Absence of alterations in serum sex hormone levels in idiopathic REM sleep behavior disorder

Association of Sleep Duration With Serum Estradiol Concentrations Among American Men and Women: Evidence From NHANES 2013-2016

Objective: To evaluate the association between sleep duration with serum estradiol concentrations and its variation by sex and age in American adults. Methods: Data were analyzed for 5406 men and women (≥ 20 years old) who participated in the cycles of the National Health and Nutrition Examination Survey 2013-2016, a cross-sectional study. Total estradiol (pg/mL) was measured and categorized (low, normal, and high) based on the NHANES protocol. Sleep duration was classified as ≤ 6, 6-9, and ≥ 9 h. Weighted multivariable adjusted and multinomial logistic regression models were conducted to assess these associations. Results: Our multivariable multinomial logistic regression analysis revealed no significant associations between sleep duration and serum estradiol concentrations among both American men and women. Specifically, comparisons of sleep durations (≤ 6 and ≥ 9 h) to the reference group (6-9 h) across various age categories showed odds ratios for low and high estradiol concentrations that remained statistically nonsignificant in fully adjusted models. These findings suggest that, unlike previous studies linking sleep duration with variations in other hormones, estradiol concentrations do not appear to be significantly affected by differences in sleep duration in either sex across all age groups studied. Conclusion: The lack of significant associations between sleep duration and serum estradiol concentrations indicates that sleep duration may not influence estradiol levels in the general population of American men and women. These results underscore the importance of continued research into how sleep influences hormonal balance. However, it is important to note that the NHANES data we used are from a cross-sectional study, which cannot establish a causal relationship between sleep duration and serum estradiol. Future studies should investigate additional factors, such as genetic predispositions, lifestyle habits, and environmental influences, that may modulate the relationship between sleep and hormone levels.

High bioavailable testosterone levels increase the incidence of isolated REM sleep behavior disorder: Results from multivariable and network Mendelian randomization analysis

OBJECTIVES

To explore the causal relationships between sex hormone levels and incidence of isolated REM sleep behavior disorder (iRBD).

METHODS

In our study, we utilized Genome-Wide Association Studies (GWAS) data for iRBD, including 9447 samples with 1061 cases of iRBD provided by the International RBD Study Group. Initially, we conducted a two-sample univariate MR analysis to explore the impact of sex hormone-related indicators on iRBD. This was followed by the application of multivariable MR methods to adjust for other hormone levels and potential confounders. Finally, we undertook a network MR analysis, employing brain structure Magnetic Resonance Imaging (MRI) characteristics as potential mediators, to examine whether sex hormones could indirectly influence the incidence of iRBD by affecting brain structure.

RESULTS

Bioavailable testosterone (BioT) is an independent risk factor for iRBD (Odds Ratio [95 % Confidence Interval] = 2.437 [1.308, 4.539], P = 0.005, corrected-P = 0.020), a finding that remained consistent even after adjusting for other sex hormone levels and potential confounders. Additionally, BioT appears to indirectly increase the risk of iRBD by reducing axial diffusivity and increasing the orientation dispersion index in the left cingulum and cingulate gyrus.

CONCLUSIONS

Our research reveals that elevated levels of BioT contribute to the development of iRBD. However, the specific impact of BioT on different sexes remains unclear. Furthermore, high BioT may indirectly lead to iRBD by impairing normal pathways in the left cingulum and cingulate gyrus and fostering abnormal pathway formation.

Sex differences in rapid eye movement sleep behavior disorder: A systematic review and meta-analysis

Although rapid eye movement (REM) sleep behavior disorder (RBD) has been widely considered as a male-predominant parasomnia, the existing evidence for the sex difference in the risk of RBD in the general population was conflicting. The present study conducted a systematic review to explore the sex differences in the prevalence, comorbidities, clinical characteristics, and phenoconversion of RBD. One hundred thirty-five eligible studies were identified for the systematic review, and 133 were finally included in the meta-analysis. Males in the general population showed a trend for a higher risk of probable/possible RBD (pRBD), especially among the male older adults (aged ≥60). In the clinical populations, males showed a significantly higher risk of confirmed RBD, but not of pRBD. Among idiopathic RBD (iRBD) patients, males had a significantly earlier age onset of RBD compared with females. Male patients with Parkinson's disease (PD) had a higher risk of comorbid RBD. There was no significant sex difference in the risk of developing neurodegenerative diseases in iRBD patients. Large scale and prospective studies utilizing stringent diagnostic criteria for RBD are recommended to further verify the sex differences in RBD and to investigate the mechanism underlying the sex difference.

