Background and aims. - The association between white matter abnormalities (WMA) and cognitive decline previously reported in poststroke patients has been mainly documented using visual scales. However, automated segmentation of WMA provides a precise determination of the volume of WMA. Nonetheless, it is rarely used in the stroke population and its potential advantage over visual scales is still unsettled. The objective of this study was to examine whether automated segmentation of WMA provides a better account than the visual Fazekas and Wahlund scales of the decline in executive functions and processing speed in stroke patients. Methods. - The analyses were conducted on the 358 patients of the GRECogVASC cohort with an MRI performed at six months poststroke in the Amiens center. WMA were visually analyzed using the Fazekas (subcortical abnormalities) and Wahlund scales. Segmentation was performed using LST (3.0.3). Following preliminary studies to determine the optimal segmentation threshold, we examined the relationship between cognitive status and WMA volume computed at each threshold using receiver operating characteristic (ROC) curves. Finally, we assessed the ability of both Fazekas and Wahlund visual scores and WMA volume to account for cognitive scores by using a bivariate Pearson correlation analysis, comparing correlation coefficients with the Fisher transformation and repeating correlation analysis after adjustment for the lesion volume. Results. - Increasing the threshold led to an underestimation of WMA (P = 0.0001) (significant for a threshold >= 0.2) and an improvement in correct rejection of signal changes in the stroke cavity (P = 0.02) (significant for a threshold <= 0.5), susceptibility artifacts (P = 0.002) (significant for a threshold <= 0.6), and corticospinal degeneration (P = 0.03) (significant for a threshold <= 0.5). WMA volume decreased with increasing threshold (P = 0.0001). Areas under the curve (AUC) did not differ according to the threshold (processing speed: P = 0.85, executive cognitive functions: P = 0.7). Correlation coefficients between cognitive scores and WMA were higher for WMA volume than the Fazekas (processing speed: Z = -3.442, P = 0.001; executive functions: Z = -2.751, P = 0.006) and Wahlund scores (processing speed: Z = -3.615, P = 0.0001; executive functions: Z = -2.769, P = 0.006). Adjustment for lesion volume did not alter the correlations with WMA volume (processing speed: r = -0.327 [95%CI: -0.416; -0.223], P = 0.0001; executive functions: r = -0.262 [95%CI: -0.363; -0.150], P = 0.0001). Conclusion. - This study shows that WMA volume assessed by automated segmentation provides a better account of cognitive disorders than visual analysis. This should favor its wider use to refine imaging determinants of poststroke cognitive disorders. (c) 2024 Elsevier Masson SAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

La prévalence des troubles neurocognitifs (TNC) post-AVC a été souvent étudiée dans la littérature, variant de 7 % à 67,3 %, en raison notamment du score seuil utilisé. L’objectif de notre étude était de définir la prévalence des TNC post-AVC au sein de l’étude GRECOG-VASC et d’optimiser le score seuil de TNC en utilisant un critère de validité externe optimisé. Cette étude est issue de la cohorte GRECOG-VASC. Nous avons évalué 404 patients à 6 mois post-AVC (présentant un infarctus cérébral dans 91,3 % des cas), ainsi que 1003 sujets contrôles sains, avec la batterie standardisée du NINDS-CSN. Les critères influençant la prévalence ont été examinés en utilisant le taux de faux positifs comme critère de validité externe. Le diagnostic de TNC léger et majeur était basé sur les critères VASCOG. Le critère optimal de TNC était le « score global abrégé » (performance moyenne pour la rapidité d’action, les fonctions exécutives et le langage), puisqu’il était associé au taux corrigé de vrai-positif le plus élevé (p = 0,0001) avec un taux de faux-positif ≤ 5 %. Avec ce critère, la prévalence moyenne des TNC post-AVC était de 49,5 % [44,6–54,4], correspondant pour la plupart à un trouble neurocognitif léger (39,1 % [34,4–43,9]) plutôt qu’à une démence (10,4 % [7,4–13,4]). Notre travail est le premier combinant l’utilisation du contrôle des taux de faux-positifs, l’utilisation d’un critère de validité externe, et une analyse systématique de différents scores globaux et scores seuils afin de déterminer un critère optimisé de TNC post-AVC. Cette étude a permis d’optimiser l’opérationnalisation des critères de TNC post-AVC. Elle a montré que les TNC légèrs représentent 80 % des patients. Enfin, la méthode utilisée offre un moyen d’harmoniser le diagnostic des TNC post-AVC.

