Tag: brain fog

Do Pre-existing Sleep Disorders Worsen Long COVID Fatigue and Brain Fog?

Abstract:

Introduction: Long COVID is common after COVID-19 infection and leads to functional limitations with most reporting substantial symptom burden from fatigue. Symptoms in sleep disorders are attributed to inflammatory dysregulation and may predispose to fatigue expression. We hypothesize prior diagnoses of sleep disorders are associated with severity of long COVID fatigue.
Methods: A retrospective EMR review was performed of 210 consecutive adult patients (9/2021 to 2/2022) referred at least 3 months after COVID-19 infection seen in a new community-based long COVID clinic. The intake process collected demographics, past medical history, functional questionnaires, and symptom checklists. Primary outcome was Fatigue Severity Scale (FSS) score. Sleep disorders were evaluated as a composite of self-reported insomnia, sleep disordered breathing, and restless legs syndrome as well as subset analyses of each disorder. Secondary outcome was physical functioning measured by ECOG performance scale. Linear analyses were used for FSS and ECOG analyses. Adjustors included age, sex, body mass index (BMI), and whether patient had COVID-19 hospitalization.
Results: Cohort was female (66.2%), aged 51.6±SD14.4 yrs, BMI 29.8 [IQR 26.2, 37.7]). Prior chronic insomnia was present in 9%, sleep disordered breathing in 23%, and RLS in 4%; the pooled history of sleep disorders was 30%. Fatigue was reported in 76% with mean FSS score of 5.44 [interquartile range, IQR: 4.11,6.44]; 48% reported brain fog. The interval between acute COVID infection and clinic evaluation was 10.4±5.34 months and had no association to FSS severity (r = 0.07, p = 0.30). Sleep disorders in aggregate, insomnia, and restless legs syndrome had no associations with fatigue or functional status. Sleep disordered breathing had an association to fatigue in unadjusted (β = 0.68, 95% confidence interval, [CI]:0.13,1.24), but not adjusted models (β = 0.53, 95%CI: -0.06,1.13). Sleep disorders both in aggregate and evaluated individually had no associations to brain fog.
Conclusion: A prior history of sleep disorders contributed little to post-COVID fatigue reported in those presenting to a community-based Long COVID clinic.

Source: Isabelle Carter and others, 0967 Do Pre-existing Sleep Disorders Worsen Long COVID Fatigue and Brain Fog?, Sleep, Volume 46, Issue Supplement_1, May 2023, Pages A426–A427, https://doi.org/10.1093/sleep/zsad077.0967 (Full text is available as PDF file)

Deficient GABABergic and glutamatergic excitability in the motor cortex of patients with long-COVID and cognitive impairment

Abstract:

Objective: Attention, working memory and executive processing have been reported to be consistently impaired in Neuro-Long coronavirus disease (COVID). On the hypothesis of abnormal cortical excitability, we investigated the functional state of inhibitory and excitatory cortical regulatory circuits by single “paired-pulse” transcranial magnetic stimulation (ppTMS) and Short-latency Afferent Inhibition (SAI).

Methods: We compared clinical and neurophysiological data of 18 Long COVID patients complaining of persistent cognitive impairment with 16 Healthy control (HC) subjects. Cognitive status was evaluated by means of the Montreal Cognitive Assessment (MoCA) and a neuropsychological evaluation of the executive function domain; fatigue was scored by the Fatigue Severity Scale (FSS). Resting motor threshold (RMT), the amplitude of the motor evoked potential (MEP), Short Intra-cortical Inhibition (SICI), Intra-cortical Facilitation (ICF), Long-interval Intracortical Inhibition (LICI) and Short-afferent inhibition (SAI) were investigated over the motor (M1) cortex.

Results: MoCA corrected scores were significantly different between the two groups (p = 0.023). The majority of the patients’ performed sub-optimally in the neuropsychological assessment of the executive functions. The majority (77.80%) of the patients reported high levels of perceived fatigue in the FSS. RMT, MEPs, SICI and SAI were not significantly different between the two groups. On the other hand, Long COVID patients showed a reduced amount of inhibition in LICI (p = 0.003) and a significant reduction in ICF (p < 0.001).

