Associations between sensory impairment and functional limitations among older Chinese adults: mediating roles of social isolation and cognition.

BACKGROUND: The high prevalence of sensory impairment and functional limitations in older adults is a significant concern, yet there is limited understanding of the relationship between these two conditions. Therefore, the objective of this study was to investigate the pathways connecting sensory impairment and functional limitations by examining serial multiple mediating effects of social isolation and cognition in older adults. METHODS: Using the China Health and Retirement Longitudinal Study dataset, a sample of 4871 older adults was selected. The study variables included sensory impairment, functional limitations, social isolation and cognition, and other covariates. A hierarchical multiple linear regression model was used to assess the association between sensory impairment and functional limitations. Mediation analysis was conducted to explore the sequential multiple mediating effects of social isolation and cognitive function in the relationship between sensory impairment and functional limitations. RESULTS: Our findings revealed a significant and positive association between sensory impairment and functional limitations (B = 0.615, 95% CI: 0.397, 0.834). After adjusting for social isolation and cognitive function, the impact of sensory impairment on functional limitations accounted for 87.19% of the total effect. Additionally, approximately 12.81% of the significant relationship between dual sensory impairment and functional limitations was mediated by social isolation and cognitive function. A serial multiple mediating pathway (sensory impairment → social isolation → cognition → functional limitations) was identified, with a coefficient of 0.013 (95% CI: 0.006, 0.020). CONCLUSIONS: Our study provides evidence for the mediating effects of social isolation and cognition in the relationship between sensory impairment and functional limitations. Given the prevalence of functional limitations among older adults with sensory impairment, it is crucial to consider social isolation and cognitive function in efforts to reduce the burden of disability care. Future validation of these findings through longitudinal studies is necessary.

Types of sensory disability are differentially associated with mental health in older US adults over time.

BACKGROUND: Sensory disability in older adults is associated with increased rates of depressive symptoms and loneliness. Here, we examined the impact of hearing, vision, and olfaction disability on mental health outcomes in older US adults. METHODS: We studied respondents from the first three rounds (2005/6, 2010/11, and 2015/16) of the National Social Life, Health and Aging Project, a nationally representative, longitudinal study of older US adults. Sensory function was assessed by structured interviewer ratings (hearing and vision) and objective assessment (olfaction). Cox proportional hazards models and one degree of freedom tests for trend were utilized to analyze the relationships between sensory disability and self-rated mental health, frequent depressive symptoms, frequent perceived stress, frequent anxiety symptoms, and frequent loneliness symptoms over time, adjusting for demographics, health behaviors, comorbidities, and cognitive function. RESULTS: We analyzed data from 3940 respondents over 10 years of follow-up. A greater number of sensory disabilities was associated with greater hazard of low self-rated mental health, frequent depressive symptoms, frequent perceived stress, and frequent loneliness symptoms over time (p ≤ 0.003, all). After adjusting for covariates, older adults with a greater number of sensory disabilities had greater hazard of low self-rated mental health (HR = 1.22, CI = [1.08, 1.38], p = 0.002) and loneliness symptoms (HR = 1.13, CI = [1.05, 1.22], p = 0.003) over time in our tests for trend. In our Cox proportional hazards model, older adults with vision disability had greater hazard of low self-rated mental health (HR = 1.34, 95% CI = [1.05, 1.72], p = 0.02) and loneliness symptoms (HR = 1.21, CI = [1.04, 1.41], p = 0.01). CONCLUSIONS: Older US adults with greater numbers of sensory disabilities face worse subsequent mental health. Future longitudinal studies dissecting the relationship of all five classical senses will be helpful in further understanding how improving sensory function might improve mental health in older adults.

Sensory impairment, loneliness, and the discordance between subjective and objective cognitive function among older adults: A multi-cohort study.

