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The Lasting Legacy of COVID-19: Exploring the Long-Term Effects of Infection, Disease Severity, and Vaccination on Health and Cognitive Function

AbstractCOVID-19 affects a variety of organs and systems of the body including the central nervous system. Recent research has shown that COVID-19 survivors often experience neurological and psychological complications that can last for months after infection. We conducted a large internet study using online tests to analyze the effects of SARS-CoV-2 infection, COVID-19 severity, and vaccination on health, intelligence, memory, and information processing precision and speed in a cohort of 4,446 subjects. We found that both SARS-CoV-2 infection and COVID-19 severity were associated with negative impacts on patients’ health. Furthermore, we observed a negative association between COVID-19 severity and cognitive performance. Younger participants had a higher likelihood of SARS-CoV-2 contraction, while the elderly had a higher likelihood of severe COVID-19 and vaccination. The association between age and COVID-19 severity was primarily mediated by older participants’ impaired long-term health. Vaccination was positively associated with intelligence and the precision of information processing. However, the positive association between vaccination and intelligence was likely mediated by achieved education, which was itself strongly associated with the likelihood of being vaccinated.

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Parasitic manipulation or side effects? The effects of past<i>Toxoplasma</i>and<i>Borrelia</i>infections on human personality and cognitive performance are not mediated by impaired health

AbstractBacteriaBorrelia burgdorferi s. l. and even more the protozoanToxoplasma gondiiare known to affect the behavior of their animal and human hosts. Both pathogens infect a significant fraction of human population, and both survive in the host’s body for a long time. The resulting latent infections used to be considered clinically asymptomatic. In the last decade, however, numerous studies have shown that this view may be wrong and both infections can have various adverse effects on human health. Their specific behavioral effects may thus be merely side effects of the general impairment of patients’ health. We tested this hypothesis on a cohort of 7,762 members of internet population using a two-hour-long survey consisting of a panel of questionnaires and performance tests. Our findings confirmed that subjects infected withToxoplasmawere in worse physical and mental health and those infected withBorreliawere in worse physical health than corresponding controls. The infected and noninfected subjects also differed in several personality traits (conscientiousness, pathogen disgust, injury disgust, Machiavellianism, narcissism, tribalism, anti-authoritarianism, intelligence, reaction time, and precision). Majority of the behavioral effects associated withBorreliainfection were the same as those associated withToxoplasmainfection, but some dramatically differed (e.g., performance in the Stroop test). Path analyses and nonparametric partial Kendall correlation tests showed that these effects were not mediated by impaired health of the infected individuals. The results thus contradict predictions of the side effects hypothesis.

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Phylogenetic scale in ecology and evolution

AbstractAimMany important patterns and processes vary across the phylogeny and depend on phylogenetic scale. Yet, phylogenetic scale has never been formally conceptualized and its potential remains largely unexplored. Here, we formalize the concept of phylogenetic scale, review how phylogenetic scale has been considered across multiple fields, and provide practical guidelines for the use of phylogenetic scale to address a range of biological questions.MethodsWe summarize how phylogenetic scale has been treated in macroevolution, community ecology, biogeography, and macroecology, illustrating how it can inform, and possibly resolve, some of the longstanding controversies in these fields. To promote the concept empirically, we define phylogenetic grain and extent, scale-dependence, scaling, and the domains of phylogenetic scale. We illustrate how existing phylogenetic data and statistical tools can be employed to investigate the effects of scale on a variety of well-known patterns and processes, including diversification rates, community structure, niche conservatism, or species-abundance distributions.Main conclusionsExplicit consideration of phylogenetic scale can provide new and more complete insight into many longstanding questions across multiple fields (macroevolution, community ecology, biogeography, macroevolution). Building on the existing resources and isolated efforts across fields, future research centered on phylogenetic scale might enrich our understanding of the processes that together, but over different scales, shape the diversity of life.

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