The network structure of cognitive impairment: from Subjective Cognitive Decline to Alzheimer's Disease.

It was proposed that a reorganization of the relationships between cognitive functions occurs in dementia, a vision that surpasses the idea of a mere decline of specific domains. The complexity of cognitive structure, as assessed by neuropsychological tests, can be captured by Exploratory Graph Analysis (EGA).EGA was applied to the neuropsychological assessment of people (humans) with Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI), and Alzheimer's Disease (AD) (Total N=638). Both sexes were included.In AD, memory scores detach from the other cognitive functions and memory subdomains reduce their reciprocal relation. SCD showed a pattern of segregated neuropsychological domains, and MCI showed a noisy and less stable pattern.Results suggest that AD drives a reorganization of cognitive functions toward a less fractionated architecture compared to preclinical conditions. Cognitive functions show a reorganization that goes beyond the performance decline. Results also have clinical implications in test interpretations and usage.Significance Statement The manuscript proposes an innovative vision for the study of the complex reorganization of cognition in people with dementia.We applied a sophisticated, reliable, cutting-edge statistical method (i.e., Exploratory Graph Analysis - EGA) to the neuropsychological evaluations of 638 patients classified into Subjective Cognitive Decline (N=155), Mild Cognitive Impairment (N=242) and Alzheimer's Disease (N=241).Patients with Alzheimer's Disease showed a simplified architecture as compared to subjects with Subjective Cognitive Decline. The MCI group resulted in sharing specific aspects with the SCD and others with the AD.Recognizing the complexity of the cognitive organization is fundamental for properly understanding cognitive impairment and stimulate the discussion about the interpretation of neuropsychological profiles from a more systemic point of view.

Motor Neuron Disease Population-Based Registry in Egypt: Where Do We Stand?

BACKGROUND: There is a growing body of evidence indicating that the worldwide distribution of ALS is far from uniform. This is evident through variations in the epidemiology, genetics, and phenotypical characteristics of amyotrophic lateral sclerosis (ALS) and other motor neuron diseases (MND) across different regions. However, comprehensive ALS epidemiological studies are still lacking in many parts of the world, especially in Africa. Therefore, we propose the establishment of a population-based register for ALS/MND in Egypt, an important part of Africa with a population of more than 100 millions of people. SUMMARY: Given Egypt's distinctive social and demographic characteristics, it is highly recommended to employ specific, recently developed epidemiological techniques for assessing the prevalence and incidence of these diseases within the country. By utilizing these methods, we can gather invaluable data that will contribute to a deeper understanding of ALS and enable us to effectively address its impact on the population of Egypt. KEY MESSAGES: Our goal with this pioneering ALS/MND population-based register in Egypt is to define the burden of ALS in this part of Africa and to increase the chances for this consanguineous population to get access to modern individualized genetic therapies. Additionally, we aspire to uncover potential environmental factors and gene-environment interactions that contribute to the development of ALS. This knowledge of MND individual and group risk in Egypt will not only open doors for interventions but also provide opportunities for future research and discovery.

Mapping lower-limbs muscle vulnerability in patients with ALS: The role of upper and lower motor neurons.