Conclusions: Neuro-Long COVID patients performing sub-optimally in the executive functions showed a reduction of LICI related to GABAb inhibition and a reduction of ICF related to glutamatergic regulation. No alteration in cholinergic circuits was found.

Significance: These findings can help to better understand the neurophysiological characteristics of Neuro-Long COVID, and in particular, motor cortex regulation in people with “brain fog”.

Source: Manganotti P, Michelutti M, Furlanis G, Deodato M, Buoite Stella A. Deficient GABABergic and glutamatergic excitability in the motor cortex of patients with long-COVID and cognitive impairment. Clin Neurophysiol. 2023 May 10;151:83-91. doi: 10.1016/j.clinph.2023.04.010. Epub ahead of print. PMID: 37210757; PMCID: PMC10170904. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10170904/ (Full text)

A review of cytokine-based pathophysiology of Long COVID symptoms

Abstract:

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production.

In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with “brain fog,” arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines.

There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Source: Low RN, Low RJ, Akrami A. A review of cytokine-based pathophysiology of Long COVID symptoms. Front Med (Lausanne). 2023 Mar 31;10:1011936. doi: 10.3389/fmed.2023.1011936. PMID: 37064029; PMCID: PMC10103649. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10103649/ (Full text)

Case Study: COVID-19 Brain Fog or Auditory Processing Disorder?

A wide array of symptoms have been directly associated with COVID-19 following recovery, but they can also occur several weeks or months after the diagnosis. These include, but are not limited to, damage to the respiratory tract as well as decreased cognition and other brain functions. The nonmedical term used to describe these post-COVID-19 problems is “brain fog.”

The symptoms of brain fog are similar to mild cognitive impairment or, of interest to audiologists, an auditory processing disorder (APD). 2 COVID-19 has neurological consequences and affects specific areas of the brain, such as the cingulate cortex (i.e. emotions, memory, depression, and decision of action). 3 Brain fog is also associated with several symptoms related to hearing and communication, which can affect the accomplishment of routine daily tasks. Many of those can be mistaken for or coexist with APD symptoms. These include “difficulty attending or staying focused, difficulty concentrating, difficulty understanding or remembering instructions, language problems, short-term memory problems,” to mention a few. 2 However, what might appear as a brain fog case could be an undiagnosed or even a pre-existing APD issue. 2 Symptoms could include struggling to keep track of conversations, forgetfulness and memory issues, problems following directions, and several cognitive difficulties. 2

This report presents the case of a 31-year-old medical doctor who was diagnosed with COVID-19 in December 2020, and later identified with APD symptoms that are now commonly seen in post-COVID-19 brain fog patients. Auditory training following the Buffalo Model 4 resolved the patient’s chief complaints following 12 treatment sessions. This issue is one of many that could shed light on the great potential auditory training has in resolving brain fog complaints that overlap with what is commonly seen in APD patients, highlighting the concerns regarding COVID-19’s direct effects on auditory processing.

Source: Alexander, Angela Loucks AuD, MNZAS, CCC-A; DiSogra, Robert M. AuD; Abbas, Fatima BS; Braund, Stacey AuD, CCC-A; Spokes, Chelsea BSpHLSc, MClinAud. Case Study: COVID-19 Brain Fog or Auditory Processing Disorder?. The Hearing Journal 76(04):p 18,19,20,22,23,24, April 2023. | DOI: 10.1097/01.HJ.0000927332.17564.4e https://journals.lww.com/thehearingjournal/Fulltext/2023/04000/Case_Study__COVID_19_Brain_Fog_or_Auditory.2.aspx (Full text)

Neurocognitive and psychiatric symptoms following infection with COVID-19: Evidence from laboratory and population studies

Abstract:

Objective: The objective of the current investigation was to examine associations between symptomatic COVID-19 history, neurocognitive function, and psychiatric symptoms using cognitive task performance, functional brain imaging, and a prospective population survey.

