Cognitive impairment in young adults with infratentorial infarcts

Validation of the Spanish version of the cerebellar cognitive-affective syndrome scale

Objective: To validate the Spanish version of the Cerebellar Cognitive-Affective Syndrome scale (CCAS-S), originally published in 2018, in patients with cerebellar ataxia and healthy subjects, as an adapted Spanish version based on normative data has not yet been published or validated. Methods: Spanish CCAS-S was -administered prospectively to 158 patients with cerebellar ataxia and 164 matched healthy subjects from -different regions of Spain. Discriminant validity and reliability were evaluated. A subgroup of 30 patients underwent detailed neuropsychological examinations to confirm the construct validity. The Scale for the Assessment and Rating of Ataxia (SARA) and the Brief Ataxia Rating Scale (BARS) were used to assess motor performance. Results: This Spanish instrument demonstrates reliability and exhibits statistically significant differences in performance between patients and healthy subjects. Our analysis revealed lower values for specificity in detecting possible, probable, or definite CCAS compared to those reported in the US validation study when utilizing the original cutoff values. Upon application of the appropriate -correction factor for education, the specificity values approximated those reported for probable and definite CCAS diagnostics in the original investigation. Conclusions: The adapted Spanish CCAS-S has demonstrated validity and good reliability in this cohort. Discriminant validity was satisfactory for probable and definite CCAS when the correction for education was applied, and modified template and instructions have been developed. Further research is necessary to investigate the significance of the possible CCAS category, as diagnosed using the Spanish version, as well as to assess the performance of the corrected scale in other Spanish-speaking countries.

Supra- and infra-tentorial degeneration patterns in primary lateral sclerosis: a multimodal longitudinal neuroradiology study

BACKGROUND

Primary lateral sclerosis (PLS) is traditionally solely associated with progressive upper motor neuron dysfunction manifesting in limb spasticity, gait impairment, bulbar symptoms and pseudobulbar affect. Recent studies have described frontotemporal dysfunction in some patients resulting in cognitive manifestations. Cerebellar pathology is much less well characterised despite sporadic reports of cerebellar disease.

METHODS

A multi-timepoint, longitudinal neuroimaging study was conducted to characterise the evolution of both intra-cerebellar disease burden and cerebro-cerebellar connectivity. The volumes of deep cerebellar nuclei, cerebellar cortical volumes, cerebro-cerebellar structural and functional connectivity were assessed longitudinally in a cohort of 43 individuals with PLS.

RESULTS

Cerebello-frontal, -temporal, -parietal, -occipital and cerebello-thalamic structural disconnection was detected at baseline based on radial diffusivity (RD) and cerebello-frontal decoupling was also evident based on fractional anisotropy (FA) alterations. Functional connectivity changes were also detected in cerebello-frontal, parietal and occipital projections. Volume reductions were identified in the vermis, anterior lobe, posterior lobe, and crura. Among the deep cerebellar nuclei, the dorsal dentate was atrophic. Longitudinal follow-up did not capture statistically significant progressive changes. Significant primary motor cortex atrophy and inter-hemispheric transcallosal degeneration were also captured.

CONCLUSIONS

PLS is not only associated with upper motor neuron dysfunction, but cerebellar cortical volume loss and deep cerebellar nuclear atrophy can also be readily detected. In addition to intra-cerebellar disease burden, cerebro-cerebellar connectivity alterations also take place. Our data add to the evolving evidence of widespread neurodegeneration in PLS beyond the primary motor regions. Cerebellar dysfunction in PLS is likely to exacerbate bulbar, gait and dexterity impairment and contribute to pseudobulbar affect.

The CODECS study: COgnitive DEficits in Cerebellar Stroke

Part of the extra-pyramidal system, the cerebellum is more and more recognized by its non-motor functions known as the cerebellar cognitive affective syndrome. Several studies have identified disturbances specifically in executive and attentional functions after focal cerebellar lesions. However, most studies were performed in small and heterogeneous patient groups. Furthermore, there is a substantial variation in the methodology of assessment. Here, we present the results of a large and homogeneous cohort of patients with isolated uniform cerebellar lesions. After three months post-stroke all patients underwent structural neuroimaging to confirm an isolated lesion and were given neuropsychological testing. The results show that cerebellar lesions relate to mild but long-term cognitive impairment in a broad spectrum of neurocognitive functions compared to normative values. These findings confirm involvement of the cerebellum in cognitive processing and supports the theory of 'dysmetria of thought' based upon uniform cerebellar processing in multiple cognitive domains. This study highlights the following results: 1-Cognitive impairments after isolated cerebellar stroke is confirmed in several cognitive domains. 2-Semantic and phonemic fluency are most affected in cerebellar stroke patients. 3-Verbal deficits show an age-independent long term effect post-stroke and should be studied further in depth. 4-Cognitive disorders after cerebellar stroke are more prominent in women than men.

Continuous manipulation of mental representations is compromised in cerebellar degeneration

We introduce a novel perspective on how the cerebellum might contribute to cognition, hypothesizing that this structure supports dynamic transformations of mental representations. In support of this hypothesis, we report a series of neuropsychological experiments comparing the performance of individuals with degenerative cerebellar disorders on tasks that either entail continuous, movement-like mental operations or more discrete mental operations. In the domain of visual cognition, the cerebellar disorders group exhibited an impaired rate of mental rotation, an operation hypothesized to require the continuous manipulation of a visual representation. In contrast, the cerebellar disorders group showed a normal processing rate when scanning items in visual working memory, an operation hypothesized to require the maintenance and retrieval of remembered items. In the domain of mathematical cognition, the cerebellar disorders group was impaired at single-digit addition, an operation hypothesized to primarily require iterative manipulations along a mental number-line; this group was not impaired on arithmetic tasks linked to memory retrieval (e.g. single-digit multiplication). These results, obtained in tasks from two disparate domains, point to a potential constraint on the contribution of the cerebellum to cognitive tasks. Paralleling its role in motor control, the cerebellum may be essential for coordinating dynamic, movement-like transformations in a mental workspace.

Cerebellar pathology in motor neuron disease: neuroplasticity and neurodegeneration

Amyotrophic lateral sclerosis is a relentlessly progressive multi-system condition. The clinical picture is dominated by upper and lower motor neuron degeneration, but extra-motor pathology is increasingly recognized, including cerebellar pathology. Post-mortem and neuroimaging studies primarily focus on the characterization of supratentorial disease, despite emerging evidence of cerebellar degeneration in amyotrophic lateral sclerosis. Cardinal clinical features of amyotrophic lateral sclerosis, such as dysarthria, dysphagia, cognitive and behavioral deficits, saccade abnormalities, gait impairment, respiratory weakness and pseudobulbar affect are likely to be exacerbated by co-existing cerebellar pathology. This review summarizes in vivo and post mortem evidence for cerebellar degeneration in amyotrophic lateral sclerosis. Structural imaging studies consistently capture cerebellar grey matter volume reductions, diffusivity studies readily detect both intra-cerebellar and cerebellar peduncle white matter alterations and functional imaging studies commonly report increased functional connectivity with supratentorial regions. Increased functional connectivity is commonly interpreted as evidence of neuroplasticity representing compensatory processes despite the lack of post-mortem validation. There is a scarcity of post-mortem studies focusing on cerebellar alterations, but these detect pTDP-43 in cerebellar nuclei. Cerebellar pathology is an overlooked facet of neurodegeneration in amyotrophic lateral sclerosis despite its contribution to a multitude of clinical symptoms, widespread connectivity to spinal and supratentorial regions and putative role in compensating for the degeneration of primary motor regions.

