Neuropsychological, medical and psychiatric findings after recovery from acute COVID-19: A cross-sectional study

Immune activation and immune-associated neurotoxicity in Long-COVID: A systematic review and meta-analysis of 103 studies comprising 58 cytokines/chemokines/growth factors

BACKGROUND

Multiple studies have shown that Long COVID (LC) disease is associated with heightened immune activation, as evidenced by elevated levels of inflammatory mediators. However, there is no comprehensive meta-analysis focusing on activation of the immune inflammatory response system (IRS) and the compensatory immunoregulatory system (CIRS) along with other immune phenotypes in LC patients.

OBJECTIVES

This meta-analysis is designed to explore the IRS and CIRS profiles in LC patients, the individual cytokines, chemokines, growth factors, along with C-reactive protein (CRP) and immune-associated neurotoxicity.

METHODS

To gather relevant studies for our research, we conducted a thorough search using databases such as PubMed, Google Scholar, and SciFinder, covering all available literature up to July 5th, 2024.

RESULTS

The current meta-analysis encompassed 103 studies that examined multiple immune profiles, C-reactive protein, and 58 cytokines/chemokines/growth factors in 5502 LC patients versus 5962 normal controls (NC). LC patients showed significant increases in IRS/CIRS ratio (standardized mean difference (SMD: 0.156, confidence interval (CI): 0.062;0.250), IRS (SMD: 0.338, CI: 0.236;0.440), M1 macrophage (SMD: 0.371, CI: 0.263;0.480), T helper (Th)1 (SMD: 0.316, CI: 0.185;0.446), Th17 (SMD: 0.439, CI: 0.302;0.577) and immune-associated neurotoxicity (SMD: 0.384, CI: 0.271;0.497). In addition, CRP and 21 different cytokines displayed significantly elevated levels in LC patients compared to NC.

CONCLUSION

LC disease is characterized by IRS activation and increased immune-associated neurotoxicity.

Memory complaints after COVID-19: a potential indicator of primary cognitive impairment or a correlate of psychiatric symptoms?

Cognitive impairment and symptoms of psychiatric disorders have been reported frequently as features of post-acute sequelae of SARS-CoV-2 infection. This study aims to investigate subjective memory complaints in COVID-19 survivors and determine if these are more strongly associated with objective cognitive impairment related to sequelae of SARS-CoV-2 infection or with symptoms of psychiatric conditions. A total of 608 COVID-19 survivors were evaluated in-person 6-11 months after hospitalization, with 377 patients assigned to a "no subjective memory complaint (SMC)" group and 231 patients assigned to an SMC group based on their Memory Complaint Scale scores. Follow-up evaluations included an objective cognitive battery and scale-based assessments of anxiety, depression, and post-traumatic stress symptoms. We found the perception of memory impairment in COVID-19 survivors to be more strongly associated to core symptoms of psychiatric conditions rather than to primary objective cognitive impairment. Univariate analysis indicated significant differences between the "no SMC" and SMC groups, both for the psychiatric symptom evaluations and for the cognitive evaluations (p < 0.05); however, the psychiatric symptoms all had large partial eta-squared values (ranging from 0.181 to 0.213), whereas the cognitive variables had small/medium partial eta-squared values (ranging from 0.002 to 0.024). Additionally, multiple regression analysis indicated that only female sex and depressive and post-traumatic stress symptoms were predictors of subjective memory complaints. These findings may help guide clinical evaluations for COVID-19 survivors presenting with memory complaints while also serving to expand our growing understanding of the relationship between COVID-19, subjective memory complaints, and the risk of cognitive decline.

Immune response and cognitive impairment in Post-COVID Syndrome: A systematic review

BACKGROUND

Altered immune response and cognitive difficulties have been demonstrated in studies of post-COVID syndrome, including differences in immune status and cognitive functioning in the months following infection. This review aimed to examine immune status and cognitive differences in post-COVID Syndrome twelve or more weeks after COVID-19 infection. A further aim of this review was to explore a link between immune response and the cognitive deficits observed in this group.

METHODS

A systematic review was carried out of PubMed, PsychInfo, EMBASE and Web of Science electronic databases of observational studies 12+ weeks after COVID-19 infection, with assessment of immune status and cognitive function in post-COVID Syndrome samples. This review protocol was recorded on PROSPERO with registration number CRD42022366920.

RESULTS

Following eligibility screening, eleven studies met inclusion criteria and were selected for our review. Six of eight studies which examined between group differences in specific domains suggested impaired cognition in the Post COVID Syndrome population, with the domains of executive function particularly affected. Of the eleven studies with immune data, nine studies reported increased markers of inflammation in the Post COVID Syndrome group, when compared to an age and gender matched "healthy control" sample, or population norms. Finally, when immune function and cognition are examined together, six studies presented results indicating a significant association between elevated immune response and cognitive function.

CONCLUSION

This review highlights the frequency of cognitive difficulties months after COVID-19 infection and explores heighted immune response as a predictor of this change. Six studies suggest that immune status is a predictor of cognitive function, examining a marker of immune function and objective cognitive performance at 12 or more weeks following infection. Future studies of cognitive function in Post COVID Syndrome are needed to explore this relationship, and underlying mechanisms leading to changes in cognitive performance.

Self-reported immune status and COVID-19 associated subjective cognitive functioning in post-COVID-19 syndrome: Examination of an Irish cohort

INTRODUCTION

Cognitive changes are very frequently reported by people with post-COVID-19 syndrome (PCS), but there is limited understanding of the underpinning mechanisms leading to these difficulties. It is possible that cognitive difficulties are related to immune status and/or low mood. The aim of the present study was to examine the relationship between immune status and cognitive functioning in PCS, while considering whether depression symptoms also influence this association.

METHODS

Participants were recruited in an online study of cognitive and psychological consequences of PCS, involving individuals attending a post-COVID clinic in an acute general hospital in Ireland, and a comparison sample of age- and sex-matched community controls who had also been infected with COVID-19 but had not experienced PCS. Participants with PCS (n = 71) and community controls (n = 50) completed the immune status questionnaire, Cognitive Failures Questionnaire (CFQ), Hospital Anxiety and Depression Scale (HADS), and the Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT-F).

RESULTS

Significant differences were observed between groups in terms of perceived immune status, perceived cognitive function, depression scores, and fatigue, with the "PCS" group reporting lower immune status, more cognitive difficulties, and higher levels of depression and fatigue. Regression analysis in the PCS group indicated that immune status and depression significantly contributed to variance in subjective cognitive functioning, with immune status remaining a significant predictor of cognitive functioning scores even when accounting for depression, fatigue, and other covariates related to PCS, such as Body Mass Index (BMI).