Sex differences in alpha-synucleinopathies: a systematic review

Background

Past research indicates a higher prevalence, incidence, and severe clinical manifestations of alpha-synucleinopathies in men, leading to a suggestion of neuroprotective properties of female sex hormones (especially estrogen). The potential pathomechanisms of any such effect on alpha-synucleinopathies, however, are far from understood. With that aim, we undertook to systematically review, and to critically assess, contemporary evidence on sex and gender differences in alpha-synucleinopathies using a bench-to-bedside approach.

Methods

In this systematic review, studies investigating sex and gender differences in alpha-synucleinopathies (Rapid Eye Movement (REM) Behavior Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) from 2012 to 2022 were identified using electronic database searches of PubMed, Embase and Ovid.

Results

One hundred sixty-two studies were included; 5 RBD, 6 MSA, 20 DLB and 131 PD studies. Overall, there is conclusive evidence to suggest sex-and gender-specific manifestation in demographics, biomarkers, genetics, clinical features, interventions, and quality of life in alpha-synucleinopathies. Only limited data exists on the effects of distinct sex hormones, with majority of studies concentrating on estrogen and its speculated neuroprotective effects.

Conclusion

Future studies disentangling the underlying sex-specific mechanisms of alpha-synucleinopathies are urgently needed in order to enable novel sex-specific therapeutics.

Neurochemical Features of Rem Sleep Behaviour Disorder

Dopaminergic deficiency, shown by many studies using functional neuroimaging with Single Photon Emission Computerized Tomography (SPECT) and Positron Emission Tomography (PET), is the most consistent neurochemical feature of rapid eye movement (REM) sleep behaviour disorder (RBD) and, together with transcranial ultrasonography, and determination of alpha-synuclein in certain tissues, should be considered as a reliable marker for the phenoconversion of idiopathic RBD (iRBD) to a synucleopathy (Parkinson’s disease –PD- or Lewy body dementia -LBD). The possible role in the pathogenesis of RBD of other neurotransmitters such as noradrenaline, acetylcholine, and excitatory and inhibitory neurotransmitters; hormones such as melatonin, and proinflammatory factors have also been suggested by recent reports. In general, brain perfusion and brain glucose metabolism studies have shown patterns resembling partially those of PD and LBD. Finally, the results of structural and functional MRI suggest the presence of structural changes in deep gray matter nuclei, cortical gray matter atrophy, and alterations in the functional connectivity within the basal ganglia, the cortico-striatal, and the cortico-cortical networks, but they should be considered as preliminary.

Three Decades of Progress in Sleep Disorders and Sleep Health for Women

Over the past 3 decades, significant strides have been made in the field of sleep medicine for women. The impact of sex and gender on sleep health and sleep disorders received little attention in the early 1990s, but driven by policies ensuring inclusion of women in medical research, more recent studies have identified sex differences in sleep and investigated gender differences in sleep disorders. Nevertheless, disparities remain: diagnosis of sleep disorders, such as obstructive sleep apnea, narcolepsy, and rapid eye movement (REM) sleep behavior disorder are often delayed and underdiagnosed in women. Future research should continue to examine how biological sex and identity across the gender spectrum influence sleep health and sleep disorders, allowing for more personalized health care for all patients.

Idiopathic rapid eye movement sleep behaviour disorder: diagnosis, management, and the need for neuroprotective interventions

Idiopathic rapid eye movement (REM) sleep behaviour disorder (IRBD) manifests as unpleasant dreams and vigorous behaviours during REM sleep that can result in injuries. Patients with IRBD have no known neurological diseases or motor or cognitive complaints; however, this sleep disorder is not harmless. In most cases, IRBD is the prelude of the synucleinopathies Parkinson's disease, dementia with Lewy bodies, or, less frequently, multiple system atrophy. Patients can show abnormalities that are characteristic of the synucleinopathies, and longitudinal follow-up shows that most patients develop parkinsonism and cognitive impairments with time. Thus, diagnosis of IRBD needs to be accurate and involves informing the patient of the risk of developing a neurodegenerative disease. It is extraordinary for a sleep disorder to precede the full expression of a neurodegenerative disease, which renders IRBD of particular interest in studies of the prodromal stage of the synucleinopathies, and in the development of neuroprotective interventions to stop or slow neurodegenerative deterioration before motor and cognitive symptomatology emerges. Such therapeutics do not currently exist, and thus represent an unmet need in IRBD.