Subacute cognitive impairment after first-ever transient ischemic attack or ischemic stroke in young adults: The ODYSSEY study

Introduction:

We aimed to investigate the prevalence of cognitive impairment in the subacute phase after transient ischemic attack (TIA) and ischemic stroke (IS), factors associated with a vascular cognitive disorder, and the prevalence of subjective cognitive complaints and their relation with objective cognitive performance.

Patients and methods:

In this multicenter prospective cohort study, we recruited patients with first-ever TIA and IS, aged 18–49 years, between 2013 and 2021 for cognitive assessment up to 6 months after index event. We calculated composite Z-scores for seven cognitive domains. We defined cognitive impairment as a composite Z-score < −1.5. We defined major vascular cognitive disorder as a Z-score < −2.0 in one or more cognitive domains.

Results:

Fifty three TIA and 545 IS patients completed cognitive assessment with mean time to assessment of 89.7 (SD 40.7) days. The median NIHSS at admission was 3 (interquartile range, 1–5). Cognitive impairment was common in five domains (up to 37%), with similar proportion in TIA and IS patients. Patients with major vascular cognitive disorder had a lower education level, higher NIHSS scores and more frequent lesions in the left frontotemporal lobe than without vascular cognitive disorder ( p < 0.05 FDR-corrected). Subjective memory and executive cognitive complaints were present in about two-thirds of the patients, but were weakly associated with objective cognitive performance (β: −0.32 and −0.21, respectively).

Discussion and conclusion:

In the subacute phase after TIA or stroke in young adults, cognitive impairment and subjective cognitive complaints are prevalent, but they are weakly associated with each other.

Cerebellar cognitive affective syndrome after acute cerebellar stroke

Introduction

The cerebellum modulates both motor and cognitive behaviors, and a cerebellar cognitive affective syndrome (CCAS) was described after a cerebellar stroke in 1998. Yet, a CCAS is seldom sought for, due to a lack of practical screening scales. Therefore, we aimed at assessing both the prevalence of CCAS after cerebellar acute vascular lesion and the yield of the CCAS-Scale (CCAS-S) in an acute stroke setting.

Materials and methods

All patients admitted between January 2020 and January 2022 with acute onset of a cerebellar ischemic or haemorrhagic first stroke at the CUB-Hôpital Erasme and who could be evaluated by the CCAS-S within a week of symptom onset were included.

Results

Cerebellar acute vascular lesion occurred in 25/1,580 patients. All patients could complete the CCAS-S. A definite CCAS was evidenced in 21/25 patients. Patients failed 5.2 ± 2.12 items out of 8 and had a mean raw score of 68.2 ± 21.3 (normal values 82–120). Most failed items of the CCAS-S were related to verbal fluency, attention, and working memory.

Conclusion

A definite CCAS is present in almost all patients with acute cerebellar vascular lesions. CCAS is efficiently assessed by CCAS-S at bedside tests in acute stroke settings. The magnitude of CCAS likely reflects a cerebello-cortical diaschisis.

Cognitive screen and employment long-term after infratentorial stroke

OBJECTIVES

Motor problems are well-described neurological deficits that occur commonly after an infratentorial ischemic stroke. However, the brain stem and cerebellum are also part of the neural interconnections responsible for cognition, emotions, and behavioral responses. We lack studies on long-term cognitive outcomes and patient employment after an infratentorial stroke. In the present study, we described and compared long-term poststroke cognitive outcomes and employment between patients that experienced infratentorial and supratentorial ischemic strokes.

MATERIALS AND METHODS

We included consecutive patients that experienced an acute ischemic stroke at ≤58 years of age. Patients were classified according to the stroke location. At seven years poststroke, surviving participants were assessed for neurological deficits (National Institutes of Health Stroke Scale [NIHSS]), functional outcome (modified Rankin Scale [mRS]), cognitive function Barrow Neurological Institute Screen (BNIS), and employment.

RESULTS

Among 141 participants, 25 (18%) had infratentorial and 116 (82%) had supratentorial strokes. At the 7-year poststroke follow-up, there was no significant difference in BNIS total scores; with a median of 43 (IQR 40.5-46) and 41 (IQR 38-46) in the infratentorial and supratentorial groups, respectively. This result indicated that cognitive dysfunction occurred frequently in both groups. Similar employment rates were observed in the infratentorial (48%) and supratentorial (55%) groups. Both groups had a median NIHSS score of 0 and a median mRS score of 2 at the 7-year follow-up.

CONCLUSION

Patients who survived an infratentorial or supratentorial ischemic stroke had similar rates of long-term cognitive dysfunction and difficulties in returning and/or remaining at work.

The shifting role of the cerebellum in executive, emotional and social processing across the lifespan

The cerebellum's anatomical and functional organization and network interactions between the cerebellum and the cerebral cortex and subcortical structures are dynamic across the lifespan. Executive, emotional and social (EES) functions have likewise evolved during human development from contributing to primitive behaviors during infancy and childhood to being able to modulate complex actions in adults. In this review, we address how the importance of the cerebellum in the processing of EES functions might change across development. This evolution is driven by the macroscopic and microscopic modifications of the cerebellum that are occurring during development including its increasing connectivity with distant supra-tentorial cortical and sub-cortical regions. As a result of anatomical and functional changes, neuroimaging and clinical data indicate that the importance of the role of the cerebellum in human EES-related networks shifts from being crucial in newborns and young children to being only supportive later in life. In early life, given the immaturity of cortically mediated EES functions, EES functions and motor control and perception are more closely interrelated. At that time, the cerebellum due to its important role in motor control and sequencing makes EES functions more reliant on these computational properties that compute spatial distance, motor intent, and assist in the execution of sequences of behavior related to their developing EES expression. As the cortical brain matures, EES functions and decisions become less dependent upon these aspects of motor behavior and more dependent upon high-order cognitive and social conceptual processes. At that time, the cerebellum assumes a supportive role in these EES-related behaviors by computing their motor and sequential features. We suspect that this evolving role of the cerebellum has complicated the interpretation of its contribution to EES computational demands.

Cognitive Dysfunction following Cerebellar Stroke: Insights Gained from Neuropsychological and Neuroimaging Research

Although the cerebellum has been consistently noted in the process of cognition, the pathophysiology of this link is still under exploration. Cerebellar stroke, in which the lesions are focal and limited, provides an appropriate clinical model disease for studying the role of the cerebellum in the cognitive process. This review article targeting the cerebellar stroke population (1) describes a cognitive impairment profile, (2) identifies the cerebellar structural alterations linked to cognition, and (3) reveals possible mechanisms of cerebellar cognition using functional neuroimaging. The data indicates the disruption of the cerebro-cerebellar loop in cerebellar stroke and its contribution to cognitive dysfunctions. And the characteristic of cognitive deficits are mild, span a broad spectrum, dominated by executive impairment. The consideration of these findings could contribute to deeper and more sophisticated insights into the cognitive function of the cerebellum and might provide a novel approach to cognitive rehabilitation. The goal of this review is to spread awareness of cognitive impairments in cerebellar disorders.

Post-Stroke Cognitive Impairment: Epidemiology, Risk Factors, and Management

Stroke, characterized as a neurological deficit of cerebrovascular cause, is very common in older adults. Increasing evidence suggests stroke contributes to the risk and severity of cognitive impairment. People with cognitive impairment following stroke often face with quality-of-life issues and require ongoing support, which have a profound effect on caregivers and society. The high morbidity of post-stroke cognitive impairment (PSCI) demands effective management strategies, in which preventive strategies are more appealing, especially those targeting towards modifiable risk factors. In this review article, we attempt to summarize existing evidence and knowledge gaps on PSCI: elaborating on the heterogeneity in current definitions, reporting the inconsistent findings in PSCI prevalence in the literature, exploring established or less established predictors, outlining prevention and treatment strategies potentially effective or currently being tested, and proposing promising directions for future research.