Methods: Study 1 was a laboratory study conducted between 3 May 2022 and 16 Nov 2022 involving 120 fully vaccinated community dwelling adults between 18 and 84 years of age (Mage = 31.96 (SD = 20.71), 63.3% female). In this cross-sectional study we examined the association between symptomatic COVID-19 infection history and performance on three computer tasks assessing cognitive function (Flanker interference, delay discounting and simple reaction time) and measured oxygen saturation within the prefrontal cortex using functional near infrared spectroscopy (fNIRS). Study 2 was a 2-wave population survey undertaken between 28 September 2021 and 21 March 2022, examining the prospective relationship between symptomatic COVID-19 and self-reported symptoms of cognitive dysfunction, depressive symptoms, anxiety symptoms, and agitation at 6-month follow up. The sample (N = 2,002, M age = 37.0, SD = 10.4; 60.8% female) was collected using a quota process to ensure equal numbers of vaccinated and unvaccinated individuals. Structural equation modelling with latent variables was performed on the population-level data, evaluating the fit of the proposed mediational model of symptomatic COVID-19 to psychiatric symptoms through cognitive dysfunction.

Results: Findings from Study 1 revealed significant effects of symptomatic COVID-19 history on Flanker interference and delay discounting. Effects on flanker performance were significantly stronger among older adult women (effect: 9.603, SE = 4.452, t = 2.157, p = .033), and were accompanied by task-related changes cerebral oxygenation at the right superior frontal gyrus (F (1, 143.1) = 4.729, p = .031). Additionally, those with a symptomatic COVID-19 infection history showed evidence of amplified delay discounting (coefficient = 0.4554, SE = 0.2208, t = 2.0629, p = .041). In Study 2, baseline symptomatic COVID-19 history was associated with self-reported cognitive dysfunction and a latent variable reflecting psychiatric symptoms of anxiety, depression and agitation at follow-up. Mediational analyses revealed evidence of cognitive mediation of clinically significant psychiatric outcomes: depression (indirect effect = 0.077, SE = 0.026, p = .003) and generalized anxiety (indirect effect = 0.060, SE = 0.021, p = .004).

Conclusions: Converging findings from laboratory and population survey data support the conclusion that symptomatic COVID-19 infection is associated with task-related, functional imaging and self-reported indices of cognitive dysfunction as well as psychiatric symptoms. In some cases, these findings appear to be more amplified among women than men, and among older women than younger.

Source: Hall PA, Ayaz H, Meng G, Hudson A, Sakib MN, Quah ACK, Agar TK, Lee JA, Boudreau C, Fong GT. Neurocognitive and psychiatric symptoms following infection with COVID-19: Evidence from laboratory and population studies. Brain Behav Immun Health. 2023 Mar;28:100595. doi: 10.1016/j.bbih.2023.100595. Epub 2023 Jan 24. PMID: 36713476; PMCID: PMC9870612. https://www.sciencedirect.com/science/article/pii/S2666354623000091?via%3Dihub (Full study)

Neurologic manifestations of long COVID differ based on acute COVID-19 severity

Abstract:

Objective: To characterize neurologic manifestations in post-hospitalization Neuro-PASC (PNP) and non-hospitalized Neuro-PASC (NNP) patients.

Methods: Prospective study of the first 100 consecutive PNP and 500 NNP patients evaluated at a Neuro-COVID-19 clinic between 5/2020 and 8/2021.