CONCLUSION

Our findings suggest that subjective cognitive functioning is influenced by self-reported immune status in PCS, emphasising the importance of immune status, cognitive, and mood screening as part of routine clinical care in PCS.

Medium- and Long-Term Effects of COVID-19 in a Population of Patients Admitted to the Intensive Care Unit: Cognitive and Psychological Sequelae and Quality of Life Six Months and One Year after Discharge

Most researchers have assessed cognitive functions in post-COVID-19 patients by means of screening tools and found cognitive sequelae in addition to anxiety, stress, depression, and a reduced quality of life (QoL). This study was aimed at investigating cognitive and psychological sequelae in patients admitted to the intensive care unit (ICU) six months (t6) and one year (t12) after discharge from the hospital, the impact of critical illness on well-being and QoL, and the protective role of cognitive reserve (CR). Twenty-three ICU patients underwent an extensive neuropsychological test battery at t6 and t12; a healthy control group underwent the same evaluation. Patient scores were compared with control scores: patients reported significantly lower scores in visual-spatial functions, both at t6 (U = 122; p = 0.033) and at t12 (U = 70; p = 0.003), and higher levels of anxiety (U = 126; p = 0.043) and depression (U = 97; p = 0.005) at t6; the levels of anxiety decreased at t12, while only depression symptoms persisted (U = 99.5; p = 0.025). Regarding the QoL, patients obtained lower scores in the physical component of QoL, both at t6 (U = 72; p = 0.008) and at t12 (U = 56.5; p = 0.005). Few and moderate correlations emerged between isolated cognitive functions and CR and the length of hospital stay. The results suggest a prevalent visual-spatial involvement, the medium- and long-term persistence of psychological sequelae, and a reduced QoL in ICU patients.

An immersive virtual reality-based object-location memory task reveals spatial long-term memory alterations in Long-COVID

Object-location memory (OLM) is a type of declarative memory for spatial information and consists of the individual's ability to establish accurate associations between objects and their spatial locations. Long-COVID describes the long-term effects of the COVID-19 disease. Long-COVID patients show medial temporal lobe dysfunction and neuropsychological alterations affecting memory. This study aimed to assess OLM in a group of Long-COVID patients, n=66, and a Control group of healthy individuals with similar age and sex composition, n=21, using an immersive virtual reality (iVR)-based OLM task. We also explored associations between the performance in the iVR-based OLM task and general cognitive function (MoCA), and both verbal (VSTM) and visuospatial (SSTM) span. The Long-COVID group showed fewer correct responses, made more task attempts, and invested more time in the iVR-based OLM task than the Control group. Delayed memory was more severely altered than immediate memory in Long-COVID participants. Better MoCA scores of the Long-COVID group were strongly associated with shorter times to complete the immediate recall of the iVR-based OLM task. Besides, the months elapsed since the COVID-19 infection were slightly associated with fewer correct responses in the immediate and 24-hour recalls. These results corroborate previous findings of memory alterations in the Long-COVID syndrome using an iVR-based OLM task, adding new evidence on spatial memory and long-term memory in this population. Implementing spatial iVR tasks to clinical research may improve our understanding of neuropsychological disorders.

Meta-analysis of Cognitive Function Following Non-severe SARS-CoV-2 Infection

To effectively diagnose and treat subjective cognitive symptoms in post-acute sequalae of COVID-19 (PASC), it is important to understand objective cognitive impairment across the range of acute COVID-19 severity. Despite the importance of this area of research, to our knowledge, there are no current meta-analyses of objective cognitive functioning following non-severe initial SARS-CoV-2 infection. The aim of this meta-analysis is to describe objective cognitive impairment in individuals with non-severe (mild or moderate) SARS-CoV-2 cases in the post-acute stage of infection. This meta-analysis was pre-registered with Prospero (CRD42021293124) and utilized the PRISMA checklist for reporting guidelines, with screening conducted by at least two independent reviewers for all aspects of the screening and data extraction process. Fifty-nine articles (total participants = 22,060) with three types of study designs met our full criteria. Individuals with non-severe (mild/moderate) initial SARS-CoV-2 infection demonstrated worse objective cognitive performance compared to healthy comparison participants. However, those with mild (nonhospitalized) initial SARS-CoV-2 infections had better objective cognitive performance than those with moderate (hospitalized but not requiring ICU care) or severe (hospitalized with ICU care) initial SARS-CoV-2 infections. For studies that used normative data comparisons instead of healthy comparison participants, there was a small and nearly significant effect when compared to normative data. There were high levels of heterogeneity (88.6 to 97.3%), likely reflecting small sample sizes and variations in primary study methodology. Individuals who have recovered from non-severe cases of SARS-CoV-2 infections may be at risk for cognitive decline or impairment and may benefit from cognitive health interventions.

Neurocognitive Impairment in Long COVID: A Systematic Review

OBJECTIVE

Although Coronavirus disease 2019 (COVID-19) is primarily a respiratory infectious disease, it has also been associated with a wide range of other clinical manifestations. It is widely accepted in the scientific community that many patients after recovery continue to experience COVID-19-related symptoms, including cognitive impairment. The aim of this systematic review was to investigate the cognitive profile of patients with long-COVID syndrome.

METHODS

A systematic search of empirical studies was conducted through the PubMed/Medline and Scopus electronic databases. Cross-sectional and longitudinal studies published between 2020 and 2023 were included.

RESULTS

Of the 516 studies assessed for eligibility, 36 studies met the inclusion criteria. All included studies support the presence of persistent cognitive changes after COVID-19 disease. Executive function, memory, attention, and processing speed appear to be the cognitive domains that are predominantly associated with long-COVID syndrome, whereas language is an area that has not been sufficiently investigated.

CONCLUSIONS

In this review, the high frequency of cognitive impairment after COVID-19 is evident. If we consider that cognitive functioning affects our ability to live independently and is a key determinant of our quality of life, it is imperative to precisely define those factors that may induce cognitive impairment in COVID-19 survivors, with the ultimate goal of early diagnosis of cognitive changes and, consequently, the development of targeted rehabilitation interventions to address them.