OBJECTIVES: This study aimed to examine the association between sensory impairment and the discordance between subjective/objective cognitive function among older adults and test the mediating effect of loneliness. METHODS: We used data from four cohort studies conducted in 16 countries (N = 19,119). Sensory impairment and subjective cognitive impairment were self-reported. Objective cognitive impairment was measured in three dimensions. Generalized estimating equations were conducted to examine the association between sensory impairment and discordance in subjective/objective cognitive function. Cross-lagged panel model and a bootstrap method with 2,000 samples were employed to verify the mediating effect. RESULTS: Sensory impairment was related to an increased risk of subjective cognitive impairment (OR = 4.70, 95 % CI 4.33-5.10), objective impairment (OR = 1.51, 95 %CI 1.31-1.74), as well as the discordance in subjective/objective cognitive function (OR = 1.35, 95 %CI 1.06-1.71 for older adults with normal subjective cognitive function). In contrast, sensory impairment was associated with a decreased risk of discordant subjective/objective cognitive function among those with subjective cognitive impairment (OR = 0.79, 95 %CI 0.66-0.94). Moreover, loneliness mediated the association between sensory impairment and subjective cognitive impairment (standardized indirect effect = 0.002, 95 %CI 0.001-0.004), objective cognitive impairment (standardized indirect effect = 0.005, 95 %CI 0.003-0.007) as well as the discordance in subjective/objective cognitive function (standardized indirect effect = 0.001, 95 %CI 0.001-0.003 for older adults with normal subjective cognitive function). CONCLUSIONS: Significant association between sensory impairment and discordance in subjective/objective cognitive function and the mediating role of loneliness were revealed, varying by subjective cognitive function. Early screening on sensory impairment and targeted interventions on loneliness should be considered in future policies on cognitive impairment.

Disentangling the relationship between sensory processing, alexithymia and broad autism spectrum: A study in parents' of children with autism spectrum disorders and sensory processing disorders.

BACKGROUND: Autistic features and sensory processing difficulties and their phenotypic co-expression with alexithymia share a transdiagnostic vulnerability. In this work, we explored whether the current concept of broad autism phenotype rather translates altered sensory processing (non-specific to autism), meaning that the characteristics of altered sensory processing should be overexpressed among individuals with heightened vulnerability to sensory processing atypicalities (parents of children with sensorial processing disorder, or SPD parents) and individuals with heightened vulnerability to autistic traits (parents of children with autism spectrum disorders, or ASD parents). In addition, the association between altered sensory processing and alexithymia was inspected. METHOD: The Adolescent/Adult Sensory Profile, Autism Spectrum Quotient, and Toronto Alexithymia Scale were completed by 31 parents of children with ASD, 32 parents of children with SPD, and 52 parents of typically developed (TD) children. RESULTS: Extreme sensory patterns were overexpressed both in parents of children with SPD and parents of children with ASD when compared to parents of TD children. In addition, extreme sensory patterns were significantly associated with alexithymia scores. Specifically, sensory avoidance, low registration, and sensory sensitivity were positively correlated with alexithymia. No significant differences were found regarding the proportion of autistic traits and alexithymia between ASD and SPD groups of parents. CONCLUSIONS: These results challenge the specificity of broad autism phenotype and suggest a neurodevelopmental atypicity with roots in altered sensory and emotional processing.

Prevalence and severity-based classification of sensory processing issues. An exploratory study with neuropsychological implications.

Sensory processing issues, mainly known as sensory processing disorder or SPD, are frequent in children with neurodevelopmental disorders and are associated with learning and behavioral difficulties. However, previous studies suggest that these disturbances might also be present in typically developing children, reaching prevalence rates of 10-20%. Nevertheless, published studies have been primary been conducted in non-European countries. Therefore, we aim, as first objective, to explore the frequency of sensory processing difficulties in a random sample of school-age children from Spain to contribute to the study of its prevalence. The Sensory Profile-2 (SP2) assessment tool was administered to 369 participants to study their sensory processing patterns, the absence or presence of sensory processing issues, the affected sensory systems, as well as their socioemotional, attentional, and behavioral impact. Furthermore, as second objective, we have developed a novel strategy to classify SPD by severity ranges using SP2 yielded results; accordingly, the sample was classified as follows: no alteration, mild, moderate, and severe sensory processing alteration. The results show prevalence rates consistent with previous findings: 15.9% of participants met the severe alteration criteria and 10.5%, 11.1% and 62.5% were classified as moderate, mild and no alteration, respectively. Finally, we hypothesize about SPD and underlying neuropsychological processes that might be associated with this condition. Our results highlight the necessity of further research efforts to establish whether high-frequency and severity rates of sensory processing alterations are linked to neuropsychological variables. The provided classification system might be useful to determine such associations.