Results: PNP were older than NNP patients (mean 53.9 vs 44.9 y; p < 0.0001) with a higher prevalence of pre-existing comorbidities. An average 6.8 months from onset, the main neurologic symptoms were “brain fog” (81.2%), headache (70.3%), and dizziness (49.5%) with only anosmia, dysgeusia and myalgias being more frequent in the NNP compared to the PNP group (59 vs 39%, 57.6 vs 39% and 50.4 vs 33%, all p < 0.003). Moreover, 85.8% of patients experienced fatigue. PNP more frequently had an abnormal neurologic exam than NNP patients (62.2 vs 37%, p < 0.0001). Both groups had impaired quality of life in cognitive, fatigue, sleep, anxiety, and depression domains. PNP patients performed worse on processing speed, attention, and working memory tasks than NNP patients (T-score 41.5 vs 55, 42.5 vs 47 and 45.5 vs 49, all p < 0.001) and a US normative population. NNP patients had lower results in attention task only. Subjective impression of cognitive ability correlated with cognitive test results in NNP but not in PNP patients.

Interpretation: PNP and NNP patients both experience persistent neurologic symptoms affecting their quality of life. However, they harbor significant differences in demographics, comorbidities, neurologic symptoms and findings, as well as pattern of cognitive dysfunction. Such differences suggest distinct etiologies of Neuro-PASC in these populations warranting targeted interventions.

Source: Perez Giraldo GS, Ali ST, Kang AK, Patel TR, Budhiraja S, Gaelen JI, Lank GK, Clark JR, Mukherjee S, Singer T, Venkatesh A, Orban ZS, Lim PH, Jimenez M, Miller J, Taylor C, Szymanski AL, Scarpelli J, Graham EL, Balabanov RD, Barcelo BE, Cahan JG, Ruckman K, Shepard AG, Slutzky MW, LaFaver K, Kumthekar PU, Shetty NK, Carroll KS, Ho SU, Lukas RV, Batra A, Liotta EM, Koralnik IJ. Neurologic manifestations of long COVID differ based on acute COVID-19 severity. Ann Neurol. 2023 Mar 26. doi: 10.1002/ana.26649. Epub ahead of print. PMID: 36966460. https://onlinelibrary.wiley.com/doi/abs/10.1002/ana.26649 (Full text available as PDF file)

 

Investigating brain cortical activity in patients with post-COVID-19 brain fog

Abstract:

Brain fog is a kind of mental problem, similar to chronic fatigue syndrome, and appears about 3 months after the infection with COVID-19 and lasts up to 9 months. The maximum magnitude of the third wave of COVID-19 in Poland was in April 2021.

The research referred here aimed at carrying out the investigation comprising the electrophysiological analysis of the patients who suffered from COVID-19 and had symptoms of brain fog (sub-cohort A), suffered from COVID-19 and did not have symptoms of brain fog (sub-cohort B), and the control group that had no COVID-19 and no symptoms (sub-cohort C). The aim of this article was to examine whether there are differences in the brain cortical activity of these three sub-cohorts and, if possible differentiate and classify them using the machine-learning tools. The dense array electroencephalographic amplifier with 256 electrodes was used for recordings.

The event-related potentials were chosen as we expected to find the differences in the patients’ responses to three different mental tasks arranged in the experiments commonly known in experimental psychology: face recognition, digit span, and task switching. These potentials were plotted for all three patients’ sub-cohorts and all three experiments. The cross-correlation method was used to find differences, and, in fact, such differences manifested themselves in the shape of event-related potentials on the cognitive electrodes.

The discussion of such differences will be presented; however, an explanation of such differences would require the recruitment of a much larger cohort. In the classification problem, the avalanche analysis for feature extractions from the resting state signal and linear discriminant analysis for classification were used. The differences between sub-cohorts in such signals were expected to be found. Machine-learning tools were used, as finding the differences with eyes seemed impossible. Indeed, the A&B vs. C, B&C vs. A, A vs. B, A vs. C, and B vs. C classification tasks were performed, and the efficiency of around 60-70% was achieved.

In future, probably there will be pandemics again due to the imbalance in the natural environment, resulting in the decreasing number of species, temperature increase, and climate change-generated migrations. The research can help to predict brain fog after the COVID-19 recovery and prepare the patients for better convalescence. Shortening the time of brain fog recovery will be beneficial not only for the patients but also for social conditions.