Long COVID in Brain Health Research: A Call to Action

The COVID-19 pandemic has brought attention to the long-term consequences of the virus, particularly the persistent symptoms that characterize long COVID. This syndrome, which can last for months after the initial infection, includes a range of neurological and neuropsychiatric manifestations that have significant implications for brain health and dementia research. This review explores the current understanding of long COVID's cognitive, neurological, and psychiatric symptoms and their potential impact on brain stimulation and neuroimaging studies. It argues that researchers must adapt their study designs and screening processes to account for the confounding effects of long COVID and ensure the accuracy and reliability of their findings. To advance the understanding of this condition and its long-term effects on brain health, the review proposes a series of strategies, including the development of standardized screening tools, the investigation of underlying mechanisms, and the identification of risk factors and protective factors. It also emphasizes the importance of collaborative research efforts and international data sharing platforms in accelerating the pace of discovery and developing targeted interventions for individuals with long COVID. As the prevalence of this condition continues to grow, it is imperative that the neuroscience community comes together to address this challenge and support those affected by long COVID.

Cognitive profile, neuroimaging and fluid biomarkers in post-acute COVID-19 syndrome

We aimed to characterize the cognitive profile of post-acute COVID-19 syndrome (PACS) patients with cognitive complaints, exploring the influence of biological and psychological factors. Participants with confirmed SARS-CoV-2 infection and cognitive complaints ≥ 8 weeks post-acute phase were included. A comprehensive neuropsychological battery (NPS) and health questionnaires were administered at inclusion and at 1, 3 and 6 months. Blood samples were collected at each visit, MRI scan at baseline and at 6 months, and, optionally, cerebrospinal fluid. Cognitive features were analyzed in relation to clinical, neuroimaging, and biochemical markers at inclusion and follow-up. Forty-nine participants, with a mean time from symptom onset of 10.4 months, showed attention-executive function (69%) and verbal memory (39%) impairment. Apathy (64%), moderate-severe anxiety (57%), and severe fatigue (35%) were prevalent. Visual memory (8%) correlated with total gray matter (GM) and subcortical GM volume. Neuronal damage and inflammation markers were within normal limits. Over time, cognitive test scores, depression, apathy, anxiety scores, MRI indexes, and fluid biomarkers remained stable, although fewer participants (50% vs. 75.5%; p = 0.012) exhibited abnormal cognitive evaluations at follow-up. Altered attention/executive and verbal memory, common in PACS, persisted in most subjects without association with structural abnormalities, elevated cytokines, or neuronal damage markers.

Change in Neuropsychological Test Performance Seen in a Longitudinal Study of Patients With Post-acute Sequelae of COVID-19: A 6-Month Follow-up Study

BACKGROUND

Post-acute sequelae of COVID-19 may include physical, psychiatric, and neurocognitive symptoms. Few studies of cognitive symptoms have been longitudinal, with many following participants briefly after infection and relying on subjective complaints, screening instruments, or computerized testing. This group previously reported diminished neuropsychological (NP) test performance in over half of 60 individuals tested in-person 7 months post-COVID-19, particularly those seeking care for cognitive complaints. The current study describes the initial and 6-month follow-up results of an expanded cohort of 75 participants.

OBJECTIVE

To measure longitudinal changes in neuropsychological test performance, as well as medical and psychiatric changes, post-COVID-19.

METHODS

Participants underwent NP, psychiatric, and medical assessments approximately 7 months after acute COVID-19 infection. Sixty-three (84%) returned approximately 6 months later for repeat evaluation.

RESULTS

At the initial visit, 29 (38.7%) met criteria for low NP performance, and 16 (21.3%) met criteria for extremely low NP performance. At 6-month follow-up, several NP domains that were significantly below normative values at the initial visit were no longer abnormal, with the exception of language. Only measures of delayed memory and fatigue showed significant improvements between the 2 time points.

CONCLUSIONS

A substantial proportion of individuals recovered from acute COVID-19 infection have persistent neuropsychiatric symptoms over 1 year after infection. While the overall sample in this study showed some improvement in NP test performance relative to norms, only fatigue and delayed memory improved significantly between times 1 and 2. No individual declined in NP test performance, though relatively few individuals made significant clinical improvement, indicating the need for serial neuropsychiatric assessment and treatment supports. Longitudinal follow-up of this cohort is in progress.

Neurocognitive Impairment in Post-COVID-19 Condition in Adults: Narrative Review of the Current Literature

The severe acute respiratory syndrome coronavirus 2 virus has, up to the time of this article, resulted in >770 million cases of COVID-19 illness worldwide, and approximately 7 million deaths, including >1.1 million in the United States. Although defined as a respiratory virus, early in the pandemic, it became apparent that considerable numbers of people recovering from COVID-19 illness experienced persistence or new onset of multi-system health problems, including neurologic and cognitive and behavioral health concerns. Persistent multi-system health problems are defined as Post-COVID-19 Condition (PCC), Post-Acute Sequelae of COVID-19, or Long COVID. A significant number of those with PCC report cognitive problems. This paper reviews the current state of scientific knowledge on persisting cognitive symptoms in adults following COVID-19 illness. A brief history is provided of the emergence of concerns about persisting cognitive problems following COVID-19 illness and the definition of PCC. Methodologic factors that complicate clear understanding of PCC are reviewed. The review then examines research on patterns of cognitive impairment that have been found, factors that may contribute to increased risk, behavioral health variables, and interventions being used to ameliorate persisting symptoms. Finally, recommendations are made about ways neuropsychologists can improve the quality of existing research.

Melatonin: a ferroptosis inhibitor with potential therapeutic efficacy for the post-COVID-19 trajectory of accelerated brain aging and neurodegeneration

The unprecedented pandemic of COVID-19 swept millions of lives in a short period, yet its menace continues among its survivors in the form of post-COVID syndrome. An exponentially growing number of COVID-19 survivors suffer from cognitive impairment, with compelling evidence of a trajectory of accelerated aging and neurodegeneration. The novel and enigmatic nature of this yet-to-unfold pathology demands extensive research seeking answers for both the molecular underpinnings and potential therapeutic targets. Ferroptosis, an iron-dependent cell death, is a strongly proposed underlying mechanism in post-COVID-19 aging and neurodegeneration discourse. COVID-19 incites neuroinflammation, iron dysregulation, reactive oxygen species (ROS) accumulation, antioxidant system repression, renin-angiotensin system (RAS) disruption, and clock gene alteration. These events pave the way for ferroptosis, which shows its signature in COVID-19, premature aging, and neurodegenerative disorders. In the search for a treatment, melatonin shines as a promising ferroptosis inhibitor with its repeatedly reported safety and tolerability. According to various studies, melatonin has proven efficacy in attenuating the severity of certain COVID-19 manifestations, validating its reputation as an anti-viral compound. Melatonin has well-documented anti-aging properties and combating neurodegenerative-related pathologies. Melatonin can block the leading events of ferroptosis since it is an efficient anti-inflammatory, iron chelator, antioxidant, angiotensin II antagonist, and clock gene regulator. Therefore, we propose ferroptosis as the culprit behind the post-COVID-19 trajectory of aging and neurodegeneration and melatonin, a well-fitting ferroptosis inhibitor, as a potential treatment.