Similar Profile and Magnitude of Cognitive Impairments in Focal and Generalized Epilepsy: A Pilot Study

Introduction: Cognitive impairments in epilepsy are not well-understood. In addition, long-term emotional, interpersonal, and social consequences of the underlying disturbances are important to evaluate.

Purpose: To compare cognitive function including language in young adults with focal or generalized epilepsy. In addition, quality of life and self-esteem were investigated.

Patients and Methods: Young adults with no primary intellectual disability, 17 with focal epilepsy and 11 with generalized epilepsy participated and were compared to 28 healthy controls. Groups were matched on age (mean = 26 years), sex, and education. Participants were administered a battery of neuropsychological tasks and carried out self-ratings of quality of life, self-esteem, and psychological problems.

Results: Similar impairments regarding cognitive function were noted in focal and generalized epilepsy. The cognitive domains tested were episodic long-term memory, executive functions, attention, working memory, visuospatial functions, and language. Both epilepsy groups had lower results compared to controls (effect sizes 0.24–1.07). The total number of convulsive seizures was predictive of episodic long-term memory function. Participants with focal epilepsy reported lower quality of life than participants with generalized epilepsy. Lowered self-esteem values were seen in both epilepsy groups and particularly in those with focal epilepsy. Along with measures of cognitive speed and depression, the total number of seizures explained more than 50% of variation in quality of life.

Conclusion: Interestingly, similarities rather than differences characterized the widespread cognitive deficits that were seen in focal and generalized epilepsy, ranging from mild to moderate. These similarities were modified by quality of life and self-esteem. This study confirms the notion that epilepsy is a network disorder.

Cerebellar degeneration in primary lateral sclerosis: an under-recognized facet of PLS

While primary lateral sclerosis (PLS) has traditionally been regarded as a pure upper motor neuron disorder, recent clinical, neuroimaging and postmortem studies have confirmed significant extra-motor involvement. Sporadic reports have indicated that in addition to the motor cortex and corticospinal tracts, the cerebellum may also be affected in PLS. Cerebellar manifestations are difficult to ascertain in PLS as the clinical picture is dominated by widespread upper motor neuron signs. The likely contribution of cerebellar dysfunction to gait disturbance, falls, pseudobulbar affect and dysarthria may be overlooked in the context of progressive spasticity. The objective of this study is the comprehensive characterization of cerebellar gray and white matter degeneration in PLS using multiparametric quantitative neuroimaging methods to systematically evaluate each cerebellar lobule and peduncle. Forty-two patients with PLS and 117 demographically-matched healthy controls were enrolled in a prospective MRI study. Complementary volumetric and voxelwise analyses revealed focal cerebellar alterations instead of global cerebellar atrophy. Bilateral gray matter volume reductions were observed in lobules III, IV and VIIb. Significant diffusivity alterations within the superior cerebellar peduncle indicate disruption of the main cerebellar outflow tracts. These findings suggest that the considerable intra-cerebellar disease-burden is coupled with concomitant cerebro-cerebellar connectivity disruptions. While cerebellar dysfunction is challenging to demonstrate clinically, cerebellar pathology is likely to be a significant contributor to disability in PLS.

Neurocognitive Deficits and Sequelae Following Severe hand, foot, and mouth disease from 2009 to 2017, in JiangSu Province, China: A Long-Term Follow-Up Study

BACKGROUND

To evaluate the long-term sequela and cognitive profile resulting from severe hand, foot and mouth disease (HFMD) with central nervous system (CNS) involvement.

METHODS

Two-hundred-and-ninety-four HFMD cases were included in a retrospective follow-up study. Physical examination were conducted. The Chinese Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV) was used to assess intelligence.

RESULTS

Fifty-eight mild HFMD cases and 99 severe HFMD cases with mild CNS involvement did not present any neurological sequelae. While the sequelae incidence of severe HFMD with more severe CNS complications were 50.0%. The proportion of full scale intelligence quotient (FSIQ) impairment was 45.0%. In the 2:6-3:11 age group, severe HFMD with more severe CNS complications and lower maternal education level were risk factors for verbal comprehension disorder. Urban-rural residence and lower paternal education level were risk factors for FSIQ disorder. Furthermore, in the 4:0-6:11 age group, severe HFMD with more severe CNS complication was a risk factor for visual spatial disorder and fluid reasoning disorder. Lower paternal education level was a risk factor for FSIQ disorder.

CONCLUSION

Early assessment and intervention among severe HFMD patients with more severe CNS involvement at a very young age will prove beneficial for their future performance.

Genotype-associated cerebellar profiles in ALS: focal cerebellar pathology and cerebro-cerebellar connectivity alterations

OBJECTIVE

Cerebellar disease burden and cerebro-cerebellar connectivity alterations are poorly characterised in amyotrophic lateral sclerosis (ALS) despite the likely contribution of cerebellar pathology to the clinical heterogeneity of the condition.

METHODS

A prospective imaging study has been undertaken with 271 participants to systematically evaluate cerebellar grey and white matter alterations, cerebellar peduncle integrity and cerebro-cerebellar connectivity in ALS. Participants were stratified into four groups: (1) patients testing positive for GGGGCC repeat expansions in C9orf72, (2) patients carrying an intermediate-length repeat expansion in ATXN2, (3) patients without established ALS-associated mutations and (4) healthy controls. Additionally, the cerebellar profile of a single patient with ALS who had an ATXN2 allele length of 62 was evaluated. Cortical thickness, grey matter and white matter volumes were calculated in each cerebellar lobule complemented by morphometric analyses to characterise genotype-associated atrophy patterns. A Bayesian segmentation algorithm was used for superior cerebellar peduncle volumetry. White matter diffusivity parameters were appraised both within the cerebellum and in the cerebellar peduncles. Cerebro-cerebellar connectivity was assessed using deterministic tractography.

RESULTS

Cerebellar pathology was confined to lobules I-V of the anterior lobe in patients with sporadic ALS in contrast to the considerable posterior lobe and vermis disease burden identified in C9orf72 mutation carriers. Patients with intermediate ATXN2 expansions did not exhibit significant cerebellar pathology.

CONCLUSIONS

Focal rather than global cerebellar degeneration characterises ALS. Pathognomonic ALS symptoms which are typically attributed to other anatomical regions, such as dysarthria, dysphagia, pseudobulbar affect, eye movement abnormalities and cognitive deficits, may be modulated, exacerbated or partially driven by cerebellar changes in ALS.

Post-Stroke Cognitive Impairment is Frequent After Infra-Tentorial Infarct

BACKGROUND AND PURPOSE

Post-stroke cognitive impairment is a common and well-known consequence of supra-tentorial infarct, but its prevalence and severity after infra-tentorial infarct is unclear. We compared the frequencies and prognostic value of domain-specific cognitive deficits after supra-tentorial and infra-tentorial infarct.

METHODS

In a consecutive cohort of patients with first-ever stroke (N = 244) admitted to Helsinki University Hospital, 37 patients had an infra-tentorial infarct. Patients were assessed with a comprehensive neuropsychological examination 3 months post-stroke covering 9 cognitive domains and functional disability was assessed at 15 months with the modified Rankin Scale.