BACKGROUND: Several studies have reported disproportionate wasting of the flexor muscles of the lower limbs (LL) compared to the extensors in patients with amyotrophic lateral sclerosis (ALS). However, these studies have involved small sample sizes (n ã€ˆ100), and their findings have been inconsistent. Thus, it remains uncertain whether a distinct pattern of LL muscle weakness is specific to ALS. AIMS: To investigate the muscle weakness pattern in the LL at the knee, ankle, and toes in a large cohort of ALS patients and evaluate the relationship between the pattern of muscle strength and the extent of upper (UMN) and lower (LMN) motoneuron impairment. MATERIAL AND METHODS: The strength of flexor and extensor muscle was evaluated in 1250 legs of newly diagnosed ALS patients at the knee, ankle, and foot toes. UMN and LMN burden were assessed using validated scores. Within-subjects ANOVA considering the type of muscle (flexor/extensor) and anatomical sites (knee/ankle/toes) and mixed-factorial ANOVA were conducted to explore the impact of UMN and LMN impairments on the muscle weakness pattern. RESULTS: Muscle strength showed a significant decline from proximal to distal regions. Indeed both flexor and extensor muscles at the knee outperformed those at the ankle and toes. Within each site, extensor muscles exhibited less strength than flexor, except at the knee. Patients with heightened UMN impairment showed a more marked difference between flexors and extensors within each site, with extensor muscles being more compromised at the ankle and toes. Higher LMN impairment corresponded to a more pronounced weakness in flexor muscles at the ankle and toes compared to those at the knee. CONCLUSIONS: The extensor muscle at the knee and the flexors at the foot and toes displayed relative resistance to ALS disease. UMN impairment amplified the differences between flexor and extensor muscles within each site, while LMN impairment demonstrated a clear distal-to-proximal vulnerability.

Irisin Levels in Cerebrospinal Fluid Correlate with Biomarkers and Clinical Dementia Scores in Alzheimer Disease.

OBJECTIVE: Irisin, released by muscles during exercise, was recently identified as a neuroprotective factor in mouse models of Alzheimer disease (AD). In a cohort of AD patients, we studied cerebrospinal fluid (CSF) and plasma irisin levels, sex interactions, and correlations with disease biomarkers. METHODS: Correlations between CSF and plasma irisin levels and AD biomarkers (amyloid ß 1-42, hyperphosphorylated tau, and total tau [t-tau]) and Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) were analyzed in a cohort of patients with Alzheimer dementia (n = 82), mild cognitive impairment (n = 44), and subjective memory complaint (n = 20) biologically characterized according to the recent amyloid/tau/neurodegeneration classification. RESULTS: CSF irisin was reduced in Alzheimer dementia patients (p < 0.0001), with lower levels in female patients. Moreover, CSF irisin correlated positively with Aß42 in both female (r = 0.379, p < 0.001) and male (r = 0.262, p < 0.05) patients, and negatively with CDR-SOB (r = -0.234, p < 0.05) only in female patients. A negative trend was also observed between CSF irisin and t-tau levels in all patients (r = -0.144, p = 0.082) and in the female subgroup (r = -0.189, p = 0.084). INTERPRETATION: The results highlight the relationship between irisin and biomarkers of AD pathology, especially in females. Our findings also offer perspectives toward the use of irisin as a marker of the AD continuum. ANN NEUROL 2024;96:61-73.

Nerve conduction study on the split-hand plus index in Amyotrophic lateral sclerosis: correlations with lower motor neuron impairment.

INTRODUCTION: In the arms of patients with Amyotrophic lateral sclerosis (ALS) two peculiar patterns of dissociated muscular atrophy have been described: the split-hand sign (with predominant atrophy of the lateral aspect of the hand, compared to hypothenar eminence) and the split-hand-plus sign (SHPS), a predominant abductor pollicis brevis (ABP) atrophy with sparing of flexor pollicis longus (FPL). AIMS: In this case-control study, we evaluated the diagnostic utility of a neurophysiological indicator of SHPS and assessed its association with clinical features. METHODS: We prospectively studied 59 incident ALS patients, 61 patients with ALS-mimic disorders (OND) and 61 non-neurological controls (NNCs). ABP and FPL compound muscle action potentials (CMAP) amplitudes were obtained by supramaximal stimulation of median nerve at elbow. Split-hand plus index (SHPI) was calculated according to the formula: APB-CMAP/FPL-CMAP. RESULTS: SHPI was significantly lower in ALS compared to OND patients and NNCs (p < 0.0001). SHPI value < 1 was observed in 2% of NNCs and 9% of OND patients and demonstrated an accuracy of 71% in differentiating ALS from OND and an accuracy of 74% in differentiating ALS from NNC. SHPI was associated with higher LMN score, and higher disease severity as quantified by the ALSFRS-r. CONCLUSION: Our results indicate that SHPI is a reliable indicator to distinguish ALS patients from ONDs and NNCs. SHPI was significantly associated to the degree of lower motor neuron impairment but showed no association with upper motoneuron impairment.

