COVID-19 is associated with changes in brain function and structure: A multimodal meta-analysis of neuroimaging studies

Persistent neurocognitive deficits in long COVID: Evidence of structural changes and network abnormalities following mild infection

This study aimed to investigate the neurocognitive deficits, structural brain alterations, and network abnormalities in individuals who had a mild SARS-CoV-2 infection, with and without brain fog, as a symptom of long COVID. A cross-sectional study was conducted involving 75 participants, categorized into three groups: 24 healthy controls (HCs), 26 COVID-19 survivors without brain fog (woFOG), and 25 with brain fog (wFOG). Neuropsychological assessments included the Free and Cued Selective Reminding Test (FCSRT) and Addenbrooke's Cognitive Examination-Revised (ACE-R). Structural and functional brain alterations were examined using voxel-based morphometry (VBM) and resting-state functional MRI (rs-fMRI). The wFOG group exhibited significant cognitive impairments, particularly in delayed free recall, attention, memory, and visuospatial skills, compared to both the woFOG and HC groups. Structural MRI analyses revealed reduced gray matter concentrations (GMC) in the left inferior temporal gyrus, left fusiform gyrus, and right orbital gyri in both COVID-19 groups relative to HCs. Additionally, the wFOG group exhibited further GMC reductions in the bilateral caudate nuclei, right putamen/pallidum, and amygdala compared to the woFOG group. rs-fMRI analyses demonstrated altered connectivity patterns in COVID-19 survivors, characterized by increased connectivity in the default mode network and visual networks, alongside decreased connectivity in the dorsal attention network. These findings indicate that even mild COVID-19 can result in persistent neurocognitive deficits, structural brain alterations, and functional network abnormalities, both in individuals with and without brain fog. The observed changes highlight the importance of long-term monitoring and targeted interventions to address potential cognitive and neurological consequences of long COVID.

Cognitive Slowing, Dysfunction in Verbal Working Memory, Divided Attention and Response Inhibition in Post COVID-19 Condition in Young Adults

After COVID-19 infection, about 30% of people have clinically persisting symptoms, characterized as Post COVID-19 Condition (PCC). One of the most reported symptoms in PCC is cognitive dysfunction, yet there are only a few studies investigating long-term effects on different domains of cognitive function. A total of 107 young adults, university students aged 18-34 years, participated. In total, 68.2% had contracted SARS-CoV-2; 21.9% showed PCC. Three groups were compared: no-C19 (COVID-19-negative controls), C19 (COVID-19-recovered without PCC) and PCC. Attention and executive function were measured with the Vienna Test System (Schuhfried®, Mödling, Austria). In verbal working memory, the PCC group had a significantly lower performance with a moderate effect. The rate of below-average performance was higher in PCC (56.2%) compared to no-C19 (20.6%) and C19 (15.8%). In divided attention and response inhibition, PCC also showed lower performance, 62.5% and 37.5%, respectively, than no-C19 and C19. The co-occurrence of decreased cognitive functions was pronounced in PCC. The present study revealed significant long-lasting cognitive dysfunction in PCC in young adults, two years after COVID-19 infection. Verbal working memory was significantly impaired, and a lower performance was found in divided attention and response inhibition. In addition, there was an increased reaction time in most cognitive tasks, demonstrating cognitive slowing in young people with PCC.

Elucidating SARS-CoV-2 neurotropism: a comprehensive Mendelian randomization study on cerebrospinal fluid biomarkers and their relevance to COVID-19 neurological manifestations

A mendelian randomization (MR) analysis was conducted to investigate whether SARS-CoV-2 invaded the human nervous system. This was confirmed by an increase in biomarkers found in the cerebrospinal fluid (CSF) and plasma of COVID-19 patients. To confirm the neuroinvasive properties of SARS-CoV-2, a series of analyses were conducted utilizing accessible datasets by MR. In addition, external validation was conducted by testing specific proteins in a retrospective cohort study, which included 40 COVID-19 patients with neurological complications and 15 disease controls (DC). Our investigation revealed the hospitalization, severity of COVID-19 increased the area and volume of certain brain regions, but no other significant causal effects were found of brain imaging-derived phenotypes (IDPs) on COVID-19. Notably, the COVID-19 hospitalization significantly increased the area and volume of the left caudal middle frontal gyrus (p_fdr = 0.012; p_fdr = 0.012, respectively). Additionally, COVID-19 severity was linked to the area, volume of the right caudal anterior-cingulate cortex and the volume of the right cuneus cortex (p_fdr = 0.023; p_fdr = 0.025; p_fdr = 0.026, respectively). In the CSF of COVID-19 patients, the median level of CHI3L1 was significantly higher (13677 pg/mL) compared to the DC group (8421 pg/mL, p < 1.00E-04). Similar trends were also found in CSF KLK6 and NGF-β. Additionally, the median NRGN level in plasma was significantly higher in the COVID-19 group (1013.00 pg/mL) compared to the control group (360.00 pg/mL, p = 6.50E-03). A subgroup analysis demonstrated that COVID-19 patients experiencing moderate to critical symptoms exhibited higher levels of GFAP in their CSF compared to those without. Elevated CSF levels of GFAP and S100B were also found in COVID-19 patients with decreased consciousness and comorbidities. This MR analysis provided evidence that SARS-CoV-2 may invade the human nervous system, as indicated by the increased levels of CSF biomarkers CHI3L1, NGF-β, and KLK6 in COVID-19 patients. These findings suggested that neuroinflammation could be a potential mechanism underlying the neurological complications seen in COVID-19 patients.

