased health risks. The purpose of this study was to transfer these previous findings on the relationship between IQ and the burden of infectious diseases on a cross-national level to the SARS-CoV-2 pandemic. Countries with higher IQ results and rich countries in North-East Asia and the West are more affected by Corona than poorer countries in the Middle East or in sub-Saharan Africa (IQ: _r_IQ↔Cases = .41 and _r_IQ↔Deaths = .28; wealth: _r_GDP/c↔Cases = .45 and _r_GDP/c↔Deaths = .22). Intelligence can have contradicting effects on Corona, i.e., it increases health and makes people more rationally cautious, but at the same time leads to an older population that is more susceptible to corona health problems and allows societies to detect more Corona cases. METHODS: The effects of IQ on the impact of the SARS-CoV-2 pandemic (per capita: reproduction rate_ R_0, hospitalizations due to Corona, Intensive Care Unit treatments, cases, deaths, excess mortality) were controlled in a sample of up to 207 countries for climatic conditions, air pollution, wealth, demographic factors, health burden (e.g., cardiovascular diseases), peoples’ mobility, test coverage and anti-Corona regulations. The stability of effects was checked in six country sub-samples and controlled for the factors named above in regressions with 73 successful runs.  RESULTS: The effect (standardized β) of IQ shows an average negative (reducing) effect of –.19 on the pandemic’s impact. Intelligence has a small effect on the spread of corona and the severity of its consequences. Stronger effects are given by climatic conditions (colder climates) and air pollution. Detailed regressions and additional path analyses show that the reducing effect of IQ is limited to the direct path and the long term (β = .08 in 2020 but –.21 in 2021). CONCLUSIONS: In the context of the SARS-CoV-2 pandemic, the previous findings about the relationship between IQ and the burden of infectious diseases could only be partially reproduced. The assumption of a weakening effect on the impact of the pandemic was confirmed, but only to a limited extent and along unknown ways.