RESULTS

There were no statistically significant differences between the frequencies of cognitive deficits in patients with infra-tentorial vs supra-tentorial infarct. Altogether 73% of patients with infra-tentorial infarct and 82% of patients with supra-tentorial infarct had impairment in at least one cognitive domain. Further 42% of patients with infra-tentorial infarct and 47% of those with supra-tentorial infarct had deficits in 3 or more cognitive domains. In patients with infra-tentorial infarct, visuo-constructional deficits were significantly associated with functional disability at 15 months (OR 9.0, 95%CI 1.3-62.5, p = 0.027). In patients with supratentorial infarct, executive deficits (OR 2.9, 95%CI 1.5-5.8, p = 0.002) and visuo-constructional deficits (OR 2.9, 95%CI 1.5-5.7, p = 0.001) showed associations with functional disability at 15 months.

CONCLUSION

Cognitive deficits are as common in patients with infra-tentorial infarct as in those with supra-tentorial infarct, and it is important to recognize them to meet the needs of rehabilitation.

Mapping the Cerebellar Cognitive Affective Syndrome in Patients with Chronic Cerebellar Strokes

The cerebellar cognitive affective syndrome (CCAS) has been consistently described in patients with acute/subacute cerebellar injuries. However, studies with chronic patients have had controversial findings that have not been explored with new cerebellar-target tests, such as the CCAS scale (CCAS-S). The objective of this research is to prove and contrast the usefulness of the CCAS-S and the Montreal Cognitive Assessment (MoCA) test to evaluate cognitive/affective impairments in patients with chronic acquired cerebellar lesions, and to map the cerebellar areas whose lesions correlated with dysfunctions in these tests. CCAS-S and MoCA were administrated to 22 patients with isolated chronic cerebellar strokes and a matched comparison group. The neural bases underpinning both tests were explored with multivariate lesion-symptom mapping (LSM) methods. MoCA and CCAS-S had an adequate test performance with efficient discrimination between patients and healthy volunteers. However, only impairments determined by the CCAS-S resulted in significant regional localization within the cerebellum. Specifically, patients with chronic cerebellar lesions in right-lateralized posterolateral regions manifested cognitive impairments inherent to CCAS. These findings concurred with the anterior-sensorimotor/posterior-cognitive dichotomy in the human cerebellum and revealed clinically intra- and cross-lobular significant regions (portions of right lobule VI, VII, Crus I-II) for verbal tasks that overlap with the "language" functional boundaries in the cerebellum. Our findings prove the usefulness of MoCA and CCAS-S to reveal cognitive impairments in patients with chronic acquired cerebellar lesions. This study extends the understanding of long-term CCAS and introduces multivariate LSM methods to identify clinically intra- and cross-lobular significant regions underpinning chronic CCAS.

Infratentorial pathology in frontotemporal dementia: cerebellar grey and white matter alterations in FTD phenotypes

The contribution of cerebellar pathology to cognitive and behavioural manifestations is increasingly recognised, but the cerebellar profiles of FTD phenotypes are relatively poorly characterised. A prospective, single-centre imaging study has been undertaken with a high-resolution structural and diffusion tensor protocol to systematically evaluate cerebellar grey and white matter alterations in behavioural-variant FTD(bvFTD), non-fluent variant primary progressive aphasia(nfvPPA), semantic-variant primary progressive aphasia(svPPA), C9orf72-positive ALS-FTD(C9 + ALSFTD) and C9orf72-negative ALS-FTD(C9-ALSFTD). Cerebellar cortical thickness and complementary morphometric analyses were carried out to appraise atrophy patterns controlling for demographic variables. White matter integrity was assessed in a study-specific white matter skeleton, evaluating three diffusivity metrics: fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD). Significant cortical thickness reductions were identified in: lobule VII and crus I in bvFTD; lobule VI VII, crus I and II in nfvPPA; and lobule VII, crus I and II in svPPA; lobule IV, VI, VII and Crus I and II in C9 + ALSFTD. Morphometry revealed volume reductions in lobule V in all groups; in addition to lobule VIII in C9 + ALSFTD; lobule VI, VIII and vermis in C9-ALSFTD; lobule V, VII and vermis in bvFTD; and lobule V, VI, VIII and vermis in nfvPPA. Widespread white matter alterations were demonstrated by significant fractional anisotropy, axial diffusivity and radial diffusivity changes in each FTD phenotype that were more focal in those with C9 + ALSFTD and svPPA. Our findings indicate that FTD subtypes are associated with phenotype-specific cerebellar signatures with the selective involvement of specific lobules instead of global cerebellar atrophy.

The relationship between neurofilament light chain and cognition in neurological disorders: A scoping review

Neurofilament light chain (NfL) is an emerging biomarker of neural degeneration. NfL is an integral component of axons and is released into the bloodstream and cerebrospinal fluid during neurodegeneration; hence it can be used to monitor disease progression. Given that several neurological disorders are accompanied by cognitive decline, recent literature has investigated the relationship between NfL levels and cognition. The objective of this scoping review was to determine whether a consistent relationship between NfL and cognition exists in the context of variable degrees of neurodegeneration present across several neurological disorders. Four electronic databases were searched for relevant articles and 160 articles were initially identified. After article screening, 37 studies met the final inclusion criteria. Studies were then qualitatively synthesized to determine the relationship between NfL and cognition across a variety of neurological disorders. The large majority of studies found that NfL levels are inversely correlated with cognition, such that higher NfL levels are associated with poorer cognition. This relationship was not universal, however, and this discrepancy was speculated to be due to the nature of the neurological disorder, individual differences between participants, or methodological inconsistencies. Further study is required, and associated recommendations were proposed for the design of future investigations.

Emotional disorders and the cerebellum: Neurobiological substrates, neuropsychiatry, and therapeutic implications

The notion that the cerebellum is devoted exclusively to motor control has been replaced by a more sophisticated understanding of its role in neurological function, one that includes cognition and emotion. Early clinical reports, as well as physiological and behavioral studies in animal models, raised the possibility of a nonmotor role for the cerebellum. Anatomical studies demonstrate cerebellar connectivity with the distributed neural circuits linked with autonomic, sensorimotor, vestibular, associative, and limbic/paralimbic brain areas. Identification of the cerebellar cognitive affective syndrome in adults and children underscored the clinical relevance of the role of the cerebellum in cognition and emotion. It opened new avenues of investigation into higher-order deficits that accompany the ataxias and other cerebellar diseases, as well as the contribution of cerebellar dysfunction to neuropsychiatric and neurocognitive disorders. Brain imaging studies have demonstrated the complexity of cerebellar functional topography, revealing a double representation of the sensorimotor cerebellum in the anterior lobe and lobule VIII and a triple cognitive representation in the cerebellar posterior lobe, as well as representation in the cerebellum of the intrinsic connectivity networks identified in the cerebral hemispheres. This paradigm shift in thinking about the cerebellum has been advanced by the theories of dysmetria of thought and the universal cerebellar transform, harmonizing the dual anatomic realities of homogeneously repeating cerebellar cortical microcircuitry set against the heterogeneous and topographically arranged cerebellar connections with extracerebellar structures. This new appreciation of cerebellar incorporation into circuits that subserve cognition and emotion mandates a deeper understanding of the cerebellum by practitioners in behavioral neurology and neuropsychiatry because it impacts the understanding and diagnosis of disorders of emotion and intellect and has potential for novel cerebellar-based approaches to therapy.