Explainable machine learning radiomics model for Primary Progressive Aphasia classification.

Introduction: Primary Progressive Aphasia (PPA) is a neurodegenerative disease characterized by linguistic impairment. The two main clinical subtypes are semantic (svPPA) and non-fluent/agrammatic (nfvPPA) variants. Diagnosing and classifying PPA patients represents a complex challenge that requires the integration of multimodal information, including clinical, biological, and radiological features. Structural neuroimaging can play a crucial role in aiding the differential diagnosis of PPA and constructing diagnostic support systems. Methods: In this study, we conducted a white matter texture analysis on T1-weighted images, including 56 patients with PPA (31 svPPA and 25 nfvPPA), and 53 age- and sex-matched controls. We trained a tree-based algorithm over combined clinical/radiomics measures and used Shapley Additive Explanations (SHAP) model to extract the greater impactful measures in distinguishing svPPA and nfvPPA patients from controls and each other. Results: Radiomics-integrated classification models demonstrated an accuracy of 95% in distinguishing svPPA patients from controls and of 93.7% in distinguishing svPPA from nfvPPA. An accuracy of 93.7% was observed in differentiating nfvPPA patients from controls. Moreover, Shapley values showed the strong involvement of the white matter near left entorhinal cortex in patients classification models. Discussion: Our study provides new evidence for the usefulness of radiomics features in classifying patients with svPPA and nfvPPA, demonstrating the effectiveness of an explainable machine learning approach in extracting the most impactful features for assessing PPA.

Real-life management of patients with mild cognitive impairment: an Italian survey.

BACKGROUND: Mild cognitive impairment (MCI) is a syndrome with heterogeneous underlying causes and different rates of disease progression, whose clinical heterogeneity leads to a wide variation in diagnostic and therapeutic approaches in clinical practice. The lack of uniform practical recommendations on diagnostic workup and treatment for MCI patients hinders optimal management of these patients, worsening their prognosis. Standardized guidelines for the investigation and follow-up of MCI are therefore urgently required. AIM: Aim of our study was to assess the diagnostic and therapeutic approach to MCI patients in the setting of Italian Memory Clinics. METHODS: A survey was delivered to a sample of Italian neurologists through two different phases: a first exploratory phase recording general information about the usual clinical management of patients with MCI, and a subsequent operative phase assessing the practical diagnostic and therapeutic decisions taken in a real life setting to manage subjects with MCI. RESULTS: A total of 121 neurologists participated to the first phase of the survey and 203 patients were enrolled in the second phase. Information gathered in the first phase of the survey highlighted a non-uniform use of diagnostic criteria and procedures for MCI, as well as a very heterogeneous therapeutic strategy among Italian neurologists. In the second phase, recorded data on diagnostic and therapeutic approach confirmed the large variability observed in the first phase of the survey. CONCLUSIONS: The results of our study reflect a suboptimal management of MCI patients in Italy and highlight the need of standardized diagnostic and therapeutic approaches for this condition.

Deep Learning-based Approach for Brainstem and Ventricular MR Planimetry: Application in Patients with Progressive Supranuclear Palsy.