Objective To validate the ability of a specifically developed cognitive risk score to identify patients at risk of poststroke neurocognitive disorders (NCDs) who are eligible for a comprehensive cognitive assessment. Methods After assessing 404 patients (infarct 91.3%) in the Groupe de Reflexion pour l'Evaluation Cognitive VASCulaire (GRECogVASC) cross-sectional study with the National Institute of Neurological Disorders and Stroke Canadian Stroke Network battery 6 months after stroke, we used multivariable logistic regression and bootstrap analyses to determine factors associated with NCDs. Independent, internally validated factors were included in a cognitive risk score. Results Cognitive impairment was present in 170 of the 320 patients with a Rankin Scale score The backward logistic regression selected 4 factors (>= 73% of the permutations): NIH Stroke Scale score on admission >= 7 (odds ratio [OR] 2.73, 95% confidence interval [CI] 1.29-4.3, p = 0.005), multiple strokes (OR 3.78, 95% CI 1.6-8, p = 0.002), adjusted Mini-Mental State Examination (MMSEadj) score <= 27 (OR 6.69, 95% CI 3.9-11.6, p = 0.0001), and Fazekas score >= 2 (OR 2.34, 95% CI 1.3-4.2, p = 0.004). The cognitive risk score computed with these 4 factors provided good calibration, discrimination (overoptimism-corrected C = 0.793), and goodness of fit (Hosmer-Lemeshow test p 0.99). A combination of Rankin Scale score >= 1, cognitive risk score >= 1 and MMSEadj score >= 21 selected 230 (56.9%) of the 404 patients for a comprehensive assessment. This procedure yielded good sensitivity (96.5%) and moderate specificity (43%; positive predictive value 0.66, negative predictive value 0.91) and was more accurate (p <= 0.03 for all) than the sole use of screening tests (MMSE or Montreal Cognitive Assessment). Conclusion The GRECogVASC cognitive risk score comprises 4 easily documented factors; this procedure helps to identify patients at risk of poststroke NCDs who must therefore undergo a comprehensive assessment. ClinicalTrials.gov identifier: NCT01339195.

Background and Purpose— The prevalence of poststroke neurocognitive disorder (NCD) has yet to be accurately determined. The primary objective of the present study was to optimize operationalization of the criterion for NCD by using an external validity criterion. Methods— The GRECOG-VASC cohort (Groupe de Réflexion pour l'Évaluation Cognitive Vasculaire) of 404 stroke patients with cerebral infarct (91.3%) or hemorrhage (18.7%) was assessed 6 months poststroke and 1003 healthy controls, with the National Institute of Neurological Disorders and Stroke-Canadian Stroke Network standardized battery. Three dimensions of the criterion for cognitive impairment were systematically examined by using the false-positive rate as an external validity criterion. Diagnosis of mild and major NCD was based on the VASCOG criteria (Vascular Behavioral and Cognitive Disorders). The mechanisms of functional decline were systematically assessed. Results— The optimal criterion for cognitive impairment was the shortened summary score (ie, averaged performance for action speed, executive functions, and language) because it was associated with the highest ( P =0.0001) corrected true-positive rate (43.5%) and a false-positive rate ≤5%. Using this criterion, the mean (95% confidence interval) prevalence of poststroke NCD was 49.5% (44.6–54.4), most of which corresponded to mild NCD (39.1%; 95% confidence interval, 34.4–43.9) rather than dementia (10.4%; 95% confidence interval, 7.4–13.4). Conclusions— This study is the first to have optimized the operationalization of the criterion for poststroke cognitive impairment. It documented the prevalence of poststroke NCD in the GRECOG-VASC cohort and showed that mild cognitive impairment accounts for 80% of the affected patients. Finally, the method developed in the present study offers a means of harmonizing the diagnosis of NCD. Clinical Trial Registration— URL: https://www.clinicaltrials.gov . Unique identifier: NCT01339195.

