Physical and cognitive fitness in young adulthood and risk of amyotrophic lateral sclerosis at an early age

Brain working memory network indices as landmarks of intelligence

Identifying the neural correlates of intelligence has long been a goal in neuroscience. Recently, the field of network neuroscience has attracted researchers' attention as a means for answering this question. In network neuroscience, the brain is considered as an integrated system whose systematic properties provide profound insights into health and behavioral outcomes. However, most network studies of intelligence have used univariate methods to investigate topological network measures, with their focus limited to a few measures. Furthermore, most studies have focused on resting state networks despite the fact that brain activation during working memory tasks has been linked to intelligence. Finally, the literature is still missing an investigation of the association between network assortativity and intelligence. To address these issues, here we employ a recently developed mixed-modeling framework for analyzing multi-task brain networks to elucidate the most critical working memory task network topological properties corresponding to individuals' intelligence differences. We used a data set of 379 subjects (22-35 y/o) from the Human Connectome Project (HCP). Each subject's data included composite intelligence scores, and fMRI during resting state and a 2-back working memory task. Following comprehensive quality control and preprocessing of the minimally preprocessed fMRI data, we extracted a set of the main topological network features, including global efficiency, degree, leverage centrality, modularity, and clustering coefficient. The estimated network features and subject's confounders were then incorporated into the multi-task mixed-modeling framework to investigate how brain network changes between working memory and resting state relate to intelligence score. Our results indicate that the general intelligence score (cognitive composite score) is associated with a change in the relationship between connection strength and multiple network topological properties, including global efficiency, leverage centrality, and degree difference during working memory as it is compared to resting state. More specifically, we observed a higher increase in the positive association between global efficiency and connection strength for the high intelligence group when they switch from resting state to working memory. The strong connections might form superhighways for a more efficient global flow of information through the brain network. Furthermore, we found an increase in the negative association between degree difference and leverage centrality with connection strength during working memory tasks for the high intelligence group. These indicate higher network resilience and assortativity along with higher circuit-specific information flow during working memory for those with a higher intelligence score. Although the exact neurobiological implications of our results are speculative at this point, our results provide evidence for the significant association of intelligence with hallmark properties of brain networks during working memory.

Examining later-in-life health risks associated with sport-related concussion and repetitive head impacts: a systematic review of case-control and cohort studies

OBJECTIVE

Concern exists about possible problems with later-in-life brain health, such as cognitive impairment, mental health problems and neurological diseases, in former athletes. We examined the future risk for adverse health effects associated with sport-related concussion, or exposure to repetitive head impacts, in former athletes.

DESIGN

Systematic review.

DATA SOURCES

Search of MEDLINE, Embase, Cochrane, CINAHL Plus and SPORTDiscus in October 2019 and updated in March 2022.

ELIGIBILITY CRITERIA

Studies measuring future risk (cohort studies) or approximating that risk (case-control studies).

RESULTS

Ten studies of former amateur athletes and 18 studies of former professional athletes were included. No postmortem neuropathology studies or neuroimaging studies met criteria for inclusion. Depression was examined in five studies in former amateur athletes, none identifying an increased risk. Nine studies examined suicidality or suicide as a manner of death, and none found an association with increased risk. Some studies comparing professional athletes with the general population reported associations between sports participation and dementia or amyotrophic lateral sclerosis (ALS) as a cause of death. Most did not control for potential confounding factors (eg, genetic, demographic, health-related or environmental), were ecological in design and had high risk of bias.

CONCLUSION

Evidence does not support an increased risk of mental health or neurological diseases in former amateur athletes with exposure to repetitive head impacts. Some studies in former professional athletes suggest an increased risk of neurological disorders such as ALS and dementia; these findings need to be confirmed in higher quality studies with better control of confounding factors.

PROSPERO REGISTRATION NUMBER

CRD42022159486.

Gut microbiome and amyotrophic lateral sclerosis: A systematic review of current evidence

Amyotrophic lateral sclerosis (ALS), characterized by a loss of motor neurons in the brain and spinal cord, is a relatively rare but currently incurable neurodegenerative disease. The global incidence of ALS is estimated as 1.75 per 100,000 person-years and the global prevalence is estimated as 4.1-8.4 per 100,000 individuals. Contributions from outside the central nervous system to the etiology of ALS have been increasingly recognized. Gut microbiome is one of the most quickly growing fields of research for ALS. In this article, we performed a comprehensive review of the results from existing animal and human studies, to provide an up-to-date summary of the current research on gut microbiome and ALS. In brief, we found relatively consistent results from animal studies, suggesting an altered gut microbiome composition in experimental ALS. Publication bias might however be a concern. Findings from human studies are largely inconclusive. A few animal and human studies demonstrated the usefulness of intervention with microbial-derived metabolites in modulating the disease progression of ALS. We discussed potential methodological concerns in these studies, including study design, statistical power, handling process of biospecimens and sequencing data, as well as statistical methods and interpretation of results. Finally, we made a few proposals for continued microbiome research in ALS, with the aim to provide valid, reproducible, and translatable findings.