Source: Wojcik GM, Shriki O, Kwasniewicz L, Kawiak A, Ben-Horin Y, Furman S, Wróbel K, Bartosik B, Panas E. Investigating brain cortical activity in patients with post-COVID-19 brain fog. Front Neurosci. 2023 Feb 9;17:1019778. doi: 10.3389/fnins.2023.1019778. PMID: 36845422; PMCID: PMC9947499. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9947499/ (Full text)

A Prospect to Ameliorate Affective Symptoms and to Enhance Cognition in Long COVID Using Auricular Transcutaneous Vagus Nerve Stimulation

Abstract:

Long COVID, the postviral disorder caused by COVID-19, is expected to become one of the leading causes of disability in Europe. The cognitive consequences of long COVID have been described as “brain fog” and characterized by anxiety and depression, and by cognitive deficits. Long COVID is assumed to be a complex condition arising from multiple causes, including persistent brainstem dysfunction and disrupted vagal signaling.

We recommend the potential application of auricular transcutaneous vagus nerve stimulation (atVNS) as an ADD-ON instrument to compensate for the cognitive decline and to ameliorate affective symptoms caused by long COVID. This technique enhances vagal signaling by directly activating the nuclei in the brainstem, which are hypoactive in long COVID to enhance mood and to promote attention, memory, and cognitive control-factors affected by long COVID.

Considering that atVNS is a non-pharmacological intervention, its ADD-ON to standard pharmaceutical agents will be useful for non-responders, making of this method a suitable tool. Given that atVNS can be employed as an ecological momentary intervention (EMI), we outline the translational advantages of atVNS in the context of accelerating the cognitive and affective recovery from long COVID.

Source: Colzato LS, Elmers J, Beste C, Hommel B. A Prospect to Ameliorate Affective Symptoms and to Enhance Cognition in Long COVID Using Auricular Transcutaneous Vagus Nerve Stimulation. J Clin Med. 2023 Feb 2;12(3):1198. doi: 10.3390/jcm12031198. PMID: 36769845. https://www.mdpi.com/2077-0383/12/3/1198 (Full text)

Long Covid and Neurodegenerative Disease

Abstract:

Brain fog with compromised ability to concentrate has been the most frequent Long Covid (LC) complaint. This is due to an increased TGF beta/IFN gamma with consequently increased bradykinin (BKN), especially in Caucasian females. Brain and lung blood vessels “leak.” This same ratio is increased in Alzheimer’s disease (AD), but decreased in Parkinson’s disease (PD), because CD4+ and CD8+ T cells are differentially affected by the invading associated viruses, e.g., SARS CoV2, HIV, ….

In Covid-19 CD147 receptors on immune cells are critical in generating the increased TGF beta/IFN gamma and those on endothelial cells, platelets, and erythrocytes are critical to the abnormal microvascular blood flow. ACE2 receptors on pneumocytes and enterocytes enable pulmonary and GI entry, initiating gut dysbiosis.

Epigenetics, methylation, magnesium, vitamin D, the B vitamins, and antioxidants suggest that these issues can be surmounted. Biochemical, physiologic, and epidemiologic data are analyzed to answer these questions. An LC model is presented and discussed in the context of the most recent research. Suggestions to avoid these and other worrisome concerns are included. Other topics discussed include estrogen, the gut microbiome, type 2 diabetes (T2D), and homocysteine.

Source: Chambers, P. Long Covid and Neurodegenerative Disease. Preprints 2023, 2023020027 (doi: 10.20944/preprints202302.0027.v1) https://www.preprints.org/manuscript/202302.0027/v1 (Full text available as PDF file)

 

Long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): Potential neurophysiological biomarkers for these enigmatic entities

Since early in the pandemic, fatigue has been recognized as one of the most common persistent complaints in individuals infected with SARS-CoV-2, and constitutes one main symptom of the so-called long-COVID syndrome. The term fatigue refers to a sustained feeling of tiredness, which can be present at rest; it is not directly related to physical activity, but can be exacerbated disproportionally by exertion.