Vascular cognitive impairment (VCI) includes vascular dementia (VaD), vascular mild cognitive impairment (VaMCI) and mixed dementia. In clinical practice, VCI concerns patients referred for clinical stroke or cognitive complaint. To improve the characterization of VCI and to refine its diagnostic criteria, an international group has elaborated a new standardized evaluation battery of clinical, cognitive, behavioral and neuroradiological data which now constitutes the reference battery. The adaption of the battery for French-speaking subjects is reported as well as preliminary results of the on-going validation study of the GRECOG-VASC group [Clinical Trial NCT01339195]. The diagnostic accuracy of various screening tests is reviewed and showed an overall sub-optimal sensitivity (<0.8). Thus, the general recommendation is to perform systematically a comprehensive assessment in stroke patients at risk of VCI. Furthermore,the use of a structured interview has been shown to increase the detection of dementia. In addition to the well known NINDS-AIREN criteria of VaD, criteria of VCI have been recently proposed which are based on the demonstration of a cognitive disorder by neuropsychological testing and either history of clinical stroke or presence of vascular lesion by neuroimaging suggestive of a link between cognitive impairment and vascular disease. A memory deficit is no longer required for the diagnosis of VaD as it is based on the cognitive decline concerning two or more domains that affect activities of daily living. Both VaMCI and VaD are classified as probable or possible. These new criteria have yet to be validated. Considerable uncertainties remain regarding the determinant of VCI, and especially the lesion amount inducing VCI and VaD. The interaction between lesion amount and its location is currently re-examined using recent techniques for the analysis of MRI data. The high frequency of associated Alzheimer pathology is now assessable in vivo using amyloid imaging. The first studies showed that about a third of patients with VaD due to small vessel disease or with poststroke dementia have amyloid PET imaging suggestive of AD. These new techniques will examine the interaction between vascular lesions and promotion of amyloid deposition. Although results of these on-going studies will be available in few years, these data indicate that efforts should be done in clinical practice to reduce underdiagnosis of VCI; VCI should be examined using a specific protocol which will be fully normalized soon for French-speaking patients; the sub-optimal sensitivity of screening tests prompts to use a structured interview to grade Rankin scale and to perform systematically a comprehensive assessment in stroke patients at risk of VCI; poststroke dementia occurring after 3 months poststroke may be preventable by treatment of modifiable vascular risk factors and secondary prevention of stroke recurrence according to recent recommendations.

Résumé Le paradigme de permutation de tâche s’est imposé ces dernières années dans l’étude des processus mis en jeu dans l’établissement d’une configuration du système cognitif nécessaire à la réalisation d’une tâche. L’objet du présent article est de montrer, à travers une revue de la littérature, comment le contrôle exécutif peut être appréhendé par le biais de ces épreuves où le sujet doit effectuer des changements fréquents de tâche. Une première partie présente le cadre théorique de cette approche. Une seconde partie présente les principaux protocoles et les effets basiques mis en évidence. Sont rapportés enfin des résultats d’études comportementales s’appuyant sur ce paradigme et qui apportent de nouveaux éléments à la connaissance des processus de contrôle exécutifs.

The task switching paradigm has been developed as an experimental paradigm to explore the cognitive control required to configure mental resources that are appropriate to perform a given task. Research reviewed in this article shows that these control processes can be probed by requiring subjects to switch frequently among a small set of simple tasks. First, we describe the theoretical framework of this approach, and we address the question of task-set control. In the second part we review the main experimental approaches to task switching, and we consider theoretical accounts of switch cost and task preparation. In the third and final part, we focus mainly on particular cognitive behavioral studies performed on healthy young human adults and we consider the phenomena and the related mechanisms of cognitive control evidenced in these task switching experiments.