The Clinical Phenotype of Idiopathic Rapid Eye Movement Sleep Behavior Disorder at Presentation: A Study in 203 Consecutive Patients

OBJECTIVE

To describe the clinical phenotype of idiopathic rapid eye movement (REM) sleep behavior disorder (IRBD) at presentation in a sleep center.

METHODS

Clinical history review of 203 consecutive patients with IRBD identified between 1990 and 2014. IRBD was diagnosed by clinical history plus video-polysomnographic demonstration of REM sleep with increased electromyographic activity linked to abnormal behaviors.

RESULTS

Patients were 80% men with median age at IRBD diagnosis of 68 y (range, 50-85 y). In addition to the already known clinical picture of IRBD, other important features were apparent: 44% of the patients were not aware of their dream-enactment behaviors and 70% reported good sleep quality. In most of these cases bed partners were essential to convince patients to seek medical help. In 11% IRBD was elicited only after specific questioning when patients consulted for other reasons. Seven percent did not recall unpleasant dreams. Leaving the bed occurred occasionally in 24% of subjects in whom dementia with Lewy bodies often developed eventually. For the correct diagnosis of IRBD, video-polysomnography had to be repeated in 16% because of insufficient REM sleep or electromyographic artifacts from coexistent apneas. Some subjects with comorbid obstructive sleep apnea reported partial improvement of RBD symptoms following continuous positive airway pressure therapy. Lack of therapy with clonazepam resulted in an increased risk of sleep related injuries. Synucleinopathy was frequently diagnosed, even in patients with mild severity or uncommon IRBD presentations (e.g., patients who reported sleeping well, onset triggered by a life event, nocturnal ambulation) indicating that the development of a neurodegenerative disease is independent of the clinical presentation of IRBD.

CONCLUSIONS

We report the largest IRBD cohort observed in a single center to date and highlight frequent features that were not reported or not sufficiently emphasized in previous publications. Physicians should be aware of the full clinical expression of IRBD, a sleep disturbance that represents a neurodegenerative disease.

COMMENTARY

A commentary on this article appears in this issue on page 7.

Serum sex hormone levels in different severity of male adult obstructive sleep apnea-hypopnea syndrome in East Asians

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a serious health issue, which can impact the hormone secretion. The aim of this study is to analyze the relationship between serum sex hormone concentrations and different severity degree of OSAHS, and to evaluate the influence of OSAHS on sex hormone levels. We enrolled 116 subjects who were subjected to polysomnography (PSG). They were divided into three groups: control group (n=10) [apnea hypopnea index (AHI) <5/h], mild-moderate OSAHS group (n=15) (5≤AHI<30/h), and severe OSAHS group (n=91) (AHI≥30/h). The patients in OSAHS group were subdivided into obesity and non-obesity subgroups. The parameters such as AHI, body mass index (BMI), lowest oxygen saturation (LSaO2), and mean oxygen saturation (MSaO2) were recorded. Serum levels of testosterone, polactin, estradiol, follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined in the morning immediately after waking up. Mean levels of hormones were compared among groups. The correlation between hormone levels and sleep-breathing parameters was analyzed. No significant differences in serum sex hormone levels were found among control, mild-moderate OSAHS, and severe OSAHS groups (P>0.05). There was no correlation between AHI and sex hormone levels (P>0.05). Testosterone was significantly negatively correlated with BMI (P<0.05). These results suggested that BMI might have a direct effect on testosterone level, and it might be an important factor affecting testosterone level in male OSAHS patients, and there may be no correlation between severity of OSAHS and sex hormones levels.

Sleep Forensics: a critical review of the literature and brief comments on the Brazilian legal situation

Sleep medicine is a relatively new field among Medical Sciences. Its legal aspects are still obscure, either for lack of knowledge of the biological mechanisms underlying violent behaviour during sleep or the virtual absence of clear legal and uniformly accepted guidelines as to whether to punish or treat those disorders. An updated review of the pertinent literature was performed to determine the most prevalent pathological conditions involving violence and sleep and to identify their most common precipitating factors, attempting to provide some technical support to aid Brazilian medical-experts or assistants in preparing substantial and scientific-based reports in a legal environment.

