Genetic determinants of swallowing impairments among community dwelling older population

Association between the C-reactive protein/albumin ratio and mortality in older Japanese patients with dysphagia

Background

C-reactive protein-to-albumin ratio (CRP/ALB) has been proven to represent a biomarker for predicting prognosis in many groups of patients with severe diseases. However, few studies have investigated the association between CRP/ALB and mortality in Japan older people with dysphagia patients.

Objective

This retrospective cohort study aimed to assess the prognostic value of C-reactive protein/albumin ratio (CAR) in older Japanese patients with dysphagia.

Methods

We analyzed data from 253 patients diagnosed with dysphagia at a single center between January 2014 and January 2017. Cox regression analysis was used to compare the mortality rates across the CAR tertiles. Subgroup analyses were conducted, and Kaplan-Meier curves were used to determine the median survival times.

Results

The study included 154 female and 99 male patients, with a median age of 83 years. After adjusting for all covariates, the multivariable Cox regression analysis revealed a significant association between increasing CAR (HR = 1.19, 95% CI: 1.03-1.37, P = 0.022) and the risk of mortality. Compared to the reference group T1 (< 0.149), the adjusted hazard ratios for T2 (0.149-0.815) and T3 (> 0.815) were 1.75 (95% CI: 1.07-2.87, P = 0.027) and 2.15 (95% CI: 1.34-3.46, P = 0.002), respectively. Kaplan-Meier curves indicated median survival times of 864, 371, and 223 days for T1, T2, and T3, respectively.

Conclusion

The C-reactive protein/albumin ratio was positively related to mortality in Japan older people with dysphagia patients. There was no interaction for the subgroup analysis. The result was stable.

Diagnostic utility of different dysphagia screening tools to detect dysphagia in individuals with amyotrophic lateral sclerosis

OBJECTIVE

Dysphagia is a common and serious clinical symptom of amyotrophic lateral sclerosis (ALS). The study aimed to evaluate the diagnostic utility of four dysphagia screening tools in ALS, including the ALS Functional Rating Scale-Revised (ALSFRS-R) bulbar subscale, water-swallowing test (WST), Eating Assessment Tool-10 (EAT-10) and Sydney Swallow Questionnaire (SSQ).

METHODS

A total of 68 individuals from First Hospital, Shanxi medical university, were recruited in the study. The ALSFRS-R, WST, EAT-10, SSQ and the gold standard video fluoroscopic swallowing study (VFSS) were performed. The Penetration Aspiration Scale (PAS) during VFSS was assessed to identify unsafe swallowing (PAS ≥ 3) and aspiration (PAS ≥ 6). Receiver operator characteristic curve (ROC) analyses were performed to evaluate the accuracy of the 4 tools. Youden index was used to determine the ideal cut-off value for each tool.

RESULTS

Of the patients, 20.59% (14/68) presented unsafety swallowing and 16.18% (11/68) had aspiration. The four tools could effectively identify patients with unsafe swallowing and aspiration. The EAT-10 had the maximum AUC (0.873 and 0.963, respectively) among the tools in the diagnosis of unsafe swallowing and aspiration. To detect unsafe swallowing and aspiration, an EAT-10 score of 6 (sensitivity: 78.6%, specificity: 87.0%) and an EAT-10 score of 8 (sensitivity: 90.9%, specificity: 91.2%), were the most appropriate cut-off points, respectively.

CONCLUSIONS

The ALSFRS-R bulbar subscale, WST, EAT-10, and SSQ could effectively identify unsafe swallowing and aspiration in patients with ALS. Of the four tools, the EAT-10 was relatively accurate, safe, and convenient. Further studies including more patients should be conducted to verify the conclusions.

Combined GWAS and single cell transcriptomics uncover the underlying genes and cell types in disorders of gut-brain interaction

Disorders of gut-brain interaction (DGBIs), formerly known as functional gastrointestinal disorders, are extremely common and historically difficult to manage. This is largely because their cellular and molecular mechanisms have remained poorly understood and understudied. One approach to unravel the molecular underpinnings of complex disorders such as DGBIs is performing genome wide association studies (GWASs). However, due to the heterogenous and non-specific nature of GI symptoms, it has been difficult to accurately classify cases and controls. Thus, to perform reliable studies, we need to access large patient populations which has been difficult to date. Here, we leveraged the UK Biobank (UKBB) database, containing genetic and medical record data of over half a million individuals, to perform GWAS for five DGBI categories: functional chest pain, functional diarrhea, functional dyspepsia, functional dysphagia, and functional fecal incontinence. By applying strict inclusion and exclusion criteria, we resolved patient populations and identified genes significantly associated with each condition. Leveraging multiple human single-cell RNA-sequencing datasets, we found that the disease associated genes were highly expressed in enteric neurons, which innervate and control GI functions. Further expression and association testing-based analyses revealed specific enteric neuron subtypes consistently linked with each DGBI. Furthermore, protein-protein interaction analysis of each of the disease associated genes revealed protein networks specific to each DGBI, including hedgehog signaling for functional chest pain and neuronal function and neurotransmission for functional diarrhea and functional dyspepsia. Finally, through retrospective medical record analysis we found that drugs that inhibit these networks are associated with an increased disease risk, including serine/threonine kinase 32B drugs for functional chest pain, solute carrier organic anion transporter family member 4C1, mitogen-activated protein kinase 6, and dual serine/threonine and tyrosine protein kinase drugs for functional dyspepsia, and serotonin transporter drugs for functional diarrhea. This study presents a robust strategy for uncovering the tissues, cell types, and genes involved in DGBIs, presenting novel predictions of the mechanisms underlying these historically intractable and poorly understood diseases.