Purpose To develop a fast and fully automated deep learning (DL)-based method for the MRI planimetric segmentation and measurement of the brainstem and ventricular structures most affected in patients with progressive supranuclear palsy (PSP). Materials and Methods In this retrospective study, T1-weighted MR images in healthy controls (n = 84) were used to train DL models for segmenting the midbrain, pons, middle cerebellar peduncle (MCP), superior cerebellar peduncle (SCP), third ventricle, and frontal horns (FHs). Internal, external, and clinical test datasets (n = 305) were used to assess segmentation model reliability. DL masks from test datasets were used to automatically extract midbrain and pons areas and the width of MCP, SCP, third ventricle, and FHs. Automated measurements were compared with those manually performed by an expert radiologist. Finally, these measures were combined to calculate the midbrain to pons area ratio, MR parkinsonism index (MRPI), and MRPI 2.0, which were used to differentiate patients with PSP (n = 71) from those with Parkinson disease (PD) (n = 129). Results Dice coefficients above 0.85 were found for all brain regions when comparing manual and DL-based segmentations. A strong correlation was observed between automated and manual measurements (Spearman ρ > 0.80, P < .001). DL-based measurements showed excellent performance in differentiating patients with PSP from those with PD, with an area under the receiver operating characteristic curve above 0.92. Conclusion The automated approach successfully segmented and measured the brainstem and ventricular structures. DL-based models may represent a useful approach to support the diagnosis of PSP and potentially other conditions associated with brainstem and ventricular alterations. Keywords: MR Imaging, Brain/Brain Stem, Segmentation, Quantification, Diagnosis, Convolutional Neural Network Supplemental material is available for this article. © RSNA, 2024 See also the commentary by Mohajer in this issue.

Neurophysiological indices for split phenomena: correlation with age and sex and potential implications in amyotrophic lateral sclerosis.

Background: Split phenomena (SP) are characterized by patterns of differential muscle wasting and atrophy, which are highly prevalent in amyotrophic lateral sclerosis (ALS) patients. Several neurophysiological indicators, including the split-hand index (SHI), split-leg index (SLI), and split-elbow index (SEI), have been proposed to assess SP. Nevertheless, their cutoff values and the impact of age and sex on these measures remain unclear. Methods: We prospectively collected neurophysiological data from 300 healthy adult subjects. The following indices were measured from compound muscle action potentials (CMAPs): SHI [abductor pollicis brevis (APBcmap) x first dorsal interosseous (FDI)cmap/adductor digiti minimi (ADMcmap)], SEI (BICEPScmap/TRICEPScmap), SLI (extensor digit brevis (EDB)cmap/abductor Hallucis (AH)cmap), and the neurophysiological ratios APBcmap /ADMcmap and FDIcmap/ADMcmap. Multiple linear regression analysis was used to investigate the association between age, sex, CMAPs, and neurophysiological indicators. Results: The median SHI was 10.4, with a median APBcmap/ADMcmap ratio of 0.9 and a median FDIcmap/ADMcmap ratio of 1.2. The median SEI was 1.6 (IQR:1.1-2.4) and the median SLI was 0.7 (IQR:0.5-1.0). Negative associations were observed between age, most of the CMAPs, and all the neurophysiological indices, except for SLI. The male subjects exhibited significantly higher CMAP values for the first dorsal interosseous (FDI), biceps, and SHI compared to the female participants. Conclusion: Our findings highlight the importance of age- and sex-adjusted normative data for SP indices, which could enhance their diagnostic accuracy and clinical utility in patients with ALS. The SL index appears to be the most reliable indicator, as it showed no significant association with age or sex.

Incidence of amyotrophic lateral sclerosis in Chile.

OBJECTIVE: This study aimed to estimate amyotrophic lateral sclerosis (ALS) incidence and survival rates in the Metropolitan region of Chile. METHODS: We conducted a cohort study of ALS cases in the Metropolitan Region from 2016 to 2019. A total of 219 ALS patients were recruited from Corporación ELA-Chile registry, in collaboration with neurologists from Sociedad de Neurología, Psiquiatría y Neurocirugía de Chile. We calculated incidence rates by sex and age and determined median survival from onset and diagnosis. Survival analysis used the Kaplan-Meier statistic, estimating hazard ratios for age, sex, time from symptom onset and from diagnosis using a Weibull regression model. All analyses were done using R 4.1.0. RESULTS: Overall, ALS diagnosis incidence was 0.97 cases per 100,000 inhabitants, peaking in the 70-79 age group and declining thereafter. The male-to-female ratio was 1.23. The median time to death from diagnosis was 2.3 years (95% confidence interval [CI]: 1.9-2.5), and from the first symptom, it was 3.1 years (95% CI: 2.8-3.5). CONCLUSIONS: This is the first population-based study reporting ALS incidence and survival rates in Chile's Metropolitan region. Incidence resembled other Latin American studies. Median survival from diagnosis and from the first symptom were in line with previous findings. Our results corroborated lower ALS rates in Latin America, consistent with prior research.