Postural and gait symptoms in de novo Parkinson's disease patients correlate with cholinergic white matter pathology.

INTRODUCTION: The postural instability gait difficulty motor subtype of patients with Parkinson's disease (PIGD-PD) has been associated with more severe cognitive pathology and a higher risk on dementia compared to the tremor-dominant subtype (TD-PD). Here, we investigated whether the microstructural integrity of the cholinergic projections from the nucleus basalis of Meynert (NBM) was different between these clinical subtypes. METHODS: Diffusion-weighted imaging data of 98 newly-diagnosed unmedicated PD patients (44 TD-PD and 54 PIGD-PD subjects) and 10 healthy controls, were analysed using diffusion tensor imaging, focusing on the white matter tracts associated with cholinergic projections from the NBM (NBM-WM) as the tract-of-interest. Quantitative tract-based and voxel-based analyses were performed using FA and MD as the estimates of white matter integrity. RESULTS: Voxel-based analyses indicated significantly lower FA in the frontal part of the medial and lateral NBM-WM tract of both hemispheres of PIGD-PD compared to TD-PD. Relative to healthy control, several clusters with significantly lower FA were observed in the frontolateral NBM-WM tract of both disease groups. Furthermore, significant correlations between the severity of the axial and gait impairment and NBM-WM FA and MD were found, which were partially mediated by NBM-WM state on subjects' attentional performance. CONCLUSIONS: The PIGD-PD subtype shows a loss of microstructural integrity of the NBM-WM tract, which suggests that a loss of cholinergic projections in this PD subtype already presents in de novo PD patients.

Self-reported dual sensory impairment, dementia, and functional limitations in Medicare beneficiaries.

BACKGROUND: Vision and hearing impairments often co-exist with dementia, and all are independently associated with limitations in daily activities. Our aim was to examine the association of dual sensory impairment with functional limitations, and further examine the combined estimated association of sensory impairment and dementia with these functional limitations. METHODS: Cross-sectional analysis of the National Health and Aging Trends Study (NHATS), a population-based cohort of Medicare beneficiaries, was performed. Participants were selected from the 2015 round. Survey weighted Poisson regression models adjusted for dementia, demographics, and health status variables examined the association of self-reported dual sensory impairment (no sensory impairment, single sensory impairment, dual sensory impairment) with scores of limitations in mobility, self-care, and household activities. Models were repeated to take into account the combined effects of dual sensory impairment and dementia. RESULTS: Overall, 7124 participants representative of Medicare beneficiaries 65 years or older were included. Of them, 43.9% were 75 years or older and 55.3% were female. Older adults with dual sensory impairment had greater limitations with mobility (prevalence rate ratio [PRR] = 1.45, 95% CI = 1.28-1.63), self-care (PRR = 1.41, 95% CI = 1.25-1.59), and household activities (PRR = 1.54, 95% CI = 1.37-1.72) compared with those without sensory impairment. They also had greater limitations than those with a single sensory impairment across the different activity categories. In models taking into account the combined estimated effect of both sensory impairment and dementia, those with dual sensory impairment and dementia had greater limitations than those without sensory impairment or dementia in each category (mobility: PRR = 1.85, 95% CI = 1.59-2.14, self-care: PRR = 1.86, 95% CI = 1.59-2.18, household: PRR = 2.41, 95% CI = 2.09-2.77). CONCLUSIONS: Older adults with dual sensory impairment had greater functional limitations compared with those without sensory impairment and those with a single sensory impairment. Strategies to improve visual and/or hearing function (e.g., sensory aids, rehabilitation) could potentially help prevent or minimize disability, even among those with dementia.

Ear fullness characteristics and prognosis in patients with all-frequency sudden sensorineural hearing loss.

OBJECTIVE: This study investigated the characteristics and prognosis of the feeling of ear fullness in patients with unilateral all-frequency sudden sensorineural hearing loss. METHODS: Our study included 56 patients with a diagnosis of unilateral all-frequency sudden sensorineural hearing loss accompanied by a feeling of ear fullness and 48 patients without a feeling of ear fullness. The condition of these patients was prospectively observed. RESULTS: Positive correlations were observed between grading of feeling of ear fullness and hearing loss in patients with a feeling of ear fullness (r = 0.599, p < 0.001). No significant differences were observed in the total effective rate of hearing recovery between patients with and without a feeling of ear fullness after one month of treatment (Z = -0.641, p = 0.521). Eighty-six per cent of patients (48 out of 56) showed complete recovery from the feeling of ear fullness. There was no correlation between feeling of ear fullness recovery and hearing recovery (r = 0.040, p = 0.769). CONCLUSION: The prognosis of feeling of ear fullness is good. There was no correlation between feeling of ear fullness recovery and hearing recovery for all-frequency sudden sensorineural hearing loss patients.