Post-Stroke Working Memory Dysfunction: A Meta-Analysis and Systematic Review

This review investigates the severity and nature of post-stroke working memory deficits with reference to the multi-component model of working memory. We conducted a systematic search in PubMed up to March 2019 with search terms for stroke and memory. Studies on adult stroke patients, that included a control group, and assessed working memory function, were selected. Effect sizes (Hedges' g) were extracted from 50 studies (in total 3,084 stroke patients) based on the sample size, mean and standard deviation of patients and controls. Performance of stroke patients was compared to healthy controls on low-load (i.e. capacity) and high-load (executively demanding) working memory tasks, grouped by modality (verbal, non-verbal). A separate analysis compared patients in the sub-acute and the chronic stage. Longitudinal studies and effects of lesion location were systematically reviewed. Stroke patients demonstrated significant deficits in working memory with a moderate effect size for both low-load (Hedges' g = -.58 [-.82 to -.43]) and high-load (Hedges' g = -.59 [-.73 to -.45]) tasks. The effect sizes were comparable for verbal and non-verbal material. Systematically reviewing the literature showed that working memory deficits remain prominent in the chronic stage of stroke. Lesions in a widespread fronto-parietal network are associated with working memory deficits. Stroke patients show decrements of moderate magnitude in all subsystems of working memory. This review clearly demonstrates the global nature of the impairment in working memory post-stroke.

Working Memory Impairments in Cerebellar Disorders of Childhood

The cerebellum is a crucial center for motor control and integration. Increasing evidence supports the notion that the cerebellum is also involved in nonmotor functions. Along these lines, multiple cerebellar disorders of childhood and adulthood are associated with behavioral and cognitive symptoms, including impairments in memory. One form of memory commonly affected in cerebellar disorders is working memory, which uses attention to manipulate information that is immediately available to execute cognitive tasks. This article reviews the literature illustrating that working memory impairments are frequently observed in acquired, congenital, and genetic/developmental cerebellar disorders of childhood. Functional neuroimaging studies demonstrate that working memory tasks engage many posterior regions of the cerebellar hemispheres and vermis. Thus, the cerebellum acts as one important node in the working memory circuit, and when the cerebellum is involved in childhood disorders, deficits in working memory commonly occur.

Prism Adaptation Modulates Connectivity of the Intraparietal Sulcus with Multiple Brain Networks

Prism adaptation (PA) alters spatial cognition according to the direction of visual displacement by temporarily modifying sensorimotor mapping. Right-shifting prisms (right PA) improve neglect of left visual field in patients, possibly by decreasing activity in the left hemisphere and increasing it in the right. Left PA shifts attention rightward in healthy individuals by an opposite mechanism. However, functional imaging studies of PA are inconsistent, perhaps because of differing activation tasks. We measured resting-state functional connectivity (RSFC) in healthy individuals before and after PA. When contrasted, right versus left PA decreased RSFC in the spatial navigation network defined by the right posterior parietal cortex (PPC), hippocampus, and cerebellum. Within-PA-direction comparisons showed that right PA increased RSFC in subregions of the PPCs and between the PPCs and the right middle frontal gyrus and left PA decreased RSFC between these regions. Both right and left PA decreased RSFC between the PPCs and bilateral temporal areas. In summary, right PA increases connectivity in the right frontoparietal network and left PA produces essentially opposite effects. Furthermore, right, compared with left, PA modulates RSFC in the right hemisphere navigation network.

The Cerebellar Cognitive Affective/Schmahmann Syndrome: a Task Force Paper

Sporadically advocated over the last two centuries, a cerebellar role in cognition and affect has been rigorously established in the past few decades. In the clinical domain, such progress is epitomized by the "cerebellar cognitive affective syndrome" ("CCAS") or "Schmahmann syndrome." Introduced in the late 1990s, CCAS reflects a constellation of cerebellar-induced sequelae, comprising deficits in executive function, visuospatial cognition, emotion-affect, and language, over and above speech. The CCAS thus offers excellent grounds to investigate the functional topography of the cerebellum, and, ultimately, illustrate the precise mechanisms by which the cerebellum modulates cognition and affect. The primary objective of this task force paper is thus to stimulate further research in this area. After providing an up-to-date overview of the fundamental findings on cerebellar neurocognition, the paper substantiates the concept of CCAS with recent evidence from different scientific angles, promotes awareness of the CCAS as a clinical entity, and examines our current insight into the therapeutic options available. The paper finally identifies topics of divergence and outstanding questions for further research.

Volumetric reduction of cerebellar lobules associated with memory decline across the adult lifespan

Background

The human cerebellum plays an essential role in motor control, is involved in cognitive function and helps to regulate emotional responses. However, little is known about the relationship between cerebellar lobules and age-related memory decline. We aimed to investigate volume alterations in cerebellar lobules at different ages and assess their correlations with reduced memory recall abilities.

Methods

A sample of 275 individuals were divided into the following four groups: 20-35 years (young), 36-50 years (early-middle age), 51-65 years (late-middle age), and 66-89 years (old). Volumes of the cerebellar lobules were obtained using volBrain software. Analysis of covariance and post hoc analysis were used to analyze group differences in cerebellar lobular volumes, and multiple comparisons were performed using the Bonferroni method. Spearman correlation was used to investigate the relationship between lobular volumes and memory recall scores.

Results

In this study, we found that older adults had smaller cerebellar volumes than the other subjects. Volumetric decreases in size were noted in bilateral lobule VI and lobule crus I. Moreover, the volumes of bilateral lobule crus I, lobule VI, and right lobule IV were significantly associated with memory recall scores.

Conclusions

In the present study, we found that some lobules of the cerebellum appear more predisposed to age-related changes than other lobules. These findings provide further evidence that specific regions of the cerebellum could be used to assess the risk of memory decline across the adult lifespan.

The Cerebellar Cognitive Affective/Schmahmann Syndrome: a Task Force Paper

Sporadically advocated over the last two centuries, a cerebellar role in cognition and affect has been rigorously established in the past few decades. In the clinical domain, such progress is epitomized by the "cerebellar cognitive affective syndrome" ("CCAS") or "Schmahmann syndrome." Introduced in the late 1990s, CCAS reflects a constellation of cerebellar-induced sequelae, comprising deficits in executive function, visuospatial cognition, emotion-affect, and language, over and above speech. The CCAS thus offers excellent grounds to investigate the functional topography of the cerebellum, and, ultimately, illustrate the precise mechanisms by which the cerebellum modulates cognition and affect. The primary objective of this task force paper is thus to stimulate further research in this area. After providing an up-to-date overview of the fundamental findings on cerebellar neurocognition, the paper substantiates the concept of CCAS with recent evidence from different scientific angles, promotes awareness of the CCAS as a clinical entity, and examines our current insight into the therapeutic options available. The paper finally identifies topics of divergence and outstanding questions for further research.

Evidence for cognitive resource imbalance in adolescents with narcolepsy

The study investigated brain activity changes during performance of a verbal working memory task in a population of adolescents with narcolepsy. Seventeen narcolepsy patients and twenty healthy controls performed a verbal working memory task during simultaneous fMRI and EEG acquisition. All subjects also underwent MRS to measure GABA and Glutamate concentrations in the medial prefrontal cortex. Activation levels in the default mode network and left middle frontal gyrus were examined to investigate whether narcolepsy is characterized by an imbalance in cognitive resources. Significantly increased deactivation within the default mode network during task performance was observed for the narcolepsy patients for both the encoding and recognition phases of the task. No evidence for task performance deficits or reduced activation within the left middle frontal gyrus was noted for the narcolepsy patients. Correlation analyses between the spectroscopy and fMRI data indicated that deactivation of the anterior aspect of the default mode in narcolepsy patients correlated more with increased concentrations of Glutamate and decreased concentrations of GABA. In contrast, deactivation in the default mode was correlated with increased concentrations of GABA and decreased concentrations of Glutamate in controls. The results suggested that narcolepsy is not characterized by a deficit in working memory but rather an imbalance of cognitive resources in favor of monitoring and maintaining attention over actual task performance. This points towards dysregulation within the sustained attention system being the origin behind self-reported cognitive difficulties in narcolepsy.

