Cognitive assessment in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a cognitive substudy of the multi-site clinical assessment of ME/CFS (MCAM)

Abstract:

Introduction: Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) experience cognitive problems with attention, information processing speed, working memory, learning efficiency, and executive function. Commonly, patients report worsening of cognitive symptoms over time after physical and/or cognitive challenges. To determine, monitor, and manage longitudinal decrements in cognitive function after such exposures, it is important to be able to screen for cognitive dysfunction and changes over time in clinic and also remotely at home. The primary objectives of this paper were: (1) to determine whether a brief computerized cognitive screening battery will detect differences in cognitive function between ME/CFS and Healthy Controls (HC), (2) to monitor the impact of a full-day study visit on cognitive function over time, and (3) to evaluate the impact of exercise testing on cognitive dysfunction.

Methods: This cognitive sub-study was conducted between 2013 and 2019 across seven U.S. ME/CFS clinics as part of the Multi-Site Clinical Assessment of ME/CFS (MCAM) study. The analysis included 426 participants (261 ME/CFS and 165 HC), who completed cognitive assessments including a computerized CogState Brief Screening Battery (CBSB) administered across five timepoints (T0-T4) at the start of and following a full day in-clinic visit that included exercise testing for a subset of participants (182 ME/CFS and 160 HC). Exercise testing consisted of ramped cycle ergometry to volitional exhaustion. The primary outcomes are performance accuracy and latency (performance speed) on the computerized CBSB administered online in clinic (T0 and T1) and at home (T2-T4).

Results: No difference was found in performance accuracy between ME/CFS and HCs whereas information processing speed was significantly slower for ME/CFS at most timepoints with Cohen’s d effect sizes ranging from 0.3-0.5 (p < 0.01). The cognitive decline over time on all CBSB tasks was similar for patients with ME/CFS independent of whether exercise testing was included in the clinic visit.

Conclusion: The challenges of a clinic visit (including cognitive testing) can lead to further cognitive deficits. A single short session of intense exercise does not further reduce speed of performance on any CBSB tasks.

Source: Lange G, Lin JS, Chen Y, Fall EA, Peterson DL, Bateman L, Lapp C, Podell RN, Natelson BH, Kogelnik AM, Klimas NG, Unger ER. Cognitive assessment in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS): a cognitive substudy of the multi-site clinical assessment of ME/CFS (MCAM). Front Neurosci. 2024 Nov 1;18:1460157. doi: 10.3389/fnins.2024.1460157. PMID: 39554847; PMCID: PMC11565701. https://pmc.ncbi.nlm.nih.gov/articles/PMC11565701/ (Full text)

Stroop task and practice effects demonstrate cognitive dysfunction in long COVID and myalgic encephalomyelitis / chronic fatigue syndrome

Abstract:

Background: The Stroop task was used to investigate differences in cognitive function between Long COVID (LC), Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) and healthy control subjects.

Methods: Subjects viewed four color words or neutral (XXXX) stimuli with the same (congruent) or different color ink (incongruent). Cognitive conflict was inferred from response times for pairings of prestimuli and subsequent stimuli. Overall effects were assessed by univariate analysis with time courses determined for binned response times.

Results: LC and ME/CFS had significantly longer response times than controls indicating cognitive dysfunction. Initial response times were ranked LC > ME > HC, and decreased according to power functions. At the end of the task (900s), times were ranked LC = ME > HC. Response times were significantly slower for stimuli following an incongruent prestimulus. Time series for Stroop effect, facilitation, interference, surprise index and practice power law parameters were generally similar in LC, ME/CFS and HC suggesting comparable patterns for recruitment of cognitive resources. The prestimulus data were analyzed and generated positive Stroop and interference effects that were distinct from stimulus effects.

Conclusion: LC and ME/CFS have global slowing of response times that cannot be overcome by practice suggesting impaired communications between network nodes during problem solving. Analysis of matched prestimulus – stimulus effects adds a new dimension for understanding cognitive conflict.

Brief summary: Cognitive dysfunction in Long COVID and ME/CFS was demonstrated using the Stroop task which found global slowing of response times and limitations of practice effects.

Source: Baraniuk JN, Thapaliya K, Inderyas M, Shan ZY, Barnden LR. Stroop task and practice effects demonstrate cognitive dysfunction in long COVID and myalgic encephalomyelitis / chronic fatigue syndrome. Sci Rep. 2024 Nov 5;14(1):26796. doi: 10.1038/s41598-024-75651-3. PMID: 39500939; PMCID: PMC11538523. https://pmc.ncbi.nlm.nih.gov/articles/PMC11538523/ (Full text)

Plasma Neurofilament Light Chain: A Potential Biomarker for Neurological Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disorder characterized by heterogeneous symptoms, which lack specific biomarkers for its diagnosis. This study aimed to investigate plasma neurofilament light chain (NfL) levels as a potential biomarker for ME/CFS and explore associations with cognitive, autonomic, and neuropathic symptoms.