Pathophysiological Mechanisms in Long COVID: A Mixed Method Systematic Review

INTRODUCTION

Long COVID (LC) is a global public health crisis affecting more than 70 million people. There is emerging evidence of different pathophysiological mechanisms driving the wide array of symptoms in LC. Understanding the relationships between mechanisms and symptoms helps in guiding clinical management and identifying potential treatment targets.

METHODS

This was a mixed-methods systematic review with two stages: Stage one (Review 1) included only existing systematic reviews (meta-review) and Stage two (Review 2) was a review of all primary studies. The search strategy involved Medline, Embase, Emcare, and CINAHL databases to identify studies that described symptoms and pathophysiological mechanisms with statistical analysis and/or discussion of plausible causal relationships between mechanisms and symptoms. Only studies that included a control arm for comparison were included. Studies were assessed for quality using the National Heart, Lung, and Blood Institute quality assessment tools.

RESULTS

19 systematic reviews were included in Review 1 and 46 primary studies in Review 2. Overall, the quality of reporting across the studies included in this second review was moderate to poor. The pathophysiological mechanisms with strong evidence were immune system dysregulation, cerebral hypoperfusion, and impaired gas transfer in the lungs. Other mechanisms with moderate to weak evidence were endothelial damage and hypercoagulation, mast cell activation, and auto-immunity to vascular receptors.

CONCLUSIONS

LC is a complex condition affecting multiple organs with diverse clinical presentations (or traits) underpinned by multiple pathophysiological mechanisms. A 'treatable trait' approach may help identify certain groups and target specific interventions. Future research must include understanding the response to intervention based on these mechanism-based traits.

[Interaction of somatic findings and psychiatric symptoms in COVID-19. A scoping review]

An infection with SARS-CoV‑2 can affect the central nervous system, leading to neurological as well as psychiatric symptoms. In this respect, mechanisms of inflammation seem to be of much greater importance than the virus itself. This paper deals with the possible contributions of organic changes to psychiatric symptomatology and deals especially with delirium, cognitive symptoms, depression, anxiety, posttraumatic stress disorder and psychosis. Processes of neuroinflammation with infection of capillary endothelial cells and activation of microglia and astrocytes releasing high amounts of cytokines seem to be of key importance in all kinds of disturbances. They can lead to damage in grey and white matter, impairment of cerebral metabolism and loss of connectivity. Such neuroimmunological processes have been described as a organic basis for many psychiatric disorders, as affective disorders, psychoses and dementia. As the activation of the glia cells can persist for a long time after the offending agent has been cleared, this can contribute to long term sequalae of the infection.

Pathophysiological, immunological, and inflammatory features of long COVID

The COVID-19 pandemic continues to cause severe global disruption, resulting in significant excess mortality, overwhelming healthcare systems, and imposing substantial social and economic burdens on nations. While most of the attention and therapeutic efforts have concentrated on the acute phase of the disease, a notable proportion of survivors experience persistent symptoms post-infection clearance. This diverse set of symptoms, loosely categorized as long COVID, presents a potential additional public health crisis. It is estimated that 1 in 5 COVID-19 survivors exhibit clinical manifestations consistent with long COVID. Despite this prevalence, the mechanisms and pathophysiology of long COVID remain poorly understood. Alarmingly, evidence suggests that a significant proportion of cases within this clinical condition develop debilitating or disabling symptoms. Hence, urgent priority should be given to further studies on this condition to equip global public health systems for its management. This review provides an overview of available information on this emerging clinical condition, focusing on the affected individuals' epidemiology, pathophysiological mechanisms, and immunological and inflammatory profiles.

Cognitive domains affected post-COVID-19; a systematic review and meta-analysis

BACKGROUND AND PURPOSE

This review aims to characterize the pattern of post-COVID-19 cognitive impairment, allowing better prediction of impact on daily function to inform clinical management and rehabilitation.

METHODS

A systematic review and meta-analysis of neurocognitive sequelae following COVID-19 was conducted, following PRISMA-S guidelines. Studies were included if they reported domain-specific cognitive assessment in patients with COVID-19 at >4 weeks post-infection. Studies were deemed high-quality if they had >40 participants, utilized healthy controls, had low attrition rates and mitigated for confounders.

RESULTS

Five of the seven primary Diagnostic and Statistical Manual of Mental Disorders (DSM-5) cognitive domains were assessed by enough high-quality studies to facilitate meta-analysis. Medium effect sizes indicating impairment in patients post-COVID-19 versus controls were seen across executive function (standardised mean difference (SMD) -0.45), learning and memory (SMD -0.55), complex attention (SMD -0.54) and language (SMD -0.54), with perceptual motor function appearing to be impacted to a greater degree (SMD -0.70). A narrative synthesis of the 56 low-quality studies also suggested no obvious pattern of impairment.

CONCLUSIONS

This review found moderate impairments across multiple domains of cognition in patients post-COVID-19, with no specific pattern. The reported literature was significantly heterogeneous, with a wide variety of cognitive tasks, small sample sizes and disparate initial disease severities limiting interpretability. The finding of consistent impairment across a range of cognitive tasks suggests broad, as opposed to domain-specific, brain dysfunction. Future studies should utilize a harmonized test battery to facilitate inter-study comparisons, whilst also accounting for the interactions between COVID-19, neurological sequelae and mental health, the interplay between which might explain cognitive impairment.

The global prevalence of depression, anxiety, and sleep disorder among patients coping with Post COVID-19 syndrome (long COVID): a systematic review and meta-analysis

BACKGROUND

Post COVID-19 syndrome, also known as "Long COVID," is a complex and multifaceted condition that affects individuals who have recovered from SARS-CoV-2 infection. This systematic review and meta-analysis aim to comprehensively assess the global prevalence of depression, anxiety, and sleep disorder in individuals coping with Post COVID-19 syndrome.

METHODS

A rigorous search of electronic databases was conducted to identify original studies until 24 January 2023. The inclusion criteria comprised studies employing previously validated assessment tools for depression, anxiety, and sleep disorders, reporting prevalence rates, and encompassing patients of all age groups and geographical regions for subgroup analysis Random effects model was utilized for the meta-analysis. Meta-regression analysis was done.