Dynamic brain glymphatic changes and cognitive function in COVID-19 recovered patients: a DTI-ALPS prospective cohort study

Objective

This study aimed to evaluate brain glymphatic function in COVID-19 recovered patients using the non-invasive Diffusion Tensor Imaging-Analysis Along the Perivascular Space (DTI-ALPS) technique. The DTI-ALPS technique was employed to investigate changes in brain glymphatic function in these patients and explore correlations with cognitive function and fatigue.

Materials and methods

Follow-up assessments were conducted at 1, 3, and 12 months post-recovery. A total of 31 patients completed follow-ups at all three time points, with 30 healthy controls (HCs) for comparison.

Results

Compared to HCs, COVID-19 recovered patients showed a significant decline in MoCA scores at 3 months post-recovery (p < 0.05), which returned to near-normal levels by 12 months. Mental fatigue, measured by the Fatigue Assessment Scale (FAS), was significantly higher in COVID-19 patients at all follow-up points compared to HCs (p < 0.05). The DTI-ALPS index in both hemispheres showed significant differences at 3 months post-recovery compared to HCs (p < 0.001), indicating increased glymphatic activity. Longitudinal analysis revealed a peak in the DTI-ALPS index at 3 months post-recovery, which then decreased by 12 months. Correlation analysis showed a significant negative correlation between the Bilateral brain hemisphere DTI-ALPS index and MoCA scores (right side: r = -0.373, p = 0.003; left side: r = -0.255, p = 0.047), and a positive correlation with mental fatigue (right side: r = 0.275, p = 0.032; left side: r = 0.317, p = 0.013).

Conclusion

This study demonstrates dynamic changes in brain glymphatic function in COVID-19 recovered patients, with a peak in activity at 3 months post-recovery. These changes are associated with cognitive function and mental fatigue, suggesting potential targets for addressing neurological symptoms of long COVID. The non-invasive DTI-ALPS technique proves to be a valuable tool for assessing brain glymphatic function in this population.

Neuroimaging insights into lung disease-related brain changes: from structure to function

Lung diseases induce changes in brain structure and function, leading to a range of cognitive, emotional, and motor deficits. The concept of the lung-brain axis has been proposed through neuroanatomy, endocrine, and immune pathway, while a considerable number of studies also explored the existence of the lung-brain axis from a neuroimaging perspective. This survey summarizes studies exploring the relationship between lung disease and brain structure and function from neuroimaging perspective, particular in magnetic resonance imaging (MRI). We have collated existing lung diseases studies and categorized them into four types: chronic obstructive pulmonary disease (COPD), coronavirus disease 2019 (COVID-19), lung cancer and other lung diseases. The observed structural and functional changes in the brain and cognitive dysfunction induced by lung diseases are discussed. We also present distinct pattern of brain changes in various lung diseases. Neuroimaging changes in COPD are concentrated in the frontal lobes, including gray matter atrophy, white matter damage, and reduced perfusion. Patients with COVID-19 exhibit extensive microhemorrhages and neuroinflammation, brain regions functionally connected to the primary olfactory cortex show greater changes. For lung cancer patients, brain changes are mainly attributed to the neurotoxicity of radiotherapy and chemotherapy, with damage concentrated in subcortical structures, patients with cancer pain demonstrate hyperconnectivity in motor and visual networks. The survey also discusses the pathological mechanisms revealed in neuroimaging studies and clinical significance of current studies. Finally, we analyzed current limitations, mainly in terms of small sample size, non-standardized criteria, reliance on correlation analyses, lack of longitudinal studies, and absence of reliable biomarkers. We suggest future research directions should include leveraging artificial intelligence for biomarker development, conducting longitudinal and multicenter studies, and investigating the systemic effects of lung disease on the brain and neuromodulation strategies.

