Potential Role of the Retrotrapezoid Nucleus in Mediating Cardio-Respiratory Dysfunction in Heart Failure With Preserved Ejection Fraction

Dyspnea in Parkinson's disease

BACKGROUND

Dyspnea is an important non-motor symptom in Parkinson's disease (PD) that impacts quality of life. The mechanisms underlying dyspnea have been difficult to determine due to challenges separating central respiratory control abnormalities from peripheral respiratory muscle dysfunction and chest wall rigidity.

METHODS

A comprehensive literature review was conducted, searching the PubMed database for observational studies on respiratory dysfunction and dyspnea in PD. Inclusion criteria were studies with PD patients without other neurological disorders. Case studies were excluded. Data on study size, disease duration, control groups, and respiratory defects were extracted.

RESULTS

The search yielded 23 unique publications on pulmonary function in PD. Key findings were: 1) restrictive defects are common, with prevalence up to 85 % in some studies; 2) effects of levodopa on pulmonary function are variable across studies; 3) there is limited research on the role of central respiratory centers in dyspnea pathophysiology in PD. Proposed mechanisms include direct involvement of brainstem respiratory structures, loss of dopamine input to these regions, and astrocyte dysfunction affecting respiratory rhythm generation.

CONCLUSION

This review outlines potential mechanisms underlying dyspnea in PD, including central respiratory dysfunction, peripheral muscle/chest wall abnormalities, impaired respiratory sensation, and medication effects. More research is needed investigating specific brainstem regions involved, chemoreceptor pathology, correlations between respiratory load and perceived dyspnea, and medication effects on pulmonary function.

Autonomic nervous system dysfunction throughout menopausal transition: A potential mechanism underpinning cardiovascular and cognitive alterations during female ageing

Cardiovascular diseases (CVD) and neurodegenerative disorders, such as Alzheimer's disease (AD), are highly prevalent conditions in middle-aged women that severely impair quality of life. Recent evidence suggests the existence of an intimate cross-talk between the heart and the brain, resulting from a complex network of neurohumoral circuits. From a pathophysiological perspective, the higher prevalence of AD in women may be explained, at least in part, by sex-related differences in the incidence/prevalence of CVD. Notably, the autonomic nervous system, the main heart-brain axis physiological orchestrator, has been suggested to play a role in the incidence of adverse cardiovascular events in middle-aged women because of decreases in oestrogen-related signalling during transition into menopause. Despite its overt relevance for public health, this hypothesis has not been thoroughly tested. Accordingly, in this review, we aim to provide up to date evidence supporting how changes in circulating oestrogen levels during transition to menopause may trigger autonomic dysfunction, thus promoting cardiovascular and cognitive decline in women. A main focus on the effects of oestrogen-mediated signalling at CNS structures related to autonomic regulation is provided, particularly on the role of oestrogens in sympathoexcitation. Improving the understanding of the contribution of the autonomic nervous system on the development, maintenance and/or progression of both cardiovascular and cognitive dysfunction during the transition to menopause should help improve the clinical management of elderly women, with the outcome being an improved life quality during the natural ageing process.

Sleep dysregulation in sympathetic-mediated diseases: implications for disease progression

The autonomic nervous system (ANS) plays an important role in the coordination of several physiological functions including sleep/wake process. Significant changes in ANS activity occur during wake-to-sleep transition maintaining the adequate cardiorespiratory regulation and brain activity. Since sleep is a complex homeostatic function, partly regulated by the ANS, it is not surprising that sleep disruption trigger and/or evidence symptoms of ANS impairment. Indeed, several studies suggest a bidirectional relationship between impaired ANS function (i.e. enhanced sympathetic drive), and the emergence/development of sleep disorders. Furthermore, several epidemiological studies described a strong association between sympathetic-mediated diseases and the development and maintenance of sleep disorders resulting in a vicious cycle with adverse outcomes and increased mortality risk. However, which and how the sleep/wake control and ANS circuitry becomes affected during the progression of ANS-related diseases remains poorly understood. Thus, understanding the physiological mechanisms underpinning sleep/wake-dependent sympathetic modulation could provide insights into diseases involving autonomic dysfunction. The purpose of this review is to explore potential neural mechanisms involved in both the onset/maintenance of sympathetic-mediated diseases (Rett syndrome, congenital central hypoventilation syndrome, obstructive sleep apnoea, type 2 diabetes, obesity, heart failure, hypertension, and neurodegenerative diseases) and their plausible contribution to the generation of sleep disorders in order to review evidence that may serve to establish a causal link between sleep disorders and heightened sympathetic activity.