Chronic Respiratory Diseases and Neurodegenerative Disorders: A Primer for the Practicing Clinician

Beyond the lungs: Exploring diverse applications of bromhexine and ambroxol

The respiratory tract is commonly affected in multisystem disorders. Although many drugs have been developed to target various components of these diseases, there is still a need for effective treatments that can address both respiratory and non-respiratory symptoms. Bromhexine and ambroxol are mucolytic agents with a good safety profile that are widely used to treat respiratory conditions. These compounds seem to present several unresolved questions when carrying out their therapeutic effects, suggesting that they may not merely improve mucociliary clearance. These assumptions have provided the basis for researchers to investigate the specific characteristics of bromhexine and ambroxol. This has led to the emergence of several repositionings for this compound. Accordingly, these compounds have also shown potential benefits in the treatment of various extrapulmonary disorders, including neurological disorders, and inflammatory bowel disease. We gathered findings from relevant studies published in English between 1970 and December 2023 by searching databases including PubMed, Google Scholar, Scopus, Embase, and the Cochrane Library. Our findings revealed that most of the research on extrapulmonary uses has been conducted at the preclinical level. Accordingly, more clinical studies are needed to determine the effectiveness of bromhexine and ambroxol in these conditions. This article provides an overview of the potential extrapulmonary applications of bromhexine and ambroxol and discusses the potential advantages of using these drugs in multisystem disorders.

Retinal Nerve Fiber Layer Changes in Patients With Chronic Obstructive Pulmonary Disease Compared to Healthy Controls: A Meta-analysis

BACKGROUND AND OBJECTIVE

This study investigated changes in retinal nerve fiber layers (RNFL) in patients diagnosed with chronic obstructive pulmonary disease (COPD) compared to healthy control patients, using optical coherence tomography.

METHODS

PubMed, Cochrane Library, and Google Scholar databases were systematically searched for published articles comparing RNFL between patients with COPD and healthy controls. Standardized mean difference (SMD) with 95% confidence interval (CI) was computed to compare continuous variables.

RESULTS

Average RNFL thickness was significantly reduced in COPD patients compared to healthy controls (SMD = -0.31, 95% CI = -0.48 to -0.14, P = 0.0004, I2 = 0%). Average RNFL thickness did not differ significantly between patients with mild/moderate COPD and healthy controls (SMD = -0.17, 95% CI = -0.39 to 0.04, P = 0.12, I2 = 2%), while a statistically significant reduction in average RNFL thickness was noticed in patients with severe COPD compared to healthy controls (SMD = -0.72, 95% CI = -1.23 to -0.21, P = 0.006, I2 = 83%). Average RNFL thickness was significantly higher in patients with mild/moderate COPD compared to patients with severe COPD (SMD = 0.69, 95% CI = 0.29 to 1.09, P = 0.0008, I2 = 66%).

CONCLUSIONS

This meta-analysis showed that RNFL thickness was decreased in patients with COPD compared to healthy controls. Patients diagnosed with severe COPD seem to be more affected and have thinner RNFL. [Ophthalmic Surg Lasers Imaging Retina 2024;55:334-342.].

A systematic review and meta-analysis of respiratory dysfunction in Parkinson's disease

INTRODUCTION

Respiratory dysfunction in Parkinson's disease (PD) is common and associated with increased hospital admission and mortality rates. Central and peripheral mechanisms have been proposed in PD. To date no systematic review identifies the extent and type of respiratory impairments in PD compared with healthy controls.

METHODS

PubMed, EMBASE, CINAHL, Web of Science, Pedro, MEDLINE, Cochrane Library and OpenGrey were searched from inception to December 2021 to identify case-control studies reporting respiratory measures in PD and matched controls.

RESULTS

Thirty-nine studies met inclusion criteria, the majority with low risk of bias across Risk of Bias Assessment tool for Non-randomized Studies (RoBANS) domains. Data permitted pooled analysis for 26 distinct respiratory measures. High-to-moderate certainty evidence of impairment in PD was identified for vital capacity (standardised mean difference [SMD] 0.75; 95% CI 0.45-1.05; p < 0.00001; I2  = 10%), total chest wall volume (SMD 0.38; 95% CI 0.09-0.68; p = 0.01; I2  = 0%), maximum inspiratory pressure (SMD 0.91; 95% CI 0.64-1.19; p < 0.00001; I2  = 43%) and sniff nasal inspiratory pressure (SMD 0.58; 95% CI 0.30-0.87; p < 0.00001; I2  = 0%). Sensitivity analysis provided high-moderate certainty evidence of impairment for forced vital capacity and forced expiratory volume in 1 s during medication ON phases and increased respiratory rate during OFF phases. Lower certainty evidence identified impairments in PD for maximum expiratory pressure, tidal volume, maximum voluntary ventilation and peak cough flow.

CONCLUSIONS

Strong evidence supports a restrictive pattern with inspiratory muscle weakness in PD compared with healthy controls. Limited data for central impairment were identified with inconclusive findings.

Shared Molecular Mechanisms among Alzheimer’s Disease, Neurovascular Unit Dysfunction and Vascular Risk Factors: A Narrative Review

Alzheimer’s disease (AD) is the most common type of dementia, affecting 24 million individuals. Clinical and epidemiological studies have found several links between vascular risk factors (VRF), neurovascular unit dysfunction (NVUd), blood-brain barrier breakdown (BBBb) and AD onset and progression in adulthood, suggesting a pathogenetic continuum between AD and vascular dementia. Shared pathways between AD, VRF, and NVUd/BBB have also been found at the molecular level, underlining the strength of this association. The present paper reviewed the literature describing commonly shared molecular pathways between adult-onset AD, VRF, and NVUd/BBBb. Current evidence suggests that VRF and NVUd/BBBb are involved in AD neurovascular and neurodegenerative pathology and share several molecular pathways. This is strongly supportive of the hypothesis that the presence of VRF can at least facilitate AD onset and progression through several mechanisms, including NVUd/BBBb. Moreover, vascular disease and several comorbidities may have a cumulative effect on VRF and worsen the clinical manifestations of AD. Early detection and correction of VRF and vascular disease by improving NVUd/BBBd could be a potential target to reduce the overall incidence and delay cognitive impairment in AD.