Here, 67 ME/CFS patients and 43 healthy controls (HCs) underwent comprehensive assessments, including neuropsychological evaluation, autonomic nervous system (ANS) testing, and plasma NfL level analysis. ME/CFS patients exhibited significantly higher plasma NfL levels compared to HC (F = 4.30, p < 0.05). Correlations were observed between NfL levels and cognitive impairment, particularly in visuospatial perception (r = -0.42; p ≤ 0.001), verbal memory (r = -0.35, p ≤ 0.005), and visual memory (r = -0.26; p < 0.05) in ME/CFS. Additionally, higher NfL levels were associated with worsened autonomic dysfunction in these patients, specifically in parasympathetic function (F = 9.48, p ≤ 0.003).

In ME/CFS patients, NfL levels explained up to 17.2% of the results in cognitive tests. Unlike ME/CFS, in HC, NfL levels did not predict cognitive performance. Elevated plasma NfL levels in ME/CFS patients reflect neuroaxonal damage, contributing to cognitive dysfunction and autonomic impairment.

These findings support the potential role of NfL as a biomarker for neurological dysfunction in ME/CFS. Further research is warranted to elucidate underlying mechanisms and clinical implications.

Source: Azcue N, Tijero-Merino B, Acera M, Pérez-Garay R, Fernández-Valle T, Ayo-Mentxakatorre N, Ruiz-López M, Lafuente JV, Gómez Esteban JC, Del Pino R. Plasma Neurofilament Light Chain: A Potential Biomarker for Neurological Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Biomedicines. 2024 Jul 11;12(7):1539. doi: 10.3390/biomedicines12071539. PMID: 39062112; PMCID: PMC11274366. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11274366/ (Full text)

Examining well-being and cognitive function in people with long Covid and ME/CFS, and age-matched healthy controls: A Case-Case-Control Study

Abstract:

Purpose: Well-being and cognitive function had not previously been compared between people with long COVID and people with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Therefore, this study examined well-being and cognitive function in people with long COVID (∼16 months illness duration; n= 17) and ME/CFS (∼16 years illness duration; n=24), versus age-matched healthy controls (n=16).

Methods: Well-being was examined using several questionnaires, namely the Health Visual Analogue Scale (VAS), Fatigue Severity Scale (FSS), Post-exertional malaise (PEM), Pittsburgh Sleep Quality Index (PSQI), European Quality of Life-5 Domains (EQ-5D), MRC Dyspnoea, Self-Efficacy (SELTC), The Edinburgh Neurosymptoms Questionnaire (ENS), General Anxiety Disorder 7 (GAD-7), and Patient Health Questionnaire 9 (PHQ-9). Cognitive function was examined using Single Digit Modalities Test (SDMT), Stroop test, and Trails A and B. These were delivered via a mobile application (app) built specifically for this remote data collection.

Results: The main findings of the present investigation were that people with ME/CFS and people with long COVID were generally comparable on all well-being and cognitive function measures, but self-reported worse values for pain, fatigue, Post-exertional malaise, sleep quality, general well-being in relation to mobility, usual activities, self-care, breathlessness, neurological symptoms, self-efficacy, and other well-being such as anxiety and depression, compared to controls. There was no effect of group for cognitive function measures.

Conclusions: These data suggest that both people with long COVID and people with ME/CFS have similar impairment on well-being measures examined herein. Therefore, interventions that target well-being of people with ME/CFS and long COVID are required.

Source: Sanal-Hayes NEM, Mclaughlin M, Hayes LD, Berry ECJ, Sculthorpe NF. Examining well-being and cognitive function in people with long Covid and ME/CFS, and age-matched healthy controls: A Case-Case-Control Study. Am J Med. 2024 May 13:S0002-9343(24)00273-0. doi: 10.1016/j.amjmed.2024.04.041. Epub ahead of print. PMID: 38750713. https://www.amjmed.com/article/S0002-9343(24)00273-0/fulltext (Full text)

Cognitive profile in multiple sclerosis and post-COVID condition: a comparative study using a unified taxonomy

Abstract:

Post-COVID condition (PCC) and multiple sclerosis (MS) share some clinical and demographic features, including cognitive symptoms and fatigue. Some pathophysiological mechanisms well-known in MS, such as autoimmunity, neuroinflammation and myelin damage, have also been implicated in PCC. In this study, we aimed to compare the cognitive phenotypes of two large cohorts of patients with PCC and MS, and to evaluate the relationship between fatigue and cognitive performance.