Inhibition of TLR4 signaling protects mice from sensory and motor dysfunction in an animal model of autoimmune peripheral neuropathy.

BACKGROUND: While the etiology remains elusive, macrophages and T cells in peripheral nerves are considered as effector cells mediating autoimmune peripheral neuropathy (APN), such as Guillain-Barre syndrome. By recognizing both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) signals, TLRs play a central role in the initiation of both innate and adaptive immune responses. In this study, we aimed to understand the involvement of TLR4 in the pathogenesis of APN and explore the potential of TLR4 as a drug target for therapeutic use. METHODS: APN was induced by a partial ligation on one of the sciatic nerves in B7.2 (L31) transgenic mice which possess a predisposed inflammatory background. APN pathology and neurological function were evaluated on the other non-injured sciatic nerve. RESULTS: TLR4 and its endogenous ligand HMGB1 were highly expressed in L31 mice, in circulating immune cells and in peripheral nerves. Enhanced TLR4 signaling was blocked with TAK 242, a selective TLR4 inhibitor, before and after disease onset. Intraperitoneal administration of TAK 242 not only inhibited monocyte, macrophage and CD8+ T cell activation, but also reduced the release of pro-inflammatory cytokines. TAK 242 protected mice from severe myelin and axonal loss, resulting in a remarkable improvement in mouse motor and sensory functions. TAK 242 was effective in alleviating the disease in both preventive and reversal paradigms. CONCLUSION: The study identified the critical contribution of TLR4-mediated macrophage activation in disease course and provided strong evidence to support TLR4 as a useful drug target for treating inflammatory autoimmune neuropathy.

Chronic Pharmacological Increase of Neuronal Activity Improves Sensory-Motor Dysfunction in Spinal Muscular Atrophy Mice.

Dysfunction of neuronal circuits is an important determinant of neurodegenerative diseases. Synaptic dysfunction, death, and intrinsic activity of neurons are thought to contribute to the demise of normal behavior in the disease state. However, the interplay between these major pathogenic events during disease progression is poorly understood. Spinal muscular atrophy (SMA) is a neurodegenerative disease caused by a deficiency in the ubiquitously expressed protein SMN and is characterized by motor neuron death, skeletal muscle atrophy, as well as dysfunction and loss of both central and peripheral excitatory synapses. These disease hallmarks result in an overall reduction of neuronal activity in the spinal sensory-motor circuit. Here, we show that increasing neuronal activity by chronic treatment with the FDA-approved potassium channel blocker 4-aminopyridine (4-AP) improves motor behavior in both sexes of a severe mouse model of SMA. 4-AP restores neurotransmission and number of proprioceptive synapses and neuromuscular junctions (NMJs), while having no effects on motor neuron death. In addition, 4-AP treatment with pharmacological inhibition of p53-dependent motor neuron death results in additive effects, leading to full correction of sensory-motor circuit pathology and enhanced phenotypic benefit in SMA mice. Our in vivo study reveals that 4-AP-induced increase of neuronal activity restores synaptic connectivity and function in the sensory-motor circuit to improve the SMA motor phenotype.SIGNIFICANCE STATEMENT Spinal muscular atrophy (SMA) is a neurodegenerative disease, characterized by synaptic loss, motor neuron death, and reduced neuronal activity in spinal sensory-motor circuits. However, whether these are parallel or dependent events is unclear. We show here that long-term increase of neuronal activity by the FDA-approved drug 4-aminopyridine (4-AP) rescues the number and function of central and peripheral synapses in a SMA mouse model, resulting in an improvement of the sensory-motor circuit and motor behavior. Combinatorial treatment of pharmacological inhibition of p53, which is responsible for motor neuron death and 4-AP, results in additive beneficial effects on the sensory-motor circuit in SMA. Thus, neuronal activity restores synaptic connections and improves significantly the severe SMA phenotype.