Current Views on the Role of Stress in the Pathogenesis of Chronic Neurodegenerative Diseases

The review summarizes the results of studies on the cellular and molecular mechanisms mediating the impact of stress on the pathogenesis of neurodegenerative brain pathologies (Alzheimer's disease, Parkinson's disease, etc.) and presents current information on the role of stress in the hyperphosphorylation of tau protein, aggregation of beta-amyloid, and hyperactivation of the hypothalamic-pituitary-adrenal axis involved in the hyperproduction of factors that contribute to the pathogenetic role of stress in neurodegeneration. The data on the participation of microglia in the effects of stress on the pathogenesis of neurodegenerative diseases are presented.

Polygenic risk score analysis for amyotrophic lateral sclerosis leveraging cognitive performance, educational attainment and schizophrenia

Amyotrophic Lateral Sclerosis (ALS) is recognised to be a complex neurodegenerative disease involving both genetic and non-genetic risk factors. The underlying causes and risk factors for the majority of cases remain unknown; however, ever-larger genetic data studies and methodologies promise an enhanced understanding. Recent analyses using published summary statistics from the largest ALS genome-wide association study (GWAS) (20,806 ALS cases and 59,804 healthy controls) identified that schizophrenia (SCZ), cognitive performance (CP) and educational attainment (EA) related traits were genetically correlated with ALS. To provide additional evidence for these correlations, we built single and multi-trait genetic predictors using GWAS summary statistics for ALS and these traits, (SCZ, CP, EA) in an independent Australian cohort (846 ALS cases and 665 healthy controls). We compared methods for generating the risk predictors and found that the combination of traits improved the prediction (Nagelkerke-R²) of the case-control logistic regression. The combination of ALS, SCZ, CP, and EA, using the SBayesR predictor method gave the highest prediction (Nagelkerke-R²) of 0.027 (P value = 4.6 × 10^-8), with the odds-ratio for estimated disease risk between the highest and lowest deciles of individuals being 3.15 (95% CI 1.96-5.05). These results support the genetic correlation between ALS, SCZ, CP and EA providing a better understanding of the complexity of ALS.

Diabetes mellitus is associated with a lower risk of amyotrophic lateral sclerosis: A systematic review and meta-analysis

BACKGROUND/AIMS

Previous studies have suggested that diabetes mellitus (DM) could be a protective factor against amyotrophic lateral sclerosis (ALS) although the results are inconsistent. This study aimed to comprehensively investigate this relationship by identifying all available studies and summarizing their results.

METHODS

A systematic review was conducted in MEDLINE and EMBASE database from inception to January 1st, 2020 to identify cohort studies and case-control studies that investigated the risk of development of ALS among patients with DM versus individuals without DM. Point estimates and standard errors from eligible studies were pooled together using the generic inverse variance method, as described by DerSimonian and Laird. Visualization of the funnel plot was used to assess for the presence of publication bias.

RESULTS

A total of 1683 articles were identified by the search strategy. After two rounds of review, three cohort studies and eight case-control studies fulfilled the inclusion criteria and were included in the meta-analysis. The risk of developing ALS was significantly lower among patients with DM than individuals without DM with the pooled relative risk of 0.68 (95 % CI, 0.55 - 0.84; I² 81 %). The funnel plot was relatively symmetric and was not suggestive of the presence of publication bias.

CONCLUSION

A significantly decreased risk of ALS among patients with DM was observed in this meta-analysis.

Stress and neurodegeneration

Neurodegenerative diseases are a great concern because of aging worldwide population. Despite substantial effort to advance our understanding of the etiology and potential treatment of neurodegeneration, there remains a paucity of information with respect to this complex disease process. Interestingly, stress has been implicated among the potential mechanisms implicated in neurodegenerative pathology. Given the increase in chronic stress in modern society, this premise warrants further investigation. The aim of this review is to evaluate the influence of stress on neurodegeneration, the effect of neurodegenerative diseases diagnosis on stress, and therapeutic strategies for neurodegenerative diseases with a special focus on stress reduction. Neurodegenerative disorders such as Alzheimer's, Parkinson's and Huntington's Disease showed an acceleration in disease progression and a worsening of symptoms under stress. Some therapies (e.g., yoga, meditation) focused on reducing stress showed beneficial effects against neurodegeneration. Nevertheless, more studies are necessary in order to completely understand the implications of stress in neurodegeneration and the usefulness of stress reduction in the treatment thereof.

Finding diseases associated with amyotrophic lateral sclerosis: a total population-based case-control study

OBJECTIVE

To investigate diseases associated with amyotrophic lateral sclerosis (ALS) by using a total population-based medical database.

METHODS

This study included 705 ALS patients aged older than 15 years diagnosed from January 1, 2007, to December 31, 2013, along with 14,100 controls matching in sex, age, residence, and insurance premium. Data from the National Health Insurance Research Database (NHIRD) and Serious Disabling Diseases (SDD) database in Taiwan were used to conduct a total population-based case-control study. Prior diseases were categorized as being diagnosed 1, 3, 5, 7, or 9 years before first ALS diagnosis. Chi-square or t test was used to examine differences in demographic characteristics between the new patients with ALS and controls. Previous diseases were screened using a conditional logistic regression model. Multivariate analysis was performed using stepwise selection to evaluate the association between these diseases and the risk of ALS. The path analysis was conducted to analyze the pathway between prior diseases and ALS.