Cross-sectional study including 218 patients with PCC and 218 with MS matched by age, sex, and years of education. Patients were evaluated with a comprehensive neuropsychological protocol and were categorized according to the International Classification of Cognitive Disorders system. Fatigue and depression were also assessed.

Cognitive profiles of PCC and MS largely overlapped, with a greater impairment in episodic memory in MS, but with small effect sizes. The most salient deficits in both disorders were in attention and processing speed. The severity of fatigue was greater in patients with PCC. Still, the correlations between fatigue severity and neuropsychological tests were more prominent in the case of MS. There were no differences in the severity of depression among groups. Our study found similar cognitive profiles in PCC and MS. Fatigue was more severe in PCC, but was more associated with cognitive performance in MS. Further comparative studies addressing the mechanisms related to cognitive dysfunction and fatigue may be of interest to advance the knowledge of these disorders and develop new therapies.

Source: Delgado-Alonso C, Delgado-Alvarez A, Díez-Cirarda M, Oliver-Mas S, Cuevas C, Montero-Escribano P, Ramos-Leví AM, Gil-Moreno MJ, López-Carbonero JI, Hermann BP, Matias-Guiu J, Matias-Guiu JA. Cognitive profile in multiple sclerosis and post-COVID condition: a comparative study using a unified taxonomy. Sci Rep. 2024 Apr 29;14(1):9806. doi: 10.1038/s41598-024-60368-0. PMID: 38684843; PMCID: PMC11059260. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11059260/ (Full text)

Phenylephrine Alters Phase Synchronization between Cerebral Blood Velocity and Blood Pressure in Chronic Fatigue Syndrome with Orthostatic Intolerance

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) with orthostatic intolerance (OI) is characterized by neuro-cognitive deficits perhaps related to upright hypocapnia and loss of cerebral autoregulation (CA). We performed N-back neurocognition testing and calculated the phase synchronization index (PhSI) between Arterial Pressure (AP) and cerebral blood velocity (CBV) as a time-dependent measurement of cerebral autoregulation in 11 control (mean age=24.1 years) and 15 ME/CFS patients (mean age=21.8 years). All ME/CFS patients had postural tachycardia syndrome (POTS).

A 10-minute 60⁰ head-up tilt (HUT) significantly increased heart rate (109.4 ± 3.9 vs. 77.2 ± 1.6 beats/min, P <0.05) and respiratory rate (20.9 ± 1.7 vs. 14.2 ± 1.2 breaths/min, P < 0.05) and decreased end-tidal CO2 (ETCO2; 33.9 ± 1.1 vs. 42.8 ± 1.2 Torr, P < 0.05) in ME/CFS vs. control. In ME/CFS, HUT significantly decreased CBV compared to control (-22.5% vs -8.7%, p<0.005).

To mitigate the orthostatic CBV reduction, we administered supplemental CO2, phenylephrine and acetazolamide and performed N-back testing supine and during HUT. Only phenylephrine corrected the orthostatic decrease in neurocognition by reverting % correct n=4 N-back during HUT in ME/CFS similar to control (ME/CFS=38.5±5.5 vs. ME/CFS+PE= 65.6±5.7 vs. Control 56.9±7.5). HUT in ME/CFS resulted in increased PhSI values indicating decreased CA. While CO2 and Acetazolamide had no effect on PhSI in ME/CFS, PE caused a significant reduction in PhSI (ME/CFS=0.80±0.03 vs ME/CFS+PE= 0.69±0.04, p< 0.05) and improved cerebral autoregulation. Thus, PE improved neurocognitive function in ME/CFS patients, perhaps related to improved neurovascular coupling, cerebral autoregulation and maintenance of CBV.

Source: Medow MS, Stewart JM. Phenylephrine Alters Phase Synchronization between Cerebral Blood Velocity and Blood Pressure in Chronic Fatigue Syndrome with Orthostatic Intolerance. Am J Physiol Regul Integr Comp Physiol. 2024 Apr 29. doi: 10.1152/ajpregu.00071.2024. Epub ahead of print. PMID: 38682242. https://journals.physiology.org/doi/abs/10.1152/ajpregu.00071.2024 (Full text available as PDF file)

Exploring Cognitive Dysfunction in Long COVID Patients: Eye Movement Abnormalities and Frontal-Subcortical Circuits Implications via Eye-Tracking and Machine Learning

Abstract:

Background: Cognitive dysfunction is regarded as one of the most severe aftereffects following coronavirus disease 2019 (COVID-19). Eye movements, controlled by various brain regions, including the dorsolateral prefrontal cortex and frontal-thalamic circuits, offer a potential metric for evaluating cognitive dysfunction. We aimed to examine the utility of eye movement measurements in identifying cognitive impairments in long COVID patients.