RESULTS

The pooled prevalence of depression and anxiety among patients coping with Post COVID-19 syndrome was estimated to be 23% (95% CI: 20%-26%; I2 = 99.9%) based on data from 143 studies with 7,782,124 participants and 132 studies with 9,320,687 participants, respectively. The pooled prevalence of sleep disorder among these patients, derived from 27 studies with 15,362 participants, was estimated to be 45% (95% CI: 37%-53%; I2 = 98.7%). Subgroup analyses based on geographical regions and assessment scales revealed significant variations in prevalence rates. Meta-regression analysis showed significant correlations between the prevalence and total sample size of studies, the age of participants, and the percentage of male participants. Publication bias was assessed using Doi plot visualization and the Peters test, revealing a potential source of publication bias for depression (p = 0.0085) and sleep disorder (p = 0.02). However, no evidence of publication bias was found for anxiety (p = 0.11).

CONCLUSION

This systematic review and meta-analysis demonstrate a considerable burden of mental health issues, including depression, anxiety, and sleep disorders, among individuals recovering from COVID-19. The findings emphasize the need for comprehensive mental health support and tailored interventions for patients experiencing persistent symptoms after COVID-19 recovery.

Cognition and psychological well-being in adults with post COVID-19 condition and analyses of symptom sequelae

OBJECTIVE

As the coronavirus disease 2019 (COVID-19) pandemic moves into its fourth year, gaining a better clinical understanding of individuals with post COVID-19 condition is paramount. The current study examined the neurocognitive and psychological status of adults with post COVID-19 condition, as well as explored the impact of high psychological burden on objective neurocognitive functioning and the relationship between subjective cognitive concerns and objective neurocognitive findings.

METHOD

Valid neuropsychological assessments were completed with 51 symptomatic adults who were 297.55 days, on average, following a confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Participants completed brief self-report depression, anxiety, and PTSD questionnaires, a questionnaire with subjective ratings of cognitive abilities, and standardized neurocognitive tests that examined performance validity, attention, processing speed, verbal learning and memory, naming, visual construction, and executive functioning.

RESULTS

The participants were mostly Caucasian (80.39%), middle-aged (average 47.37 years), women (82.35%), who were never hospitalized (86.27%). Despite all individuals reporting cognitive problems in daily life, mean performances on objective testing did not reveal any neurocognitive deficits (at or below the 8th percentile) at a group level. Approximately half (49.02%) of the participants reported co-occurring mental health symptoms that were considered clinically elevated based on questionnaire results. High psychological symptom burden was associated with greater subjective cognitive difficulties but did not result in neurocognitive dysfunction on objective testing.

CONCLUSIONS

This study contributes to the literature regarding post COVID-19 condition in adults including the relationship between the cognitive and psychological symptoms. Results are summarized in key clinical learning points.

"Brain Fog" After COVID-19 Infection: How the Field of Neuropsychology Can Help Clear the Air

The chapter explores the role of neuropsychology in understanding brain fog as a subjective complaint in the context of COVID-19. It discusses the historical and medical significance of the term "brain fog" and its psychological and neurological aspects. The chapter identifies the cognitive domains commonly affected by brain fog, such as attention, executive function, memory, and language. Additionally, it emphasizes the impact of societal changes during the COVID-19 pandemic on the general population as a crucial backdrop for understanding the issue. The chapter also highlights the important role of clinical and research neuropsychologists in gaining clarity on grouped data and individual patients' cognitive and emotional difficulties after COVID-19 infection. It discusses indications for neuropsychological rehabilitation and therapy and describes typical therapy phases and methods, including new approaches like telemedicine, virtual reality, and mobile app-based rehabilitation and self-tracking. The chapter underscores that experiences of brain fog can vary among COVID-19 patients and may change over time. It provides clinicians and interested parties with an in-depth understanding of brain fog and its manifestations, concomitant subtypes, and concrete strategies for addressing it. The chapter emphasizes the critical role of neuropsychology in scientifically examining brain fog and advocating for personalized approaches to cognitive rehabilitation.

Frequency, Characteristics, and Correlates of Cognitive Complaints in a Cohort of Individuals with Post-Acute Sequelae of COVID-19

BACKGROUND

Cognitive complaints are among the most frequent symptoms of post-acute sequelae of COVID-19 (PASC). This study aimed to investigate the frequency, characteristics, and clinical correlates of cognitive complaints (CC) in PASC, particularly in relation to objective neuropsychological (NP) performance.

METHODS

Seventy-four participants underwent psychiatric, medical, and NP testing approximately 7 months after acute COVID-19. The Patient Assessment of Own Functioning Inventory (PAOFI) was used to characterize the frequency and severity of CC in domains of memory, language, and cognitive/executive function. The associations of CC with sociodemographic, medical, psychiatric, and NP variables were assessed utilizing correlational analysis, logistic regression, and pairwise comparisons of those categorized as having CC vs. not having CC.

RESULTS

Taken together, approximately one-third of the study participants had clinically significant CC. Memory difficulty was the most frequent CC, although all categories were frequently endorsed. Memory and cognitive/executive complaints correlated with NP tests in these and multiple other NP domains. CC were more likely to be under-reported in those with diminished NP performance than over-reported in those without diminished performance. Acute COVID-19 symptom severity, elevated depressive symptoms, and NP tests of diminished attention and psychomotor processing speed were independent predictors of CC in logistic regression.

CONCLUSIONS

Cognitive complaints after acute COVID-19 should be taken seriously, as they are likely to reflect diminished NP performance, as well as medical, psychiatric, and functional burdens. However, patients with PASC may not accurately identify or characterize objective cognitive difficulties, so programs offering comprehensive care for patients with PASC should offer formal neuropsychological testing.

Neuropsychological Profile of Hospitalized Patients Due to COVID-19: Clinical and Inflammatory Correlates

OBJECTIVES

In the present study, we investigated the pattern of cognitive difficulties in hospitalized patients due to COVID-19 and its relation with the clinical features of the disease.

METHOD

Forty hospitalized patients with COVID-19 [mean age: 46.98 years (SD = 9.30); mean years of education: 13.65 (SD = 2.07) and 40 sex-, age- and education-matched healthy controls completed a set of neuropsychological measures administered by telephone. Participants' premorbid intellectual skills and patients' anxiety and depressive symptoms were also evaluated. The association of COVID-19-related biomarkers [oxygen saturation (SpO2), C-reactive protein (CRP), D-dimer and ferritin levels] with neuropsychological performances was examined with a series of hierarchical multiple linear regression analyses, after controlling for demographic and clinical characteristics, psychological distress and premorbid intellectual skills.

RESULTS

Patients performed worse than healthy participants on measures of verbal memory, attention and working memory. SpO2 levels were associated with patients' performance on verbal and working memory, whereas CRP levels were associated with performance on verbal memory, abstract reasoning and verbal fluency, after controlling for demographic and clinical characteristics. Ferritin levels predicted performance on the verbal fluency test, whereas D-dimer levels did not predict any of the neuropsychological measures.