Survivors of other recent coronavirus outbreaks, such as severe acute respiratory syndrome (SARS) in 2002 and Middle East respiratory syndrome (MERS) in 2012 also developed chronic fatigue. These ‘post-infectious’ fatigue syndromes, including long-COVID, resemble myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a chronic disorder of unknown physiopathology characterized by fatigue, post-exertional malaise, chronic muscle or skeletal pain, and cognitive impairment (‘brain fog’).

Despite it being an extremely disabling symptom, the results of routine examinations are often normal in patients complaining of lingering fatigue, a phenomenon that has also led the medical-scientific community to view this condition with skepticism.

In physiology, fatigue is defined as a decrease in the maximal force-generating capacity of a muscle during exercise. It may result from peripheral processes distal to the neuromuscular junction and from central processes controlling the discharge rate of motoneurons.

Physical fatigue related to both central and peripheral nervous system dysfunction can be assessed with neurophysiological techniques including transcranial magnetic stimulation (TMS) of the motor cortex, electrical stimulation of nerve trunks or intramuscular nerve fibers, and electromyography (EMG) recordings.

In August 2021, the first study showing myopathic changes in quantitative EMG (qEMG) in long-COVID patients with musculoskeletal symptoms was published (). The same authors demonstrated myopathic qEMG features and histopathological changes in skeletal muscle biopsies in 16 patients with complaints of fatigue, myalgia, and/or weakness persisting for up to 14 months after mild to moderate COVID-19 (). The wide variety of histological changes in this study, including muscle fiber atrophy, mitochondrial changes, subsarcolemmal accumulation, inflammation, capillaries alteration, suggests that skeletal muscle may be a major target of SARS-CoV-2.

On the opposite side of the neuroaxis, dysfunction in the activity of the primary motor cortex and reduced corticomotor output may underlie fatigue.

The first TMS study on motor cortex physiology was conducted on 12 patients with long-term fatigue and ‘brain fog’ after severe COVID-19 (). It showed disruption of the physiological mechanism of post-contraction depression, i.e., the transient decrease in the amplitude of motor evoked potentials and prolongation of the cortical silent period after a fatiguing motor task, which depends on cortical inhibitory mechanisms and has the protective purpose of preventing muscle overload. Impairment of intracortical GABAergic activity, as indicated by disrupted long-interval intracortical inhibition, together with reduced excitability of the primary motor cortex was subsequently demonstrated in 67 patients with fatigue and cognitive difficulties after mild COVID-19 (). These patients also presented selective deficits in executive functions. Based on these findings, the authors proposed that fatigue depends on altered excitability and neurotransmission within the motor cortex at rest, and on abnormal reactivity to muscular exercise. In addition, reduced executive control may contribute to exacerbating poor physical performance and fatigue tolerance ().

These objective neurophysiological and histopathological findings showed for the first time that fatigue may due both to pathological processes in the muscle (the effector of the motor command) and/or at the site of motor command processing. The mechanisms of chronic dysfunction of neural and muscle cells may be sustained by inflammation or dysimmunity, triggered by SARS-COV-2 in predisposed individuals.

Immune-inflammatory and neuroendocrine mechanisms have also been implicated in ME/CFS. In particular, increased production of autoantibodies against CNS and autonomic nervous system targets, such as the ß2 adrenergic receptor (ß2AdR), have been documented (). As ß2AdR are important vasodilators, their functional disturbance may result in vasoconstriction and hypoxemia with chronic muscular and cerebral hypoperfusion.

The COVID-19 pandemic is likely to greatly increase the incidence of ME/CFS, so that the intense research on the pathophysiological mechanisms of fatigue in long-COVID can help to shed light on a poorly understood and underestimated syndrome.

Source: Versace V, Tankisi H. Long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): Potential neurophysiological biomarkers for these enigmatic entities. Clin Neurophysiol. 2023 Jan 13;147:58-59. doi: 10.1016/j.clinph.2023.01.001. Epub ahead of print. PMID: 36657309; PMCID: PMC9838078. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9838078/ (Full text)