Methods: We recruited 40 long COVID patients experiencing subjective cognitive complaints and 40 healthy controls and used a certified eye-tracking medical device to record saccades and antisaccades. Machine learning was applied to enhance the analysis of eye movement data.

Results: Patients did not differ from the healthy controls regarding age, sex, and years of education. However, the patients’ Montreal Cognitive Assessment total score was significantly lower than healthy controls. Most eye movement parameters were significantly worse in patients: the latencies, gain, and velocity of visually and memory-guided saccades, the number of correct memory saccades, the latencies and duration of reflexive saccades, and the number of errors in the antisaccade test. Machine learning permitted distinguishing between long COVID patients experiencing subjective cognitive complaints and healthy controls.

Conclusion: Our findings suggest impairments in frontal subcortical circuits in long COVID patients experiencing subjective cognitive complaints. Eye-tracking, combined with machine learning, offers a novel, efficient way to assess and monitor long COVID patients’ cognitive dysfunctions, suggesting its utility in clinical settings for early detection and personalized treatment strategies. Further research is needed to determine the long-term implications of these findings and the reversibility of cognitive dysfunctions.

Source: Benito-León J, Lapeña J, García-Vasco L, Cuevas C, Viloria-Porto J, Calvo-Córdoba A, Arrieta-Ortubay E, Ruiz-Ruigómez M, Sánchez-Sánchez C, García-Cena C. Exploring Cognitive Dysfunction in Long COVID Patients: Eye Movement Abnormalities and Frontal-Subcortical Circuits Implications via Eye-Tracking and Machine Learning. Am J Med. 2024 Apr 5:S0002-9343(24)00217-1. doi: 10.1016/j.amjmed.2024.04.004. Epub ahead of print. PMID: 38583751. https://pubmed.ncbi.nlm.nih.gov/38583751/

Patients with Fibromyalgia Scored Worse in Memory, Attention, Cognitive Function

Press release:

A cross-sectional study demonstrated significant impairments in attention, memory, and higher cognitive functions among a cohort of patients with fibromyalgia and rheumatoid arthritis (RA), according to a study published in Psychology Research and Behavior Management.1

Investigators believe deficits in the fibromyalgia cohort could be explained by secondary symptoms coupled with more severe pain. A cognitive screening could help curate personalized treatment plans to improve the quality of life among patients with RA and fibromyalgia.

“Research directly comparing cognitive performance between patients with fibromyalgia and RA is still scarce. Some studies suggested deficits of similar magnitude in both patient groups,” wrote a group of investigators led by Carmen María Galvez Sánchez, PhD, associated with the Department of Personality, Evaluation and Psychological Treatment at the University of Murcia, Spain. “In response to this exigency, there is a requisite for the evaluation of cognitive impairments in individuals with chronic pain, aiming to formulate and implement interventions rooted in neuropsychological training. This approach is intended to ameliorate cognitive performance and mitigate its consequential impact on health-related quality of life.”

In certain patients with fibromyalgia, cognitive impairment was linked to clinical pain severity, depression, fatigue, insomnia, and anxiety. Similarly, these were also reported in patients with RA, although pain and emotional symptoms within the fibromyalgia cohort.2 Symptoms of fibromyalgia and RA often include depression, fatigue, insomnia, and cognitive issues.

Investigators analyzed the performance in cognitive domains between patients with RA and fibromyalgia using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Questionnaire scores were combined to determine the symptom severity factor, which was used as a control variable within the group comparisons.

A total of 64 patients with fibromyalgia, 34 patients with RA, and 32 healthy controls were included in the study. All patients were female.

Without controlling for the severity of symptoms, patients with either fibromyalgia or RA performed worse when compared with controls in terms of cognitive domains including verbal memory, visual memory, and strategic planning.

Additionally, over deficits were observed in the fibromyalgia cohort compared with RA. Patients with fibromyalgia reported more severe symptoms, such as pain intensity, total pain, anxiety, depression, insomnia, and fatigue, compared with patients with RA. After controlling for symptom severity a significant proportion of cognitive test, a large proportion of cognitive test parameters were not different between rheumatologic cohorts.

Limitations included the lack of information regarding the influence of psychotropic and pain medication on cognitive performance among rheumatic patients. Although the limitation could have been determined using subgroup analysis, the current sample size was too small to form these subgroups.