Frequency and associated factors for swallowing impairment in community-dwelling older persons: a systematic review and meta-analysis

INTRODUCTION

Swallowing impairment (SI) is an underdiagnosed dysfunction frequently seen as an expected condition of aging. However, SI can lead to health complications and considerable social impact.

METHODS

The objective of this systematic review with meta-analysis was to evaluate the frequency and associated factors with SI in community-dwelling older persons. Searches were performed in 13 electronic databases including MEDLINE and EMBASE (from inception to September 18, 2021). Data extraction and methodological quality assessment of included studies were performed by two independent reviewers. Meta-analysis of proportions with 95% confidence interval (CI) and prediction interval (PI) was used to pool estimates. Subgroup analysis by Country and Assessment Method was performed. General meta-analysis was used to pool measures of association between potential risk factors and SI occurrence (odds ratio [OR] or prevalence ratio [PR]).

RESULTS

The worldwide estimated frequency of SI in community-dwelling older persons was 20.35% (95%CI 16.61-24.68%, 95%PI 4.79-56.45, I² 99%, n = 33,291). This estimation varied across assessment methods and by country. The main factors associated with SI were a dry mouth (OR 8.1, 95%CI 4.9-13.4), oral diadochokinesis (OR 5.3, 95%CI 1.0-27.3), ≥ 80 years old (OR 4.9, 95%CI 2.6-9.2), genetic factor (SNPrs17601696) (OR 4.8, 95%CI 2.7-8.3), and partial dependence (OR 4.3, 95%CI 2.0-9.3). And the main factors associated with SI estimated by PR were dry mouth sensation (PR 4.1, 95%CI 2.6-6.5), oral sensorimotor alteration (PR 2.6, 95%CI 1.4-4.9), osteoporosis (PR 2.51, 95%CI 1.2-5.3), and heart diseases (PR 2.31, 95%CI 1.1-5.0).

CONCLUSION

One in five older adults worldwide are expected to experience SI and factors associated with this underdiagnosed dysfunction included biological and physiological changes related to aging, physical and psychological conditions, and poor oral health. Early assessment is paramount for the prevention of future clinical complications and should be a high priority in health care practices.

Pathogenic Single Nucleotide Polymorphisms on Autophagy-Related Genes

In recent years, the study of single nucleotide polymorphisms (SNPs) has gained increasing importance in biomedical research, as they can either be at the molecular origin of a determined disorder or directly affect the efficiency of a given treatment. In this regard, sequence variations in genes involved in pro-survival cellular pathways are commonly associated with pathologies, as the alteration of these routes compromises cellular homeostasis. This is the case of autophagy, an evolutionarily conserved pathway that counteracts extracellular and intracellular stressors by mediating the turnover of cytosolic components through lysosomal degradation. Accordingly, autophagy dysregulation has been extensively described in a wide range of human pathologies, including cancer, neurodegeneration, or inflammatory alterations. Thus, it is not surprising that pathogenic gene variants in genes encoding crucial effectors of the autophagosome/lysosome axis are increasingly being identified. In this review, we present a comprehensive list of clinically relevant SNPs in autophagy-related genes, highlighting the scope and relevance of autophagy alterations in human disease.

Genetic influences on the variability of response to repetitive transcranial magnetic stimulation in human pharyngeal motor cortex

BACKGROUND

Recent studies have reported substantial variability in response to repetitive transcranial magnetic stimulation (rTMS). We hypothesized that an individual's genetic predisposition may contribute to such variability in the pharyngeal motor cortex. This study aimed to investigate the response to 1 and 5 Hz rTMS paradigms on pharyngeal motor cortex in healthy participants and its relationship with genetic predisposition.

METHODS

Forty-one healthy participants (25.4 ± 4.6 years old) received either or both 1 Hz (n = 39) and 5 Hz rTMS (n = 40) over pharyngeal motor cortex. Pharyngeal and thenar motor-evoked potentials were recorded at baseline and for 1 hour post-rTMS. The participants were then classified according to their response. The associations between rTMS response and gender, time of day of the stimulation, and eight prespecified single nucleotide polymorphisms (SNPs) were analyzed.

