In a recent study published within the journal Scientific Reports, researchers assess neuropsychological deficits amongst individuals with persistent symptoms of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Study: Neuropsychological deficits in patients with persistent COVID-19 symptoms: a scientific review and meta-analysis. Image Credit: Creative Cat Studio / Shutterstock.com

Background

The coronavirus disease 2019 (COVID-19) has been established as a multi-organ illness with varied presentations, including neurological manifestations akin to dizziness, headaches, hyposmia, hypogeusia, intracerebral bleeding, stroke, and encephalopathy.

Previous studies have reported neuropsychiatric alterations, akin to mood disorders, anxiety, confusion, delirium, and agitation in COVID-19 patients. Neuropsychological deficits observed amongst SARS-CoV-2-infected individuals include executive and visuospatial functions, abstraction ability, working memory, and orientation based on the Montreal Cognitive Assessment (MoCA) scores.

Cognitive impairments have also been reported in COVID-19, no matter disease severity, and may very well be as a consequence of the direct effects of SARS-CoV-2 on the central nervous system (CNS) or indirect CNS involvement and the associated multi-organ damage, generalized inflammation, hypoxia, or immunological dysregulation.

Importantly, these symptoms may persist beyond the acute phase of infection in a condition otherwise often known as ‘long COVID.’

Concerning the study

In the current meta-analysis, researchers examine the association between long COVID and neuropsychological symptoms following recovery from acute infection.

Data were searched within the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Web of Science, Scopus, PubMed, Google Scholar, and PsycINFO databases between January 2020 and September 2021. References to the included articles and narrative or systematic reviews were also analyzed. Data were screened by two independent researchers, and disagreements were solved by discussion or consulting one other researcher.

Random-effects modeling was performed to research the cognitive performance of post-COVID-19 patients and healthy individuals. The I² statistic was used to evaluate heterogeneity within the included studies. Sensitivity analyses were also performed to find out whether excluding individual studies could impact the outcomes.

Studies with confirmed COVID-19 patients diagnosed three weeks or more before study initiation were included within the evaluation. Those with COVID-19-related conditions within the post-acute phase of infection undergoing standardized cognitive functional assessments were included within the evaluation.

Moreover, studies with cohort, case-control, cross-sectional, case reports, case series, and quantitative-type study designs, in addition to letters and preprints describing original research comprising data on individuals with suspected or laboratory-confirmed COVID-19, were also evaluated.

Studies assessing cognitive defects without validated assessments and people investigating the indirect effects of SARS-CoV-2 infections on mental well-being amongst uninfected individuals mediated by social distancing measures, including quarantine and isolation and without SARS-CoV-2-positive polymerase chain response (PCR) results were excluded from the evaluation. All studies included within the meta-analysis had healthy control groups and reported global cognitive scores.

Conference presentation abstracts and studies comprising individuals with a history of pathologies that might impact cognitive function, including neurodegenerative illnesses, acquired brain damage, and neuropsychiatric disorders, were also excluded.

The standard of the included records was assessed using the Newcastle-Ottawa Scale (NOS). Bias risks were evaluated using the Risk of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool.

Long COVID increases risk of cognitive dysfunction

The initial search yielded 1,602 records, with citation searching providing a further 20 records. A complete of 338 duplicates were removed, whereas 978 records, including book chapters, guidelines, and protocols, were removed, after which 80 underwent full-text screening.

An extra 32 records that didn’t meet the eligibility criteria were removed, which included 14 records with inadequate data and nine opinion articles. Of the remaining 25 studies, six were considered for the meta-analysis.

The studies included within the meta-analysis comprised 175 COVID-19 convalescents and 275 healthy participants. Inside the control group, 55% were women with a mean age of 53, whereas the experimental group comprised 51% of ladies with an analogous mean age.

A medium-to-high effect size and a significantly moderate level of heterogeneity amongst studies, as demonstrated by I² of 63%, were observed. COVID-19 convalescents showed significant cognitive deficits as compared to controls. The sensitivity evaluation showed similar findings, thus indicating the robustness of the first evaluation findings.

Conclusions

The study findings display that cognitive dysfunction was more prevalent amongst individuals with persistent symptoms of SARS-CoV-2 infection as in comparison with healthy individuals. These observations contribute to existing scientific literature; nevertheless, the dearth of standardized protocols for cognitive evaluations at baseline might limit the accurate comparison of the outcomes of the included studies.

Importantly,  psychological, contextual, and socioeconomic aspects and the impact of cognitive reserve affected by COVID-19 weren’t considered. Collectively, these aspects may limit the power of scientists to tell apart between the results of infection on cognitive function and the general influence of the pandemic.

Further research must fastidiously assess long-term cognitive decline amongst individuals with persistent symptoms of COVID-19 and rehabilitation intervention efficacy.