Incidence of young-onset dementia in Italy: The Brescia register study.

INTRODUCTION: The goal of the present work was to assess the incidence of dementia with onset before the age of 65 years (i.e., young-onset dementia [YOD]) and define the frequencies of young-onset Alzheimer's disease (AD), frontotemporal lobar degeneration (FTLD), and dementia with Lewy bodies (DLB) in the general population. METHODS: The study was conducted from January 1, 2019 to December 31, 2019 in Brescia province (population: 1,268,455). During the study period, all new YOD cases (incident YOD) were counted, and all patients' records reviewed. The incidence was standardized to the Italian general population in 2019. RESULTS: A total of 29 YOD patients were diagnosed. The age-sex standardized incidence rate was 4.58 (95% confidence interval, 3.07-6.58) per 100,000 person-years. No difference in incidence rate between YOD due to AD or FTLD (P = 0.83) and between sexes (P = 0.81) was observed. YOD incidence increased with age, reaching its peak after 60 years. DISCUSSION: Presenting neurodegenerative YOD phenotypes encompasses both AD and FTLD. Improved knowledge on YOD epidemiology is essential to adequately plan and organize health services.

Sarcopenia in subjects with Alzheimer's disease: prevalence and comparison of agreement between EGWSOP1, EGWSOP2, and FNIH criteria.

BACKGROUND: Sarcopenia is an age-related clinical syndrome characterized by the progressive loss of muscle mass and muscle strength. It appears to be closely linked to dementia, particularly Alzheimer's disease (AD); however, its prevalence among AD patients remains unclear. In this study, we assessed differences in sarcopenia prevalence between non-demented individuals and AD patients. Moreover, we assessed sex-specific differences in sarcopenia prevalence and explored the diagnostic value of the Muscle Quality Index (MQI) for diagnosing sarcopenia among AD patients. METHOD: Cross-sectional study including 145 patients with probable AD and 51 older adults with normal cognition. Sarcopenia was diagnosed according to the criteria of the European Working Group on Sarcopenia in Older People (EWGSOP1 and EWGSOP2) and of the Foundation for the National Institutes of Health (FNIH). The MQI was computed as the ratio of handgrip strength to skeletal muscle mass. RESULTS: No significant difference in sarcopenia prevalence was observed between AD patients and controls. Prevalence ranged from 3.4 to 23.4% in AD patients and from 2 to 11.8% in controls, depending on diagnostic criteria. Prevalence was higher using EWGSOP1 and decreased using EWGSOP2 and FNIH. Prevalence was higher in males than in females with AD. The MQI was lower in AD patients than in controls (95%CI: - 0.23, - 0.05, p < 0.001), but displayed poor diagnostic accuracy in identifying sarcopenia cases. CONCLUSIONS: AD patients and controls show comparable sarcopenia prevalence. Sarcopenia prevalence is higher in males than females among AD patients and higher when using EWGSOP1 compared to FNIH and EWGSOP2 criteria.

Risk and sex-specific trends of dementia and stroke in Italy Compared to European and high-income countries and the world: global implications.