RESULTS

In total, 28 diseases were associated with ALS, including 17 positive associations and 11 negative associations. The path analysis revealed that the 11 negatively associated diseases could be attributed to diabetes mellitus and its comorbidities. The 17 positively associated diseases could be categorized as metabolic syndrome, neuroinflammation, head trauma, sports injuries, infections, and their comorbidities.

CONCLUSIONS

Our results support the hypothesis that diseases developing prior to ALS diagnoses are hypermetabolic disorders. Hypometabolic disorders may have a beneficial effect on ALS incidence. Defective energy metabolism may play a role in ALS pathogenesis.

Body mass index and survival from amyotrophic lateral sclerosis: A meta-analysis

Background

Several studies have examined the relationship between body mass index (BMI) and survival from amyotrophic lateral sclerosis (ALS). Many indicate that low BMI at diagnosis or during follow-up may be associated with accelerated progression and shortened survival. This study systematically evaluated the relationship between BMI and survival in patients with ALS.

Methods

The PubMed database was searched to identify all available studies reporting time-to-event data. Eight studies with 6,098 patients fulfilled the eligibility criteria. BMI was considered a continuous and ordered variable. Interstudy heterogeneity was assessed by the Cochran Q test and quantified by the I² metric. Fixed- or random-effects odds ratios summarized pooled effects after taking interstudy variability into account. Significance was set at p < 0.05.

Results

The ALS survival hazard ratio (HR) decreased approximately by 3% (95% confidence interval [CI]: 2%-5%) for each additional BMI unit when BMI was considered a continuous variable. When BMI was considered a categorical variable, the HRs for "normal" BMI vs "overweight" BMI and "obese" BMI were estimated to be as high as 0.91 (95% CI: 0.79-1.04) and 0.78 (95% CI: 0.60-1.01), respectively. The HR for the comparison of the "normal" BMI vs "underweight" BMI was estimated to be as high as 1.94 (95% CI: 1.42-2.65).

Conclusions

BMI is significantly and inversely associated with ALS survival.

Lack of an association between attention-deficit/hyperactivity disorder (ADHD) and amyotrophic lateral sclerosis (ALS)

BACKGROUND

Lulé, Ludolph, and Ludolph (2008) hypothesized that there may be a pathophysiological link between attention-deficit/hyperactivity disorder (ADHD) and amyotrophic lateral sclerosis (ALS). They summarized common clinical features, specifically enhanced physical and psychological activity, which have been described typically for ADHD patients and also as common personality traits before disease onset in patients with ALS.

METHODS

We assessed the lifetime prevalence rate of ADHD in 104 patients with ALS using valid self-report instruments for ADHD symptoms in childhood (WURS-k) and adulthood (ADHD-SB). Results were compared with a population-based sample (n=2069) and with patients with Parkinson's disease (PD, n=52) using regression analyses and adjusting for sociodemographic differences. Physical activity was assessed by the 21-item exercise dependency scale (EDS-21).

RESULTS

ALS patients reported a lower prevalence of childhood ADHD compared to the general population. Both clinical groups reported significantly lower scores on the WURS-k scale and the attention deficit subscale of the ADHD-SB. The EDS-21 showed significantly longer exercise times in ALS and PD patients.

CONCLUSIONS

We could not show that ADHD is more common in ALS patients. However, our results revealed shared personality traits in ALS and PD with lower rates of premorbid attention deficit symptoms and increased physical activity.

Risk factors in Swedish young men for amyotrophic lateral sclerosis in adulthood

Recent research suggests that the incidence of amyotrophic lateral sclerosis (ALS) may be on the rise. Since ALS becomes predominant in later life, most studies on causal factors are conducted in middle-aged or older populations where potentially important influences from early life can usually not be adequately captured. We aimed to investigate predictors in young Swedish men for ALS in adulthood. Therefore, we performed a prospective cohort study of young men (aged 16-25, n = 1,819,817) who enlisted 1968-2005 and took part in comprehensive conscription examinations. Incident cases of ALS (n = 526) during up to 46 years of follow-up were identified in the National Hospital Register and Swedish Cause of Death Register. Those who developed ALS had lower BMI (body mass index) at conscription than their peers (p = 0.03). The risk of ALS during follow-up was calculated with Cox proportional hazards models. No associations were found with physical fitness, erythrocyte sedimentation rate, or non-psychotic mental disorders. Low overall muscle strength compared to high overall muscle strength [hazard ratio (HR) 1.36; 95% confidence interval (CI) 1.01-1.83] and low BMI (a one-unit increase HR 0.96; 95% CI 0.93-0.99) and lower erythrocyte volume fraction (a one-unit increase HR 0.96; 95% CI 0.92-0.998) were the statistically significant predictors for ALS in adjusted models. These findings provide novel epidemiologic evidence of a prospective association between low overall muscle strength and erythrocyte volume fraction in young men and ALS risk.