CONCLUSIONS

Cognitive difficulties in verbal memory, attention and working memory were noted in patients with COVID-19. Markers of hyperinflammation predicted patients' performance above and beyond demographic characteristics, duration of symptoms, length of hospitalization and psychological distress.

Post-COVID-19 depression and serum interleukin 6 levels: A systematic review and meta-analysis of COVID-19 convalescents with and without depression

OBJECTIVES

Depression is among the psychiatric sequelae of COVID-19, affecting more than 20% of the convalescents. Its underlying pathophysiology remains unclear. Interleukin 6 (IL-6), a pro-inflammatory cytokine, plays a critical role in the COVID-19-associated cytokine storm, has been implicated in depressive disorders, and may thus be involved in post-COVID-19 depression.

METHODS

PubMed, Scopus, Embase, and Web of Science were systematically searched for relevant studies assessing peripheral IL-6 levels in convalescents who developed depression after COVID-19 vs. convalescents who did not.

RESULTS

Five studies were included in our systematic review, and four entered the meta-analysis. The meta-analysis revealed that post-COVID people with de novo depression did not have statistically significant differences in IL-6 levels compared to those without depression (standardised mean difference (SMD) = 0.09, 95% confidence interval (CI) = -0.35, 0.54, p-value = 0.68).

CONCLUSIONS

Although convalescents with depression did not have significantly higher IL-6 levels than convalescents without depression, the results should be interpreted considering the limited sample size and the low power of the included studies.

Effects of COVID-19 on cognition and brain health

COVID-19 is associated with a range of neurological, cognitive, and mental health symptoms both acutely and chronically that can persist for many months after infection in people with long-COVID syndrome. Investigations of cognitive function and neuroimaging have begun to elucidate the nature of some of these symptoms. They reveal that, although cognitive deficits may be related to brain imaging abnormalities in some people, symptoms can also occur in the absence of objective cognitive deficits or neuroimaging changes. Furthermore, cognitive impairment may be detected even in asymptomatic individuals. We consider the evidence regarding symptoms, cognitive deficits, and neuroimaging, as well as their possible underlying mechanisms.

Frequency and Characteristics of Depression and Its Association with Diminished Quality of Life in a Cohort of Individuals with Post-Acute Sequelae of COVID-19

Background

Approximately one-third of COVID-19 survivors will experience persistent symptoms, which may include neurological and psychiatric disturbances. Previous research has suggested that up to 45% of people develop clinically significant depressive symptoms post-COVID. This study sought to determine frequency, symptom profile, and clinical correlates of depression post-COVID.

Methods

Seventy-five participants who had recovered from COVID-19 underwent neurocognitive, psychiatric, medical, and cognitive testing/screening. The primary measures of interest in this report included the Patient Health Questionnaire (PHQ-9), a 9-item depression-screening tool, and the Endicott Quality of Life Enjoyment and Satisfaction Questionnaire.

Results

One-third of study participants screened as positive on the PHQ-9 for clinically significant depression, with the most commonly reported symptom being fatigue, followed by sleep disturbance and poor concentration. Also reported were decreased satisfaction in employment, sexual life, and mood. Depressed patients described greater illness severity during COVID-19 infection and subjective cognitive impairment, which was not found on neurocognitive testing. The only significant predictor of depression was COVID-19 illness severity.

Limitations

A significant portion of participants was a clinical population with specific post-COVID complaints and was predominately comprised of white females. Formal psychiatric evaluation was not performed.

Conclusion

Many individuals may experience depression after COVID-19 infection, with symptoms appearing to be predominately somatic in nature and correspond with COVID-19 illness severity.

Impact of COVID-19 on employment: sociodemographic, medical, psychiatric and neuropsychological correlates

Introduction

Given the nature of the persistent physical and neuropsychiatric symptoms reported in the literature, among individuals after acute COVID illness; there is growing concern about the functional implications of the Post-Acute Sequelae of COVID-19 (PASC). We aim to evaluate associations of sociodemographic, medical, psychiatric and neuropsychological factors with employment status post COVID-19.

Methods

59 participants were administered a neuropsychiatric assessment and queried about employment status and occupational difficulties months after quarantine. Two levels of comparison were conducted: (1) Those who took time off work (TTO) to those with no time off (NTO); (2) Those who reported occupational performance suffered (PS) to those who did not (PDNS).

Results

TTO vs. NTO exhibited extensive differences across medical, psychiatric and neurocognitive domains. PS vs. PDNS differed on subjective measures of physical and cognitive symptoms, but not on objective testing.

Conclusion

Individuals who took time off beyond COVID-19 quarantine experience persistent physical, psychiatric, subjective and objective neurocognitive burden. In contrast, occupational impairment appears to reflect subjective complaints, but not objective measures. Clinical implications are discussed.

Risk factors for post-COVID cognitive dysfunctions: the impact of psychosocial vulnerability

BACKGROUND

Cognitive dysfunction is a well-established manifestation of the post-COVID syndrome. Psychological vulnerability to stressors can modify disease trajectories, causing long-term risk for negative outcomes. Nonetheless, how premorbid risk factors and response to stressor affect neuropsychological changes is still incompletely understood. In this study, we explored the impact of psychosocial variables on cognitive functioning in a post-COVID sample.

METHODS

All subjects were submitted to a comprehensive neuropsychological battery and an assessment of perceived loneliness, post-traumatic stress, and changes in anxiety and depression levels. A social vulnerability index was also calculated. The set of psycho-social variables was reduced to two Principal Component Analysis (PCA) components: distress and isolation.

RESULTS

Forty-five percent of individuals showed cognitive impairments, with predominant memory and executive deficits. Post-traumatic stress disorder was clinically relevant in 44% of the sample. Social vulnerability scores of the sample were comparable to those of general population. The individual performance in learning and response initiation/suppression was directly related to distress component, encasing anxiety, stress, and depression measures.

CONCLUSION

These findings suggest that psychosocial assessment of post-COVID patients can detect fragile individuals at risk of cognitive impairments. Dedicated psychological support services may play a useful role in the prevention of post-COVID cognitive dysfunction.