BACKGROUND: Understanding the increasing trends in Italy may inform new prevention strategies and better treatments. We investigated trends and risk factors of dementia, stroke, and ischemic heart disease (IHD) in Italy with the second-oldest population globally, compared to European and high-income countries and the world. METHODS: We analyzed the Global Burden of Disease Study (GBD) 2019 estimates on incidence and burden (i.e., disability and death combined) of the three conditions in both sexes. We also analyzed the burden attributable to 12 modifiable risk factors and their changes during 1990-2019. RESULTS: In 2019, Italy had 186,108 new dementias (123,885 women) and 94,074 new strokes (53,572 women). Women had 98% higher crude dementia and 24% higher crude stroke burdens than men. The average age-standardized new dementia rate was 114.7 per 100,000 women and 88.4 per 100,000 men, both higher than Western Europe, the European Union, high-income countries, and the world. During 1990-2019, this rate increased in both sexes (4%), despite a decline in stroke (- 45%) and IHD (- 17%) in Italy. Dementia burden attributable to tobacco decreased in both sexes (- 12.7%) during 1990-2019, while high blood glucose and high body mass index combined burden increased (25.4%). Stroke and IHD had similar trends. CONCLUSIONS: While decreases in new strokes and IHDs are encouraging, new approaches to their joint prevention are required to reverse the rising dementia trends, especially among women. Life course approaches to promoting holistic brain health should be implemented at the community, national, and international levels before the growing trends become overwhelming.

Narcissistic Personality Disorder as Prodromal Feature of Early-Onset, GRN-Positive bvFTD: A Case Report.

Background: Behavioral variant frontotemporal dementia (bvFTD) typically involves subtle changes in personality that can delay a timely diagnosis. Objective: Here, we report the case of a patient diagnosed of GRN-positive bvFTD at the age of 52 presenting with a 7-year history of narcissistic personality disorder, accordingly to DSM-5 criteria. Methods: The patient was referred to neurological and neuropsychological examination. She underwent 3 Tesla magnetic resonance imaging (MRI) and genetic studies. Results: The neuropsychological examination revealed profound deficits in all cognitive domains and 3T brain MRI showed marked fronto-temporal atrophy. A mutation in the GRN gene further confirmed the diagnosis. Conclusions: The present case documents an unusual onset of bvFTD and highlights the problematic nature of the differential diagnosis between prodromal psychiatric features of the disease and primary psychiatric disorders. Early recognition and diagnosis of bvFTD can lead to appropriate management and support for patients and their families. This case highlights the importance of considering neurodegenerative diseases, such as bvFTD, in the differential diagnosis of psychiatric disorders, especially when exacerbations of behavioral traits manifest in adults.

Nucleus Basalis of Meynert Degeneration Predicts Cognitive Decline in Corticobasal Syndrome.

BACKGROUND: Cognitive changes are common in corticobasal syndrome (CBS) and significantly impact quality of life and caregiver burden. However, relatively few studies have investigated the neural substrates of cognitive changes in CBS, and reliable predictors of cognitive impairment are currently lacking. The nucleus basalis of Meynert (NbM), which serves as the primary source of cortical cholinergic innervation, has been functionally associated with cognition. This study aimed to explore whether patients with CBS exhibit reduced NbM volumes compared with healthy control participants and whether NbM degeneration can serve as a predictor of cognitive impairment in patients with CBS. METHODS: In this study, we investigated in vivo volumetric changes of the NbM in 38 patients with CBS and 84 healthy control participants. Next, we assessed whether gray matter degeneration of the NbM evaluated at baseline could predict cognitive impairment during a 12-month follow-up period in patients with CBS. All volumetric analyses were performed using 3T T1-weighted images obtained from the 4-Repeat Tauopathy Neuroimaging Initiative. RESULTS: Patients with CBS displayed significantly lower NbM volumes than control participants (p < .001). Structural damage of the NbM also predicted the development of cognitive impairment in patients with CBS as assessed by longitudinal measurements of the Clinical Dementia Rating Sum of Boxes (p < .001) and Mini-Mental State Examination (p = .035). CONCLUSIONS: Our findings suggest that NbM atrophy may represent a promising noninvasive in vivo marker of cognitive decline in CBS and provide new insights into the neural mechanisms that underlie cognitive impairment in CBS.

Sleep and circadian rhythm disruptions in behavioral variant frontotemporal dementia.

