Causal effects of COVID-19 on structural changes in specific brain regions: a Mendelian randomization study

Abstract

Background Previous studies have found a correlation between coronavirus disease 2019 (COVID-19) and changes in brain structure and cognitive function, but it remains unclear whether COVID-19 causes brain structural changes and which specific brain regions are affected. Herein, we conducted a Mendelian randomization (MR) study to investigate this causal relationship and to identify specific brain regions vulnerable to COVID-19. Methods Genome-wide association study (GWAS) data for COVID-19 phenotypes (28,900 COVID-19 cases and 3,251,161 controls) were selected as exposures, and GWAS data for brain structural traits (cortical thickness and surface area from 51,665 participants and volume of subcortical structures from 30,717 participants) were selected as outcomes. Inverse-variance weighted method was used as the main estimate method. The weighted median, MR-Egger, MR-PRESSO global test, and Cochran’s Q statistic were used to detect heterogeneity and pleiotropy. Results The genetically predicted COVID-19 infection phenotype was nominally associated with reduced cortical thickness in the caudal middle frontal gyrus (β = − 0.0044, p = 0.0412). The hospitalized COVID-19 phenotype was nominally associated with reduced cortical thickness in the lateral orbitofrontal gyrus (β = − 0.0049, p = 0.0328) and rostral middle frontal gyrus (β = − 0.0022, p = 0.0032) as well as with reduced cortical surface area of the middle temporal gyrus (β = − 10.8855, p = 0.0266). These causal relationships were also identified in the severe COVID-19 phenotype. Additionally, the severe COVID-19 phenotype was nominally associated with reduced cortical thickness in the cuneus (β = − 0.0024, p = 0.0168); reduced cortical surface area of the pericalcarine (β = − 2.6628, p = 0.0492), superior parietal gyrus (β = − 5.6310, p = 0.0408), and parahippocampal gyrus (β = − 0.1473, p = 0.0297); and reduced volume in the hippocampus (β = − 15.9130, p = 0.0024). Conclusions Our study indicates a suggestively significant association between genetic predisposition to COVID-19 and atrophy in specific functional regions of the human brain. Patients with COVID-19 and cognitive impairment should be actively managed to alleviate neurocognitive symptoms and minimize long-term effects.

Associations between COVID-19 and putative markers of neuroinflammation: A diffusion basis spectrum imaging study

“…Long-term changes in resting-state amplitude of low-frequency fluctuation (ALFF) were also reported for these areas in patients one year after recovery (16). Furthermore, the caudal middle frontal gyrus, exhibiting increased DBSI-HF in our study, has been linked to SARS-CoV-2-induced structural changes such as reduced cortical thickness (93). Interestingly, this COVID-19-related structural alteration within this brain region was further associated with increased inflammation markers in the cerebrospinal fluid (94).…”

Associations between COVID-19 and putative markers of neuroinflammation: A diffusion basis spectrum imaging study

“…Long-term changes in resting-state amplitude of low-frequency fluctuation (ALFF) were also reported for these areas in patients one year after recovery ( Du et al, 2022 ). Furthermore, the caudal middle frontal gyrus, exhibiting increased DBSI-HF in our study, has been linked to SARS-CoV-2-induced structural changes such as reduced cortical thickness ( Zhou et al, 2023 ). Interestingly, this COVID-19-related structural alteration within this brain region was further associated with increased inflammation markers in the cerebrospinal fluid ( Sanabria-Diaz et al, 2022 ).…”

Brain abnormalities in survivors of COVID-19 after 2-year recovery: a functional MRI study

“… 52 Our findings align with a recent Mendelian randomization study that suggested a nominal association between the severe COVID-19 phenotype and reduced cortical surface area in the superior parietal gyrus, pericalcarine and parahippocampal gyrus. 53 Taken together, these evidences indicated that the superior parietal gyrus may be vulnerable to COVID-19 infection, but the precise mechanism is unclear.…”