Dados do Trabalho

Título

Absence of strain-specific effects on cognitive dysfunction after COVID-19: analyses of 454 subjects

Resumo

Introduction: Long-term effects on cognitive function are present even after mild COVID-19 infection, leading the WHO to coin the term “long COVID”. Recent reports suggest that the viral strain plays a role in determining long-COVID symptoms.
Objective: This study aims to evaluate the effect of the presumed viral strain on different cognitive domains.
Material and methods: data from UNICAMP’s NeuroCOVID cohort was used in the study. The date of the positive test was used as a proxy to separate subjects in different presumed strain groups according to the prevalent strain Fiocruz database (http://www.genomahcov.fiocruz.br) Subjects were evaluated with a neuropsychological battery consisting of the following tests: phonetic fluency (FAS), semantic fluency (SF: animals), logic memory (immediate and late recall), Rey-Osterrieth complex figure test (copy and recall), colored trails test A and B, 9-hole peg test (dominant and nondominant hand) and the five digits test (reading, counting, choice, alternation, inhibition and flexibility), comprising 16 cognitive measures. We converted Test scores to Z-scores using normative tables for sex, age and education. The MANOVA test was initially used to test for strain effects on any cognitive domain, followed by one-way ANOVA tests for each domain.
Results: 454 subjects (15 years of education; 88 days after diagnosis) were divided into 5 presumed strain groups: original strain (247), original+P2 (36), P2 (86), gamma+P2 (50) and delta (6). Data for all tests were available for 141 subjects. One-way MANOVA in this subset showed significant strain effects (p=0.046). Nonetheless, post-hoc tests showed no strain effects on any of the cognitive tests. SF showed a marginally significant effect (n=392, p=0.056) due to better performances in the original+P2 and P2 strains. FDT reading subtest was marginally significant (n=323, p=0.073) due to better test performances in the P2 and delta presumed strain groups.
Discussion: although a global test effect was observed, individual test data could not show significant effects of the presumed strain. Marginal significance in semantic fluency and FDT reading subtest mainly accounted by presumed P2 strain subjects’ better performances, suggesting P2-related post-COVID syndrome may relatively spare processing speed. Regardless of the absence of strain-specific effects, post-COVID subjects in the cohort showed significant cognitive deficits, which may impair workability and quality of life.

Palavras Chave

long COVID, neuropsychology, viral strain