Further, no data on treatment and disease activity were collected in the RA subgroup and the analysis of the effects of clinical symptoms on cognitive performance was limited. Additionally, not all psychological factors that may impact cognition were assessed in the analysis. The generalizability of findings may be hindered as only women were included in the analysis and the recruitment of subjects was not randomly performed. Lastly, the RA and fibromyalgia diagnoses were performed by different rheumatologists, which may have introduced selection bias.

“Based on the present results, it is recommended that screening for cognitive deficits be part of routine diagnostics for fibromyalgia and RA, which may help to guide the design of personalized interventions to optimize cognitive performance of patients with fibromyalgia and RA,” investigators concluded.

Source: Lana Pine. HCP Live.

Cognition and Memory after Covid-19 in a Large Community Sample

Abstract:

Background: Cognitive symptoms after coronavirus disease 2019 (Covid-19), the disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are well-recognized. Whether objectively measurable cognitive deficits exist and how long they persist are unclear.

Methods: We invited 800,000 adults in a study in England to complete an online assessment of cognitive function. We estimated a global cognitive score across eight tasks. We hypothesized that participants with persistent symptoms (lasting ≥12 weeks) after infection onset would have objectively measurable global cognitive deficits and that impairments in executive functioning and memory would be observed in such participants, especially in those who reported recent poor memory or difficulty thinking or concentrating (“brain fog”).

Results: Of the 141,583 participants who started the online cognitive assessment, 112,964 completed it. In a multiple regression analysis, participants who had recovered from Covid-19 in whom symptoms had resolved in less than 4 weeks or at least 12 weeks had similar small deficits in global cognition as compared with those in the no-Covid-19 group, who had not been infected with SARS-CoV-2 or had unconfirmed infection (-0.23 SD [95% confidence interval {CI}, -0.33 to -0.13] and -0.24 SD [95% CI, -0.36 to -0.12], respectively); larger deficits as compared with the no-Covid-19 group were seen in participants with unresolved persistent symptoms (-0.42 SD; 95% CI, -0.53 to -0.31). Larger deficits were seen in participants who had SARS-CoV-2 infection during periods in which the original virus or the B.1.1.7 variant was predominant than in those infected with later variants (e.g., -0.17 SD for the B.1.1.7 variant vs. the B.1.1.529 variant; 95% CI, -0.20 to -0.13) and in participants who had been hospitalized than in those who had not been hospitalized (e.g., intensive care unit admission, -0.35 SD; 95% CI, -0.49 to -0.20). Results of the analyses were similar to those of propensity-score-matching analyses. In a comparison of the group that had unresolved persistent symptoms with the no-Covid-19 group, memory, reasoning, and executive function tasks were associated with the largest deficits (-0.33 to -0.20 SD); these tasks correlated weakly with recent symptoms, including poor memory and brain fog. No adverse events were reported.

Conclusions: Participants with resolved persistent symptoms after Covid-19 had objectively measured cognitive function similar to that in participants with shorter-duration symptoms, although short-duration Covid-19 was still associated with small cognitive deficits after recovery. Longer-term persistence of cognitive deficits and any clinical implications remain uncertain. (Funded by the National Institute for Health and Care Research and others.).

Source: Hampshire A, Azor A, Atchison C, Trender W, Hellyer PJ, Giunchiglia V, Husain M, Cooke GS, Cooper E, Lound A, Donnelly CA, Chadeau-Hyam M, Ward H, Elliott P. Cognition and Memory after Covid-19 in a Large Community Sample. N Engl J Med. 2024 Feb 29;390(9):806-818. doi: 10.1056/NEJMoa2311330. PMID: 38416429. https://www.nejm.org/doi/10.1056/NEJMoa2311330 (Full text)

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

Abstract:

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.

Source: Fanshawe JB, Sargent BF, Badenoch JB, Saini A, Watson CJ, Pokrovskaya A, Aniwattanapong D, Conti I, Nye C, Burchill E, Hussain ZU, Said K, Kuhoga E, Tharmaratnam K, Pendered S, Mbwele B, Taquet M, Wood GK, Rogers JP, Hampshire A, Carson A, David AS, Michael BD, Nicholson TR, Paddick SM, Leek CE. Cognitive domains affected post-COVID-19; a systematic review and meta-analysis. Eur J Neurol. 2024 Feb 20:e16181. doi: 10.1111/ene.16181. Epub ahead of print. PMID: 38375608. https://onlinelibrary.wiley.com/doi/10.1111/ene.16181 (Full text)