Prevalence and short-term changes of cognitive dysfunction in young ischaemic stroke patients

BACKGROUND AND PURPOSE

Information on the prevalence and course of post-stroke cognitive impairment in young stroke patients is limited. The aim was to assess a consecutive sample of acute young ischaemic stroke patients (18-55 years) for the presence and development of neuropsychological deficits.

METHODS

Patients prospectively underwent a comprehensive clinical and cognitive assessment, examining general cognitive function, processing speed, attention, flexibility/executive function and word fluency within the first 3 weeks after hospital admission (median assessment at day 6) and at a 3 months' follow-up (FU). Cognitive dysfunction was defined in comparison to age-standardized published norms.

RESULTS

At baseline (N = 114), deficits were highly prevalent in processing speed (56.0%), flexibility/executive function (49.5%), attention (46.4%) and general cognitive function (42.1%). These frequencies were comparable for those with FU assessment (N = 87). In most domains, cognitive performance improved within 3 months, except for word fluency. However, in about one-third of patients, cognitive deficits (as defined by 1.5 standard deviations below the standardized mean) were still present 3 months after stroke. At FU, 44.0% were impaired in the domain flexibility/executive function, 35.0% in processing speed and 30.0% in attention.

CONCLUSIONS

The high prevalence of cognitive deficits in acute young patients with ischaemic stroke highlights the importance of early post-stroke cognitive assessment to capture a patient's dysfunction in a comprehensive manner and to offer adequate rehabilitation. The role of factors which promote neuropsychological deficits needs further exploration.

Presence of lacunar infarctions is associated with the spatial navigation impairment in patients with mild cognitive impairment: a DTI study

Lacunar cerebral infarction (LI) is one of risk factors of vascular dementia and correlates with progression of cognitive impairment including the executive functions. However, little is known on spatial navigation impairment and its underlying microstructural alteration of white matter in patients with LI and with or without mild cognitive impairment (MCI). Our aim was to investigate whether the spatial navigation impairment correlated with the white matter integrity in LI patients with MCI (LI-MCI). Thirty patients with LI were included in the study and were divided into LI-MCI (n=17) and non MCI (LI-Non MCI) groups (n=13) according neuropsychological tests.The microstructural integrity of white matter was assessed by calculating a fractional anisotropy (FA) and mean diffusivity (MD) from diffusion tensor imaging (DTI) scans. The spatial navigation accuracy, separately evaluated as egocentric and allocentric, was assessed by a computerized human analogue of the Morris Water Maze tests Amunet. LI-MCI performed worse than the CN and LI-NonMCI groups on egocentric and delayed spatial navigation subtests. LI-MCI patients have spatial navigation deficits. The microstructural abnormalities in diffuse brain regions, including hippocampus, uncinate fasciculus and other brain regions may contribute to the spatial navigation impairment in LI-MCI patients at follow-up.

Cognitive aspects: sequencing, behavior, and executive functions

The question posed today is not whether the cerebellum plays a role in cognition, but instead, how the cerebellum contributes to cognitive processes, even in the developmental age. The central role of the cerebellum in many areas of human abilities, motor as well as cognitive, in childhood as well as in adulthood, is well established but cerebellar basic functioning is still not clear and is much debated. Of particular interest is the changing face of cerebellar influence on motor, higher cognitive, and behavioral functioning when adult and developmental lesions are compared. The idea that the cerebellum might play quite different roles during development and in adulthood has been proposed, and evidence from experimental and clinical literature has been provided, including for sequencing, behavioral aspects, and executive functions Still, more data are needed to fully understand the changes of cerebrocerebellar interactions within the segregated loops which connect cerebrum and cerebellum, not only between childhood and adulthood but also in health and disease.

The cerebellar cognitive affective/Schmahmann syndrome scale

Cerebellar cognitive affective syndrome (CCAS; Schmahmann's syndrome) is characterized by deficits in executive function, linguistic processing, spatial cognition, and affect regulation. Diagnosis currently relies on detailed neuropsychological testing. The aim of this study was to develop an office or bedside cognitive screen to help identify CCAS in cerebellar patients. Secondary objectives were to evaluate whether available brief tests of mental function detect cognitive impairment in cerebellar patients, whether cognitive performance is different in patients with isolated cerebellar lesions versus complex cerebrocerebellar pathology, and whether there are cognitive deficits that should raise red flags about extra-cerebellar pathology. Comprehensive standard neuropsychological tests, experimental measures and clinical rating scales were administered to 77 patients with cerebellar disease-36 isolated cerebellar degeneration or injury, and 41 complex cerebrocerebellar pathology-and to healthy matched controls. Tests that differentiated patients from controls were used to develop a screening instrument that includes the cardinal elements of CCAS. We validated this new scale in a new cohort of 39 cerebellar patients and 55 healthy controls. We confirm the defining features of CCAS using neuropsychological measures. Deficits in executive function were most pronounced for working memory, mental flexibility, and abstract reasoning. Language deficits included verb for noun generation and phonemic > semantic fluency. Visual spatial function was degraded in performance and interpretation of visual stimuli. Neuropsychiatric features included impairments in attentional control, emotional control, psychosis spectrum disorders and social skill set. From these results, we derived a 10-item scale providing total raw score, cut-offs for each test, and pass/fail criteria that determined 'possible' (one test failed), 'probable' (two tests failed), and 'definite' CCAS (three tests failed). When applied to the exploratory cohort, and administered to the validation cohort, the CCAS/Schmahmann scale identified sensitivity and selectivity, respectively as possible exploratory cohort: 85%/74%, validation cohort: 95%/78%; probable exploratory cohort: 58%/94%, validation cohort: 82%/93%; and definite exploratory cohort: 48%/100%, validation cohort: 46%/100%. In patients in the exploratory cohort, Mini-Mental State Examination and Montreal Cognitive Assessment scores were within normal range. Complex cerebrocerebellar disease patients were impaired on similarities in comparison to isolated cerebellar disease. Inability to recall words from multiple choice occurred only in patients with extra-cerebellar disease. The CCAS/Schmahmann syndrome scale is useful for expedited clinical assessment of CCAS in patients with cerebellar disorders.awx317media15678692096001.

Anatomical Correlates of Neuropsychological Deficits Among Patients With the Cerebellar Stroke

Objective

To investigate the anatomical correlates of the neuropsychological deficits in patients with the cerebellar stroke.

Methods

We screened patients who were admitted to the National Rehabilitation Center with the cerebellar stroke between October 2012 and November 2016. The patients with the cerebellar stroke who underwent neuropsychological testing for which the Seoul Neuropsychological Screening Battery (SNSB) or the SNSB-II were enrolled. The neuropsychological function capacities were compared in accordance with the stroke type (hemorrhagic vs. ischemic) and the location (right/left anterior, right/left posterior intermediate, right/left posterior lateral lobe, and vermis). Mean z-scores were computed to compare the patient performances with the population averages.

Results

Twenty-six patients (15 with ischemic stroke and 11 with hemorrhagic stroke) with a mean age of 54.8±16.6 years were assessed 8.8±9.2 months after the stroke. Differences in the neuropsychological functioning according to the stroke type were not observed. All of the numerical subtests of the stroke patients showed significantly poorer performances compared with the population averages (mean z-score <0), and some of the subtests revealed abnormal performances in attention-, visuospatial function-, memory-, and frontal/executive function-related tasks (mean z-score <−1). The patients with the presence of a lesion in the right posterior intermediate lobe of the cerebellum showed a poorer performance in the subtests evaluating the executive function including the Korean-version Stroop Test (p=0.04), the Digit Symbol Coding Test (p=0.01), and the Korean-version Trail Making Test (p=0.02) compared with the patients without that lesion.