INTRODUCTION: Sleep and rest-activity rhythm alterations are common in neurodegenerative diseases. However, their characterization in patients with behavioral variant frontotemporal dementia (bvFTD) has proven elusive. We investigated rest-activity rhythm alterations, sleep disturbances, and their neural correlates in bvFTD. METHODS: Twenty-seven bvFTD patients and 25 healthy controls completed sleep questionnaires and underwent 7 days of actigraphy while concurrently maintaining a sleep diary. Cortical complexity and thickness were calculated from T1-weighted magnetic resonance (MR) images. RESULTS: Compared to controls, bvFTD patients showed longer time in bed (95% confidence interval [CI]: 79.31, 321.83) and total sleep time (95% CI: 24.38, 321.88), lower sleep efficiency (95% CI: -12.58, -95.54), and rest-activity rhythm alterations in the morning and early afternoon. Increased sleep duration was associated with reduced cortical thickness in frontal regions. DISCUSSION: Patients with bvFTD showed longer sleep duration, lower sleep quality, and rest-activity rhythm alterations. Actigraphy could serve as a cost-effective and accessible tool for ecologically monitoring changes in sleep duration in bvFTD patients. HIGHLIGHTS: We assessed sleep and circadian rhythms in behavioral variant frontotemporal dementia (bvFTD) using actigraphy. Patients with bvFTD show increased sleep duration and reduced sleep quality. Patients with bvFTD show rest-activity alterations in the morning and early afternoon. Sleep duration is associated with reduced cortical thickness in frontal regions. These alterations may represent an early sign of neurodegeneration.

Cognitive and Neuropathophysiological Outcomes of Gamma-tACS in Dementia: A Systematic Review.

Despite the numerous pharmacological interventions targeting dementia, no disease-modifying therapy is available, and the prognosis remains unfavorable. A promising perspective involves tackling high-frequency gamma-band (> 30 Hz) oscillations involved in hippocampal-mediated memory processes, which are impaired from the early stages of typical Alzheimer's Disease (AD). Particularly, the positive effects of gamma-band entrainment on mouse models of AD have prompted researchers to translate such findings into humans using transcranial alternating current stimulation (tACS), a methodology that allows the entrainment of endogenous cortical oscillations in a frequency-specific manner. This systematic review examines the state-of-the-art on the use of gamma-tACS in Mild Cognitive Impairment (MCI) and dementia patients to shed light on its feasibility, therapeutic impact, and clinical effectiveness. A systematic search from two databases yielded 499 records resulting in 10 included studies and a total of 273 patients. The results were arranged in single-session and multi-session protocols. Most of the studies demonstrated cognitive improvement following gamma-tACS, and some studies showed promising effects of gamma-tACS on neuropathological markers, suggesting the feasibility of gamma-tACS in these patients anyhow far from the strong evidence available for mouse models. Nonetheless, the small number of studies and their wide variability in terms of aims, parameters, and measures, make it difficult to draw firm conclusions. We discuss results and methodological limitations of the studies, proposing possible solutions and future avenues to improve research on the effects of gamma-tACS on dementia.

Reperfusion strategies in stroke with medium-to-distal vessel occlusion: a prospective observational study.

INTRODUCTION: Medium vessel occlusion (MeVO) accounts for 30% of acute ischemic stroke cases. The risk/benefit profile of endovascular thrombectomy (EVT) and intravenous thrombolysis (IVT) or the combination of the two (bridging therapy (BT)) is still unclear in MeVO. Here, we compare reperfusion strategies in MeVO for clinical and radiological outcomes. METHODS: This prospective single center study enrolled consecutive patients with AIS due to primary MeVO undergoing IVT, EVT, or BT at a comprehensive stroke center. Primary outcome was good functional status, defined as modified Rankin Scale (mRS) 0-2 at 3-month follow-up. Additional outcomes included mortality, successful recanalization, defined as mTICI ≥ 2b, stroke severity at discharge, and symptomatic intracerebral hemorrhage (sICH) according to SITS-MOST criteria. Logistic regression was modeled to define independent predictors of the primary outcome. RESULTS: Overall, 180 consecutive people were enrolled (IVT = 59, EVT = 38, BT = 83), mean age 75. BT emerged as independent predictor of primary outcome (OR = 2.76, 95% CI = 1.08-7.07) together with age (OR = 0.94, 95% CI = 0.9-0.97) and baseline NIHSS (OR = 0.88, 95% CI = 0.81-0.95). BT associated with a 20% relative increase in successful recanalization compared to EVT (74.4 vs 56.4%, p = 0.049). Rates of sICH (1.1%) and procedural complications (vasospasm 4.1%, SAH in 1.7%) were very low, with no difference across groups. DISCUSSION: BT may carry a higher chance of good functional outcome compared to EVT/IVT only in people with AIS due to MeVO, with marginally higher rates of successful recanalization. Randomized trials are needed to define optimal treatment tailoring for MeVO.