Brain correlates of subjective cognitive complaints in COVID-19 survivors: A multimodal magnetic resonance imaging study

Cognitive impairment represents a leading residual symptom of COVID-19 infection, which lasts for months after the virus clearance. Up-to-date scientific reports documented a wide spectrum of brain changes in COVID-19 survivors following the illness's resolution, mainly related to neurological and neuropsychiatric consequences. Preliminary insights suggest abnormal brain metabolism, microstructure, and functionality as neural under-layer of post-acute cognitive dysfunction. While previous works focused on brain correlates of impaired cognition as objectively assessed, herein we investigated long-term neural correlates of subjective cognitive decline in a sample of 58 COVID-19 survivors with a multimodal imaging approach. Diffusion Tensor Imaging (DTI) analyses revealed widespread white matter disruption in the sub-group of cognitive complainers compared to the non-complainer one, as indexed by increased axial, radial, and mean diffusivity in several commissural, projection and associative fibres. Likewise, the Multivoxel Pattern Connectivity analysis (MVPA) revealed highly discriminant patterns of functional connectivity in resting-state among the two groups in the right frontal pole and in the middle temporal gyrus, suggestive of inefficient dynamic modulation of frontal brain activity and possible metacognitive dysfunction at rest. Beyond COVID-19 actual pathophysiological brain processes, our findings point toward brain connectome disruption conceivably translating into clinical post-COVID cognitive symptomatology. Our results could pave the way for a potential brain signature of cognitive complaints experienced by COVID-19 survivors, possibly leading to identify early therapeutic targets and thus mitigating its detrimental long-term impact on quality of life in the post-COVID-19 stages.

Biomarkers in long COVID-19: A systematic review

Purpose

Long COVID, also known as post-acute sequelae of COVID-19, refers to the constellation of long-term symptoms experienced by people suffering persistent symptoms for one or more months after SARS-CoV-2 infection. Blood biomarkers can be altered in long COVID patients; however, biomarkers associated with long COVID symptoms and their roles in disease progression remain undetermined. This study aims to systematically evaluate blood biomarkers that may act as indicators or therapeutic targets for long COVID.

Methods

A systematic literature review in PubMed, Embase, and CINAHL was performed on 18 August 2022. The search keywords long COVID-19 symptoms and biomarkers were used to filter out the eligible studies, which were then carefully evaluated.

Results

Identified from 28 studies and representing six biological classifications, 113 biomarkers were significantly associated with long COVID: (1) Cytokine/Chemokine (38, 33.6%); (2) Biochemical markers (24, 21.2%); (3) Vascular markers (20, 17.7%); (4) Neurological markers (6, 5.3%); (5) Acute phase protein (5, 4.4%); and (6) Others (20, 17.7%). Compared with healthy control or recovered patients without long COVID symptoms, 79 biomarkers were increased, 29 were decreased, and 5 required further determination in the long COVID patients. Of these, up-regulated Interleukin 6, C-reactive protein, and tumor necrosis factor alpha might serve as the potential diagnostic biomarkers for long COVID. Moreover, long COVID patients with neurological symptoms exhibited higher levels of neurofilament light chain and glial fibrillary acidic protein whereas those with pulmonary symptoms exhibited a higher level of transforming growth factor beta.

Conclusion

Long COVID patients present elevated inflammatory biomarkers after initial infection. Our study found significant associations between specific biomarkers and long COVID symptoms. Further investigations are warranted to identify a core set of blood biomarkers that can be used to diagnose and manage long COVID patients in clinical practice.

Anosmia in COVID-19 could be associated with long-term deficits in the consolidation of procedural and verbal declarative memories

Background and purpose

Long-COVID describes the long-term effects of the coronavirus disease 2019 (COVID-19). In long-COVID patients, neuropsychological alterations are frequently reported symptoms. Research points to medial temporal lobe dysfunction and its association with anosmia in long-COVID patients. This study aims to investigate the acquisition and consolidation of declarative and procedural memory in long-COVID patients and to explore whether anosmia is related to these dissociated memory functions.

Methods

Forty-two long-COVID participants and 30 controls (C) were recruited. The sample of long-COVID patients was divided into two groups based on the presence or absence of anosmia, group A and group NA, respectively. Objective performance in verbal declarative memory (Paired-Associate Learning, PAL), procedural memory (Mirror Tracing Test, MTT), general cognitive function (Montreal Cognitive Assessment scale), psychomotor speed, and incidental learning (Digit Symbol Substitution Test) were assessed and compared among the A, NA, and C groups. Long-term retention of PAL and MTT were assessed 24 h after acquisition.

Results

Lower scores in general cognition, psychomotor speed, and sustained attention were found in A and NA compared with C. However, incidental learning, both cue-guided and free-recalled, was diminished in group A compared with C, with no differences with group NA. General cognition and incidental learning were related to declarative memory function exclusively in long-COVID groups. Long-COVID groups presented lower long-term retention of verbal declarative memory than controls in recall tests but no differences in recognition tests. No group differences were found in the acquisition of procedural memory. However, long-term retention of this memory was worse in group A as compared to the NA and C groups, respectively, when errors and time of execution were considered.

Conclusion

Findings support that consolidation of both procedural and declarative memories is more affected than the acquisition of these memories in long-COVID patients, who are also more vulnerable to deficits in delayed recall than in recognition of declarative memories. Deficits in the consolidation of procedural memory and immediate recall of declarative information are especially relevant in long-COVID participants with anosmia. This indicates that anosmia in COVID-19 could be associated with a long-term dysfunction of the limbic system.

Cognitive dysfunction associated with COVID-19: Prognostic role of circulating biomarkers and microRNAs

COVID-19 is renowned as a multi-organ disease having subacute and long-term effects with a broad spectrum of clinical manifestations. The evolving scientific and clinical evidence demonstrates that the frequency of cognitive impairment after COVID-19 is high and it is crucial to explore more clinical research and implement proper diagnostic and treatment strategies. Several central nervous system complications have been reported as comorbidities of COVID-19. The changes in cognitive function associated with neurodegenerative diseases develop slowly over time and are only diagnosed at an already advanced stage of molecular pathology. Hence, understanding the common links between COVID-19 and neurodegenerative diseases will broaden our knowledge and help in strategizing prognostic and therapeutic approaches. The present review focuses on the diverse neurodegenerative changes associated with COVID-19 and will highlight the importance of major circulating biomarkers and microRNAs (miRNAs) associated with the disease progression and severity. The literature analysis showed that major proteins associated with central nervous system function, such as Glial fibrillary acidic protein, neurofilament light chain, p-tau 181, Ubiquitin C-terminal hydrolase L1, S100 calcium-binding protein B, Neuron-specific enolase and various inflammatory cytokines, were significantly altered in COVID-19 patients. Furthermore, among various miRNAs that are having pivotal roles in various neurodegenerative diseases, miR-146a, miR-155, Let-7b, miR-31, miR-16 and miR-21 have shown significant dysregulation in COVID-19 patients. Thus the review consolidates the important findings from the numerous studies to unravel the underlying mechanism of neurological sequelae in COVID-19 and the possible association of circulatory biomarkers, which may serve as prognostic predictors and therapeutic targets in future research.