Conclusion

The present study confirms that the cerebellar stroke affects the neuropsychological functioning which is associated with the anatomical site of stroke.

Profiling Cognitive Deficits in Intra-Axial and Extra-Axial Tumors Using Addenbrooke's Cognitive Examination as a Screening Tool: An Indian Experience

BACKGROUND

Tumors of the brain, whether intra- or extra-axial, results in cognitive deficits. The aim of the present study was to profile cognitive deficits using Addenbrooke's Cognitive Examination-Malayalam (ACE-M) as a screen and to determine the sensitivity and specificity of the same.

METHODS

Seventy-four drug naïve patients diagnosed to have brain tumors were assessed for cognitive functioning using ACE-M before surgery.

RESULTS

Patients with high-grade intra-axial tumors showed a significant association on the cognitive domains of registration (0.04), recall (0.01), and visuospatial functioning (0.02). Gender showed an association between registration (0.02) and verbal fluency (0.02) with females performing better while education was significantly associated with retrograde or remote memory (0.00) with college-educated sample performing better. Significance was assumed at P < 0.05. In extra-axial tumors, laterality had a single association with recall (0.02). Males showed a significant cognitive decline on the cognitive domains of attention (0.02), recall (0.05), naming (0.02), and language functions (0.01). College educated group performed better on registration (0.01), recall (0.09), naming (0.00), and visuospatial functioning (0.00). The area under the receiver operating characteristic curve was estimated as 0.75, which indicates fairly good discriminative ability with a cut off of 71/100; sensitivity at 77.3 and specificity fixed at 67.

CONCLUSIONS

ACE-M is capable of bringing out cognitive deficits along with a number of cognitive domains in patients with intra- and extra-axial tumors in the capacity of a screen, with fairly good levels of sensitivity and specificity.

The diagnostic accuracy of the Montreal Cognitive Assessment in inpatient stroke rehabilitation

The Montreal Cognitive Assessment (MoCA) is a commonly used screening measure for cognitive impairment; however, the diagnostic accuracy and optimal cutoff points in inpatients with mild stroke severity is unknown. We examined the diagnostic accuracy of the MoCA in an acute inpatient stroke rehabilitation unit (N = 95). The criterion neuropsychological assessment was the 30-minute National Institute of Neurological Disorders and Stroke-Canadian Stroke Network battery, modified to include the Symbol-Digit Modalities Test and Trail Making Test A & B. The MoCA had moderately strong diagnostic accuracy in receiver operating curve analyses, with areas under the curve ranging from .80 to .89 depending on the threshold for defining cognitive impairment. Sensitivity ranged from .72 to .87, and was generally greater than specificity, which ranged from .60 to .81. The optimal cutoff on the MoCA for detecting mild or greater cognitive impairment was <25/30. The optimal cutoff using more conservative definitions of cognitive impairment ranged from <23-24/30. Exploratory analyses of MoCA subgroups ("normal," "mildly impaired," and "functionally impaired") differed in the frequency and magnitude of impairment on the criterion neuropsychological assessment. These findings inform the clinical use of the MoCA in individuals with mild stroke in an inpatient rehabilitation setting.

Nonmotor Symptoms in Essential Tremor and Other Tremor Disorders

Tremor, like dystonia, is a term used at the phenomenological, syndromic, and aetiopathological level. Parkinsonian, essential, and dystonic tremor are the three most common tremor diagnoses encountered in clinical practice. Investigation of nonmotor symptoms in essential tremor and dystonic tremor syndromes is significantly hampered by the lack of clear clinical diagnostic criteria for these groups at a syndromic level, and the absence of biomarkers which allow definitive diagnosis at an aetiopathological level. Much work is needed in clarifying the motor features of these disorders in order to allow delineation of the nonmotor features of the most common tremor syndromes. With this limitation in mind, this chapter reviews what is known about nonmotor symptoms in these two tremor types. The final sections deal with nonmotor symptoms observed in patients with lesional tremor, thankfully a much more clearly defined albeit less common group of patients.

The Cerebellum: Adaptive Prediction for Movement and Cognition

Over the past 30 years, cumulative evidence has indicated that cerebellar function extends beyond sensorimotor control. This view has emerged from studies of neuroanatomy, neuroimaging, neuropsychology, and brain stimulation, with the results implicating the cerebellum in domains as diverse as attention, language, executive function, and social cognition. Although the literature provides sophisticated models of how the cerebellum helps refine movements, it remains unclear how the core mechanisms of these models can be applied when considering a broader conceptualization of cerebellar function. In light of recent multidisciplinary findings, we examine how two key concepts that have been suggested as general computational principles of cerebellar function- prediction and error-based learning- might be relevant in the operation of cognitive cerebro-cerebellar loops.

Characterizing cerebellar activity during autobiographical memory retrieval: ALE and functional connectivity investigations

Previous neuroimaging research has shown that the cerebellum is often activated during autobiographical memory (AM) retrieval. However, the reliability of that activation, its localization within the cerebellum, and its relationship to other areas of the AM network remains unknown. The current study used Activation Likelihood Estimation meta-analysis (ALE) as well as resting-state and task-related functional connectivity analyses to better characterize cerebellar activation in relation to AM. The ALE meta-analysis was run on 32 neuroimaging studies of AM retrieval. The results revealed a cluster of reliable AM-related activity within the Crus I lobule of the right posterior cerebellum. Using the peak ALE coordinate within Crus I as a seed region, both task-related and resting state functional connectivity analyses were run on fMRI data from 38 healthy participants. To determine the specificity of connectivity patterns to Crus I, we also included a cerebellar seed region in right Lobule VI previously identified in an ALE meta-analysis as associated with working memory. Resting-state functional connectivity analyses indicated that Crus I was intrinsically connected with other areas of the AM network as well as surrounding and contralateral cerebellar regions. In contrast, the Lobule VI seed was functionally connected with cerebral and cerebellar regions typically associated with working memory. The task-related connectivity analyses revealed a similar pattern, where the Crus I seed exhibited significant connectivity with key nodes of the AM network while the Lobule IV seed did not. During a semantic control task, both Crus I and Lobule VI showed significant correlations with a network of regions that was largely distinct from the AM network. Together these results indicate that right Crus I lobule is reliably engaged during AM retrieval and is functionally connected to the AM network both during rest, and more importantly, during AM retrieval.

Executive Function Deficits in Patients after Cerebellar Neurosurgery

The cerebellum has long been perceived as a structure responsible for the human motor function. According to the contemporary approach, however, it plays a significant role in complex behavior regulatory processes. The aim of this study was to describe executive functions in patients after cerebellar surgery. The study involved 30 patients with cerebellar pathology. The control group comprised 30 neurologically and mentally healthy individuals, matched for sex, age, and number of years of education. Executive functions were measured by the Wisconsin Card Sorting Test (WCST), Stroop Color Word Test (SCWT), Trail Making Test (TMT), and working memory by the Digit Span. Compared to healthy controls, patients made more Errors and Perseverative errors in the WCST, gave more Perseverative responses, and had a lower Number of categories completed. The patients exhibited higher response times in all three parts of the SCWT and TMT A and B. No significant differences between the two groups were reported in their performance of the SCWT and TMT with regard to the measures of absolute or relative interference. The patients had lower score on the backward Digit Span. Patients with cerebellar pathology may exhibit some impairment within problem solving and working memory. Their worse performance on the SCWT and TMT could, in turn, stem from their poor motor-somatosensory control, and not necessarily executive deficits. Our results thus support the hypothesis of the cerebellum's mediating role in the regulation of the activity of the superordinate cognitive control network in the brain. (JINS, 2016, 22, 47-57).