The association among individual gray matter volume of frontal-limbic circuitry, fatigue susceptibility, and comorbid neuropsychiatric symptoms following COVID-19

BACKGROUND

Fatigue is often accompanied by comorbid sleep disturbance and psychiatric distress following the COVID-19 infection. However, identifying individuals at risk for developing post-COVID fatigue remains challenging. This study aimed to identify the neurobiological markers underlying fatigue susceptibility and further investigate their effect on COVID-19-related neuropsychiatric symptoms.

METHODS

Individuals following a mild SARS-CoV-2 infection (COV+) underwent neuropsychiatric measurements (n = 335) and MRI scans (n = 271) within 1 month (baseline), and 191 (70.5 %) of the individuals were followed up 3 months after infection. Sixty-seven healthy controls (COV-) completed the same recruitment protocol.

RESULTS

Whole-brain voxel-wise analysis showed that gray matter volume (GMV) during the acute phase did not differ between the COV+ and COV- groups. GMV in the right dorsolateral prefrontal cortex (DLPFC) and left dorsal anterior cingulate cortex (dACC) were associated with fatigue severity only in the COV+ group at baseline, which were assigned to the frontal system and limbic system, respectively. Furthermore, fatigue mediated the associations between volume differences in fatigue susceptibility and COVID-related sleep, post-traumatic stress disorder, anxiety and depression. Crucially, the initial GMV in the right DLPFC can predict fatigue symptoms 3 months after infection.

CONCLUSIONS

We provide novel evidence on the neuroanatomical basis of fatigue vulnerability and emphasize that acute fatigue is an important link between early GMV in the frontal-limbic regions and comorbid neuropsychiatric symptoms at baseline and 3 months after infection. Our findings highlight the role of the frontal-limbic system in predisposing individuals to develop post-COVID fatigue.

A multimodal neuroimaging meta-analysis of functional and structural brain abnormalities in attention-deficit/hyperactivity disorder

BACKGROUND

Numerous neuroimaging studies utilizing resting-state functional imaging and voxel-based morphometry (VBM) have identified variations in distinct brain regions among individuals with attention-deficit/hyperactivity disorder (ADHD). However, the results have been inconsistent.

METHODS

A comprehensive voxel-wise meta-analysis was performed on studies employing resting-state functional imaging and gray matter volume (GMV), examining discrepancies between individuals with ADHD and neurotypical controls (NCs). The analysis utilized the Seed-based d Mapping software.

RESULTS

A systematic review of the literature identified 21 functional imaging studies (595 ADHD and 564 controls) and 50 GMV studies (1907 ADHD and 1611 controls). In general, individuals with ADHD exhibited increased resting-state functional activity in the right parahippocampal gyrus and bilateral orbitofrontal cortex (OFC), as well as decreased resting-state functional activity in the bilateral cingulate cortex (including the posterior cingulate cortex [PCC], median cingulate cortex [MCC], and anterior cingulate cortex [ACC]). The VBM meta-analysis revealed decreased GMV in the bilateral OFC, right putamen (extending to right superior temporal gyrus [STG]), left inferior frontal gyrus (IFG), right superior frontal gyrus (SFG), ACC, and precentral gyrus among individuals with ADHD.

CONCLUSIONS

The multimodal meta-analyses indicated that individuals with ADHD exhibit abnormalities in both function and structure in the bilateral OFC. In addition, a few regions exhibited only functional or only structural abnormalities in ADHD, such as in the limbic, prefrontal, primary sensorimotor regions.

Myelin oligodendrocyte glycoprotein-associated transverse myelitis after SARS-CoV-2 infection: A case report

BACKGROUND

Cases of myelin oligodendrocyte glycoprotein (MOG) antibody-related disease have a history of coronavirus disease 2019 infection or its vaccination before disease onset. Severe acute respiratory syndrome virus 2 (SARS-CoV-2) infection has been considered to be a trigger of central nervous system autoimmune diseases.

CASE SUMMARY

Here we report a 20-year male with MOG-associated transverse myelitis after a SARS-CoV-2 infection. The patient received a near-complete recovery after standard immunological treatments.

CONCLUSION

Attention should be paid to the evaluation of typical or atypical neurological symptoms that may be triggered by SARS-CoV-2 infection.