Screening for brain fog: Is the montreal cognitive assessment an effective screening tool for neurocognitive complaints post-COVID-19?

BACKGROUND

Cognitive complaints are one of the most frequent symptoms reported in post-acute sequelae of COVID-19 (PASC). The Montreal Cognitive Assessment (MoCA) has been used to estimate prevalence of cognitive impairment in many studies of PASC, and is commonly employed as a screening test in this population, however, its validity has not been established.

OBJECTIVE

To determine the utility of the MoCA to screen for cognitive impairment in PASC.

METHODS

Sixty participants underwent neuropsychological, psychiatric, and medical assessments, as well as the Montreal Cognitive Assessment, 6-8 months after acute COVID-19 infection.

RESULTS

The overall sample had a mean score of 26.1 on the MoCA, with approximately one third screening below the cutoff score of 26, similar to the rate of extremely low NP test performance. MoCA score was inversely correlated with fatigue and depression measures and ethnic minority participants scored on average lower, despite similar education and estimated premorbid function. The MoCA had an accuracy of 63.3% at detecting any degree of diminished NP performance, and an accuracy of 73.3% at detecting extremely low NP performance.

DISCUSSION/CONCLUSION

The MoCA may not be accurate for detecting neither mild nor more severe degrees of diminished NP test performance in PASC. Therefore, patients with persistent cognitive complaints in the setting of PASC who score in the normal range on the MoCA should be referred for formal NP assessment.

Hypercoagulability, endotheliopathy, and inflammation approximating 1 year after recovery: Assessing the long-term outcomes in COVID-19 patients

Sustained hypercoagulability and endotheliopathy are present in convalescent COVID‐19 patients for up to 4 months from recovery. The hemostatic, endothelial, and inflammatory profiles of 39 recovered COVID‐19 patients were evaluated up to 16 months after recovery from COVID‐19. These values were compared with a control group of healthy volunteers (n = 124). 39 patients (71.8% males, median age 43 years) were reviewed at a mean of 12.7 ± 3.6 months following recovery. One patient without cardiovascular risk factors had post COVID‐19 acute ischaemic limb. Elevated D‐dimer and Factor VIII levels above normal ranges were noted in 17.9% (7/39) and 48.7% (19/39) of patients respectively, with a higher median D‐dimer 0.34 FEU μg/mL (IQR 0.28, 0.46) (p < .001) and Factor VIII 150% (IQR 171, 203) (p = .004), versus controls. Thrombin generation (Thromboscreen) showed a higher median endogenous thrombin potential (ETP) of 1352 nM*min (IQR 1152, 1490) (p = .002) and a higher median peak height of 221.4 nM (IQR 170.2, 280.4) (p = 0.01) and delayed lag time 2.4 min (1.42–2.97) (p = 0.0002) versus controls. Raised vWF:Ag and ICAM‐1 levels were observed in 17.9% (7/39) and 7.7% (3/39) of patients respectively, with a higher median VWF:Ag 117% (IQR 86, 154) (p = 0.02) and ICAM‐1 54.1 ng/mL (IQR 43.8, 64.1) (p = .004) than controls. IL‐6 was noted to be raised in 35.9% (14/39) of patients, with a higher median IL‐6 of 1.5 pg/mL (IQR 0.6, 3.0) (p = 0.004) versus controls. Subgroup analysis stratifying patients by COVID‐19 severity and COVID‐19 vaccination preceding SARS‐CoV‐2 infection did not show statistically significant differences. Hypercoagulability, endothelial dysfunction, and inflammation are still detectable in some patients approximately 1 year after recovery from COVID‐19.

Mild Cognitive Disorder in Post-COVID-19 Syndrome: A Retrospective Cohort Study of 67,000 Primary Care Post-COVID Patients

Background:

Little is known about the impact of COVID-19 on mild cognitive disorder.

Objective:

The aim of this retrospective cohort study was to investigate whether COVID-19 diagnosis is associated with subsequent mild cognitive disorder (MCD) compared to acute upper respiratory infections (AURI).

Methods:

This retrospective cohort study used data from the Disease Analyzer database (IQVIA) and included 67,046 patients with first-time symptomatic or asymptomatic COVID-19 diagnoses in 1,172 general practices in Germany between March 2020 and September 2021. Diagnoses were based on ICD-10 codes. Patients diagnosed with AURI were matched to 67,046 patients with COVID-19 using propensity scores based on sex, age, index month, and comorbidities. The index date was the diagnosis date for either COVID-19 or AURI. Associations between the COVID-19 and MCD were studied using conditional Poisson regression models.

Results:

The incidence of MCD was 7.6 cases per 1,000 person-years in the COVID-19 group and 5.1 cases per 1,000 person-years in the AURI group (IRR = 1.49, 95% CI = 1.22–1.82). The incidence rate ratio decreased strongly with increasing age from 10.08 (95% CI = 4.00–24.42) in the age group≤50 to 1.03 (95% CI = 0.81–1.31) in the age group > 70. In addition, the association between COVID-19 and MCD was significant in women (IRR: 1.70, 95% CI: 1.34–2.16) but not in men (IRR: 1.08, 95% CI: 0.75–1.56).

Conclusion

The incidence of MCD was low but significantly higher in COVID-19 than in AURI patients, especially among younger patients. If a cognitive disorder is suspected, referral to a specialist is recommended.

Neuropsychological Outcomes in Adult Patients and Survivors of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is believed to affect central nervous system functions through various indirect, and possibly direct, mechanisms. We are only now beginning to understand the possible effects of the virus on human cognition. This review summarizes extant yet limited literature on clinical neuropsychological findings in adult coronavirus disease 2019 (COVID-19) patients and survivors. Neuropsychological outcomes were often in the form of cognitive screen results, although various studies administered comprehensive batteries. With respect to screens, the Montreal Cognitive Assessment appeared relatively sensitive to cognitive dysfunction associated with COVID-19. Patients and survivors presented with weaknesses on screens and comprehensive batteries, although the pattern of these weaknesses was not specific to etiology. Broadly, weaknesses were suggestive of executive dysfunction, although more than one study did not detect significant impairment. Weaknesses should be interpreted cautiously due to potential confounds/contributing factors (weaknesses may partly reflect psychiatric sequelae; weaknesses may be over-interpreted due to inadequate assessment of premorbid functioning). Studies reported different approaches in defining impairment, likely contributing to variable findings. The current review discusses ongoing efforts to harmonize approaches to evaluating neuropsychological functioning globally, as well as emphasizes taking a comprehensive approach towards understanding how the disease affects cognition.