Working Memory: Maintenance, Updating, and the Realization of Intentions

"Working memory" refers to a vast set of mnemonic processes and associated brain networks, relates to basic intellectual abilities, and underlies many real-world functions. Working-memory maintenance involves frontoparietal regions and distributed representational areas, and can be based on persistent activity in reentrant loops, synchronous oscillations, or changes in synaptic strength. Manipulation of content of working memory depends on the dorsofrontal cortex, and updating is realized by a frontostriatal '"gating" function. Goals and intentions are represented as cognitive and motivational contexts in the rostrofrontal cortex. Different working-memory networks are linked via associative reinforcement-learning mechanisms into a self-organizing system. Normal capacity variation, as well as working-memory deficits, can largely be accounted for by the effectiveness and integrity of the basal ganglia and dopaminergic neurotransmission.

Quantitative electroencephalographic and neuropsychological investigation of an alternative measure of frontal lobe executive functions: the Figure Trail Making Test

The most frequently used measures of executive functioning are either sensitive to left frontal lobe functioning or bilateral frontal functioning. Relatively little is known about right frontal lobe contributions to executive functioning given the paucity of measures sensitive to right frontal functioning. The present investigation reports the development and initial validation of a new measure designed to be sensitive to right frontal lobe functioning, the Figure Trail Making Test (FTMT). The FTMT, the classic Trial Making Test, and the Ruff Figural Fluency Test (RFFT) were administered to 42 right-handed men. The results indicated a significant relationship between the FTMT and both the TMT and the RFFT. Performance on the FTMT was also related to high beta EEG over the right frontal lobe. Thus, the FTMT appears to be an equivalent measure of executive functioning that may be sensitive to right frontal lobe functioning. Applications for use in frontotemporal dementia, Alzheimer’s disease, and other patient populations are discussed.

Factors related to long-term post-stroke cognitive impairment in young adult ischemic stroke

BACKGROUND

Post-stroke cognitive impairment is common and a decisive prognostic factor. However, few studies have reported on post-stroke cognition in young adults, especially long-term cognition. This study was designed to investigate the influence of baseline factors, treatments, and functional outcome on the long-term cognitive outcome in young adults with ischemic stroke.

MATERIAL AND METHODS

Consecutive patients aged 18-45 years between January 1, 2006 and December 31, 2010, with a first-ever ischemic stroke, were recruited for cognitive assessment by telephone from December 10 to December 31, 2013 using modified versions of "Telephone Instrument for Cognitive Status" (TICS-m) scale. The relationship of cognitive impairment with baseline factors, treatments, and functional outcome were evaluated.

RESULTS

A total of 350 patients with an average age of 41.0±6.8 years (69.7% males and 30.3% females) were reviewed. The average follow-up period was 5.8±3.2 years, and cognitive impairment existed in 39.4% of patients at follow-up. Stroke severity on admission, functional outcome (modified Rankin Scale, mRS >2) at discharge, left anterior circulation syndrome, and stroke recurrence were markedly associated with post-stroke cognitive impairment (all P<0.01). Post-stroke cognition was also significantly related to mRS at follow-up (r=-0.563, P<0.001).

CONCLUSIONS

Post-stroke cognition was related to functional outcome: hence, treatment directed toward reducing functional disability might also reduce cognitive impairment.

Interaction Between Hippocampus and Cerebellum Crus I in Sequence-Based but not Place-Based Navigation

To examine the cerebellar contribution to human spatial navigation we used functional magnetic resonance imaging and virtual reality. Our findings show that the sensory-motor requirements of navigation induce activity in cerebellar lobules and cortical areas known to be involved in the motor loop and vestibular processing. By contrast, cognitive aspects of navigation mainly induce activity in a different cerebellar lobule (VIIA Crus I). Our results demonstrate a functional link between cerebellum and hippocampus in humans and identify specific functional circuits linking lobule VIIA Crus I of the cerebellum to medial parietal, medial prefrontal, and hippocampal cortices in nonmotor aspects of navigation. They further suggest that Crus I belongs to 2 nonmotor loops, involved in different strategies: place-based navigation is supported by coherent activity between left cerebellar lobule VIIA Crus I and medial parietal cortex along with right hippocampus activity, while sequence-based navigation is supported by coherent activity between right lobule VIIA Crus I, medial prefrontal cortex, and left hippocampus. These results highlight the prominent role of the human cerebellum in both motor and cognitive aspects of navigation, and specify the cortico-cerebellar circuits by which it acts depending on the requirements of the task.

Neurological assessment and its relationship to CSF biomarkers in amateur boxers

BACKGROUND

Mild traumatic brain injury (TBI) or concussion is common in many sports. Today, neuropsychological evaluation is recommended in the monitoring of a concussion and in return-to-play considerations. To investigate the sensitivity of neuropsychological assessment, we tested amateur boxers post bout and compared with controls. Further the relationship between neuropsychological test results and brain injury biomarkers in the cerebrospinal fluid (CSF) were investigated.

METHOD

Thirty amateur boxers on high elite level with a minimum of 45 bouts and 25 non-boxing matched controls were included. Memory tests (Rey Osterrieth Complex Figure, Listening Span, Digit Span, Controlled Word Association Test, and computerized testing of episodic memory), tests of processing speed and executive functions (Trail Making, Reaction Time, and Finger Tapping) were performed and related to previously published CSF biomarker results for the axonal injury marker neurofilament light (NFL).

RESULTS

The neurological assessment showed no significant differences between boxers and controls, although elevated CSF NFL, as a sign of axonal injury, was detected in about 80% of the boxers 1-6 days post bout. The investigation of the relationship between neuropsychological evaluation and CSF NFL concentrations revealed that boxers with persisting NFL concentration elevation after at least 14 days resting time post bout, had a significantly poorer performance on Trail Making A (p = 0.041) and Simple Reaction Time (p = 0.042) compared to other boxers.

CONCLUSION

This is the first study showing traumatic axonal brain injury can be present without measureable cognitive impairment. The repetitive, subconcussive head trauma in amateur boxing causes axonal injury that can be detected with analysis of CSF NFL, but is not sufficient to produce impairment in memory tests, tests of processing speed, or executive functions. The association of prolonged CSF NFL increase in boxers with impairment of processing speed is an interesting observation, which needs to be verified in larger studies.

Ischaemic stroke in young adults: risk factors and long-term consequences

Contrary to trends in most other diseases, the average age of ischaemic stroke onset is decreasing, owing to a rise in the incidence of stroke among 'young' individuals (under 50 years of age). This Review provides a critical overview of the risk factors and aetiology of young ischaemic stroke and addresses its long-term prognosis, including cardiovascular risk, functional outcome and psychosocial consequences. We highlight the diminishing role of 'rare' risk factors in the pathophysiology of young stroke in light of the rising prevalence of 'traditional' vascular risk factors in younger age groups. Long-term prognosis is of particular interest to young patients, because of their long life expectancy and major responsibilities during a demanding phase of life. The prognosis of young stroke is not as favourable as previously thought, with respect either to mortality or cardiovascular disease or to psychosocial consequences. Therefore, secondary stroke prevention is probably a life-long endeavour in most young stroke survivors. Due to under-representation of young patients in past trials, new randomized trials focusing on this age group are needed to confirm the benefits of long-term secondary preventive medication. The high prevalence of poor functional outcome and psychosocial problems warrants further study to optimize treatment and rehabilitation for these young patients.