LAENALS: epidemiological and clinical features of amyotrophic lateral sclerosis in Latin America.

OBJECTIVE: The Latin American Epidemiologic study of ALS (LAENALS) aims to gather data on ALS epidemiology, phenotype, and risk factors in Cuba, Chile, and Uruguay, to understand the impact of genetic and environmental factors on ALS. METHODS: A harmonized data collection protocol was generated, and a Latin-American Spanish language Register was constructed. Patient data were collected in Uruguay in 2018, in Chile from 2017 to 2019, and in Cuba between 2017 and 2018. Statistical analysis was performed using SPSS 25.0.0 software. Crude cumulative incidence, standardized incidence, and prevalence were calculated in the population aged 15 years and older. RESULTS: During 2017-2019, 90 people with ALS from Uruguay (55.6% men), 219 from Chile (54.6% men), and 49 from Cuba (55.1% men) were included. The cumulative crude incidence in 2018 was 1.73/100,000 persons in Uruguay, 1.08 in Chile and 0.195 in Cuba. Crude prevalence in 2018 was 2.19 per 100,000 persons in Uruguay, 1.39 in Chile and 0.55 in Cuba. Mean age at onset was 61.8 ± 11.96 SD years in Uruguay, 61.9 ± 10.4 SD years in Chile, and 60.21 ± 12.45 SD years in Cuba (p = 0.75). Median survival from onset was 32.43 months (21.93 - 42.36) in Uruguay, 24 months (13.5 - 33.5) in Chile, and 29 months (15 - 42.5) in Cuba (p = 0.006). CONCLUSIONS: These preliminary data from LAENALS confirm the lower incidence and prevalence of ALS in counties with admixed populations. The LAENALS database is now open to other Latin American countries for harmonized prospective data collection.

Cohort analysis of novel SPAST variants in SPG4 patients and implementation of in vitro and in vivo studies to identify the pathogenic mechanism caused by splicing mutations.

Introduction: Pure hereditary spastic paraplegia (SPG) type 4 (SPG4) is caused by mutations of SPAST gene. This study aimed to analyze SPAST variants in SPG4 patients to highlight the occurrence of splicing mutations and combine functional studies to assess the relevance of these variants in the molecular mechanisms of the disease. Methods: We performed an NGS panel in 105 patients, in silico analysis for splicing mutations, and in vitro minigene assay. Results and discussion: The NGS panel was applied to screen 105 patients carrying a clinical phenotype corresponding to upper motor neuron syndrome (UMNS), selectively affecting motor control of lower limbs. Pathogenic mutations in SPAST were identified in 12 patients (11.42%), 5 missense, 3 frameshift, and 4 splicing variants. Then, we focused on the patients carrying splicing variants using a combined approach of in silico and in vitro analysis through minigene assay and RNA, if available. For two splicing variants (i.e., c.1245+1G>A and c.1414-2A>T), functional assays confirm the types of molecular alterations suggested by the in silico analysis (loss of exon 9 and exon 12). In contrast, the splicing variant c.1005-1delG differed from what was predicted (skipping exon 7), and the functional study indicates the loss of frame and formation of a premature stop codon. The present study evidenced the high splice variants in SPG4 patients and indicated the relevance of functional assays added to in silico analysis to decipher the pathogenic mechanism.