KEY RESULTS

There was no direction-specific response to either paradigm (1 Hz: F[3.69, 129.21] = 0.78, P = 0.56; 5 Hz: F[4.08, 146.85] = 1.38, P = 0.25). Only 13% of participants showed the expected bidirectional response (inhibition for 1 Hz and excitation for 5 Hz). Significant associations were found between response and COMT (1 Hz: P = 0.03) and DRD2 (1 Hz: P = 0.02; 5 Hz: P = 0.04) polymorphisms. Carriers of minor allele G from SNP rs6269 (COMT) were more likely to show inhibitory or excitatory outcomes after 1 Hz rTMS. By contrast, carriers of minor allele A from SNP rs1800497 (DRD2) were more likely to show no response to 1 Hz rTMS and inhibition after 5 Hz rTMS.

CONCLUSIONS & INFERENCES

Two SNPs from COMT and DRD2 genes may partially explain the response variability to rTMS in the pharyngeal motor system. Further research should focus on stratified approaches for neurostimulatory dysphagia treatment using rTMS.

Genetic determinants of swallowing impairment, recovery and responsiveness to treatment

Purpose of review

Here we review the latest literature and evidence in the field of genetics and determinants of swallowing and its treatments—specifically, this is a very recent concept in the field of oropharyngeal dysphagia, with only now an emerging research interest in the relationship between our genetic makeup and the effect this has on swallowing function and dysfunction. As such our review will look at preclinical, clinical and hypothesis generating research covering all aspects of the genetics of swallowing, giving new importance to the genotype-phenotype influences pertaining to dysphagia and its recovery.

Recent findings

There appear to be a number of candidate gene systems that interact with swallowing or its neurophysiology, which include brain-derived neurotrophic factor, apolipoprotein E and catechol-O-methyltransferase, that have been shown to impact on either swallowing function or the brain’s ability to respond to neurostimulation and induce plasticity. In addition, a number of genetic disorders, where dysphagia is a clinical phenomenon, have given us clues as to how multiple genes or the polygenetics of dysphagia might interact with our swallowing phenotype.

Summary

There is currently limited research in the field of genetic factors that influence (human) swallowing and oropharyngeal dysphagia, but this is an emerging science and one which, in the future, may herald a new era in precision medicine and better targeting of therapies for dysphagia based on an individual’s genetic makeup.

High-frequency focal repetitive cerebellar stimulation induces prolonged increases in human pharyngeal motor cortex excitability

KEY POINTS

Neurostimulation is a rapidly emerging approach to swallowing rehabilitation, but cerebellar stimulation has not been explored as a treatment. Such proposed therapies for post-stroke dysphagia have required confirmation of physiological effects and optimisation of parameters in healthy humans prior to translational progression into patient groups. There is strong evidence for a role of the cerebellum in swallowing physiology, but this relationship has been under-explored. Recently, single pulses of cerebellar magnetic stimulation have been shown to directly evoke responses from pharyngeal musculature and produce short-term enhancement of cortico-pharyngeal motor evoked potentials, suggesting the feasibility of a cerebellar approach to neurostimulation in the swallowing system. We therefore examined multiple parameters of repetitive cerebellar magnetic stimulation and have described the optimal settings to provoke longer-lasting changes in swallowing neurophysiology. Based on evidence from the post-stroke dysphagia neurostimulation literature, these changes may have a therapeutic potential for swallowing rehabilitation.

ABSTRACT

Brain neurostimulation has been shown to modulate cortical swallowing neurophysiology in post-stroke dysphagia with therapeutic effects which are critically dependent on the stimulation parameters. Cerebellar neurostimulation is, however, a novel, unexplored approach to modulation of swallowing pathways as a prelude to therapy for dysphagia. Here, we randomised healthy human subjects (n = 17) to receive one of five cerebellar repetitive TMS (rTMS) interventions (Sham, 1 Hz, 5 Hz, 10 Hz and 20 Hz) on separate visits to our laboratory. Additionally, a subset of subjects randomly received each of three different durations (50, 250, 500 pulses) of optimal frequency versus sham cerebellar rTMS. Prior to interventions subjects underwent MRI-guided single-pulse transcranial magnetic stimulation (TMS) to co-localise pharyngeal and thenar representation in the cortex and cerebellum (midline and hemispheric) before acquisition of baseline motor evoked potential (MEP) recordings from each site as a measure of excitability. Post-interventional MEPs were recorded for an hour and compared to sham using repeated measures ANOVA. Only 10 Hz cerebellar rTMS increased cortico-pharyngeal MEP amplitudes (mean bilateral increase 52%, P = 0.007) with effects lasting 30 min post-intervention with an optimal train length of 250 pulses (P = 0.019). These optimised parameters of cerebellar rTMS can produce sustained increases in corticobulbar excitability and may have clinical translation in future studies of neurogenic dysphagia.