Small artery infarction, which is particularly prevalent among Asians (1), carries a lower risk of recurrent stroke at one-month compared with other stroke subtypes, but long-term findings are inconsistent (2,3). Data on subsequent myocardial infarction risk after small artery stroke are limited. We compared the incidence of vascular events following ischemic stroke due to small artery disease vs. other etiologies among prospectively recruited Asian patients admitted to the Singapore General Hospital from 2005 to 2007. Telephone follow up at a median of 30 months (IQR 24–34) masked to clinical information was obtained for 89% of the cohort. Among the 731 patients with known stroke etiology, 49% had small artery infarction, 38% had large artery infarction, 12% had cardioembolic, and 1% had other etiology. Figure 1 shows the cumulative incidence of subsequent vascular events. Using Cox regression adjusted for age, gender, hypertension, diabetes, hyperlipidemia, smoking, and atrial fibrillation, small artery infarction was associated with a lower incidence of recurrent stroke [hazard ratio (HR) 0·62; P = 0·047], myocardial infarction (HR 0·45; P = 0·031), vascular death (HR 0·18; P = 0·002), and composite vascular events (HR 0·59, P = 0·007) compared with nonsmall artery stroke. The lower risk of subsequent vascular events following small artery infarction may be explained by a differing underlying pathology from large artery and Correspondence: Deidre Anne De Silva*, Department of Neurology, Singapore General Hospital Campus, National Neuroscience Institute, 169608 Singapore. E-mail: gnrdsd@sgh.com.sg

Small artery infarction, which is particularly prevalent among Asians (1), carries a lower risk of recurrent stroke at one-month compared with other stroke subtypes, but long-term findings are inconsistent (2,3). Data on subsequent myocardial infarction risk after small artery stroke are limited. We compared the incidence of vascular events following ischemic stroke due to small artery disease vs. other etiologies among prospectively recruited Asian patients admitted to the Singapore General Hospital from 2005 to 2007. Telephone follow up at a median of 30 months (IQR 24–34) masked to clinical information was obtained for 89% of the cohort. Among the 731 patients with known stroke etiology, 49% had small artery infarction, 38% had large artery infarction, 12% had cardioembolic, and 1% had other etiology. Figure 1 shows the cumulative incidence of subsequent vascular events. Using Cox regression adjusted for age, gender, hypertension, diabetes, hyperlipidemia, smoking, and atrial fibrillation, small artery infarction was associated with a lower incidence of recurrent stroke [hazard ratio (HR) 0·62; P = 0·047], myocardial infarction (HR 0·45; P = 0·031), vascular death (HR 0·18; P = 0·002), and composite vascular events (HR 0·59, P = 0·007) compared with nonsmall artery stroke. The lower risk of subsequent vascular events following small artery infarction may be explained by a differing underlying pathology from large artery and Correspondence: Deidre Anne De Silva*, Department of Neurology, Singapore General Hospital Campus, National Neuroscience Institute, 169608 Singapore. E-mail: gnrdsd@sgh.com.sg

The present study tested the hypothesis that task-switch frequency triggers adjustments of task-set control processes. A mixed-task condition where task switches are frequent should promote flexibility-thus improving task-switch performance-whereas a condition where task repetitions are more expected should favour stability-thus improving task-repeat performance. In two experiments, participants performed single-task and mixed-task blocks. In mixed-task blocks, tasks varied randomly on a trial-by-trial basis. For half of the mixed-task blocks, the frequency with which the task changed was 25%, for the other half, it was 50%. Overall, depending on the task-switch frequency, performance on both task-repeat and task-switch trials was modified. Switch cost was reduced and task-repeat performance was altered by the increase in switch probability. This study demonstrates context-sensitive adjustments of task-set control processes. These results further support the view that mixing cost reflects sustained and endogenous components of cognitive control.

OBJECTIVEIn Stroop-like tasks, the detection of conflict triggers adjustments of cognitive control to reduce conflict in subsequent trials. The present study tested the hypothesis of an impaired modulation of conflict monitoring in Parkinson's disease (PD).METHOD18 PD patients and 18 healthy control (HC) participants performed a Stroop-like task in 2 conditions differing in terms of incongruent/congruent stimuli ratio.RESULTSHC participants demonstrated a sustained modulation of interference effect, the interference effect being decreased when the proportion of incongruent stimuli was high. A trial-by-trial analysis also showed that in the HC group, processing an incongruent stimulus reduced interference in the subsequent trial. Unlike controls, PD patients did not demonstrate any transient or sustained reduction of the interference effect.CONCLUSIONWithin the framework of recent models, these results can be interpreted as an impairment of a proactive mode of cognitive control in patients with PD.