Phasic muscle activity in sleep and clinical features of Parkinson disease

OBJECTIVE

The absence of atonia during rapid eye movement (REM) sleep and dream-enactment behavior (REM sleep behavior disorder [RBD]) are common features of sleep in the alpha-synucleinopathies. This study examined this phenomenon quantitatively, using the phasic electromyographic metric (PEM), in relation to clinical features of idiopathic Parkinson disease (PD). Based on previous studies suggesting that RBD may be prognostic for the development of later parkinsonism, we hypothesized that clinical indicators of disease severity and more rapid progression would be related to PEM.

METHODS

A cross-sectional convenience sample of 55 idiopathic PD patients from a movement disorders clinic in a tertiary care medical center underwent overnight polysomnography. PEM, the percentage of 2.5-second intervals containing phasic muscle activity, was quantified separately for REM and non-REM (NREM) sleep from 5 different electrode sites.

RESULTS

Higher PEM rates were seen in patients with symmetric disease, as well as in akinetic-rigid versus tremor-predominant patients. Men had higher PEM relative to women. Results occurred in all muscle groups in both REM and NREM sleep.

INTERPRETATION

Although our data were cross-sectional, phasic muscle activity during sleep suggests disinhibition of descending motor projections in PD broadly reflective of more advanced and/or progressive disease. Elevated PEM during sleep may represent a functional window into brainstem modulation of spinal cord activity and is broadly consistent with the early pathologic involvement of non-nigral brainstem regions in PD, as described by Braak.

REM sleep behaviour disorder in older individuals: epidemiology, pathophysiology and management

Rapid eye movement (REM) sleep behaviour disorder (RBD) is a sleep disorder in which patients appear to be enacting their dreams while in REM sleep. The behaviours are typically violent, in association with violent dream content, so serious harm can be done to the patient or the bed partner. The disorder predominantly affects older adults, and has an estimated prevalence in adults of 0.4-0.5%. However, the frequency is much higher in certain neurodegenerative diseases, especially Parkinson's disease, dementia with Lewy bodies and multiple systems atrophy. RBD can occur in the absence of diagnosed neurological diseases (the 'idiopathic' form), although patients with this form of RBD may have subtle neurological abnormalities and often ultimately develop a neurodegenerative disorder. Data from animal models and cases of RBD developing after brainstem (pontine tegmentum, medulla) lesions have led to the understanding that RBD is caused by a lack of normal REM muscle atonia and a lack of normal suppression of locomotor generators during REM sleep. Clonazepam is used as first-line therapy for RBD and melatonin as second-line therapy, although evidence for both of these interventions comes from uncontrolled case series. Because the risk of injury to the patient or the bed partner is high, interventions to improve the safety of the sleep environment are also often necessary. This review describes the epidemiology, pathophysiology and treatment of RBD.

Rapid eye movement sleep behavior disorder in women: relevance to general and specialty medical practice

Rapid eye movement (REM) sleep behavior disorder (RBD) is a treatable parasomnia involving dream-enacting behaviors that is considered to be a male-predominant disorder. However, it is speculated that underrecognition of RBD among female patients in part contributes to the male predominance, probably because women have less aggressive and violent RBD behaviors. We conducted a literature review focused primarily on women with RBD, in which the age of onset of RBD, types of nocturnal behaviors, presence of dream enactment, polysomnographic findings, clinical course, treatment response, male/female ratio, comorbid diagnoses, and medications were tabulated and discussed. RBD was found to primarily affect middle-aged and older women and those with a broad range of neurological disorders. As the link between RBD and neurodegenerative disorders, such as Parkinson's disease, becomes increasingly apparent, including the delayed emergence of parkinsonism in patients initially diagnosed with idiopathic RBD, primary care and specialty physicians should be aware of RBD in women, its potential complications, its excellent response to clonazepam, and its association with neurological disorders and older age groups.

The clinical and pathophysiological relevance of REM sleep behavior disorder in neurodegenerative diseases

REM sleep behavior disorder (RBD) is characterized by vigorous movements associated with unpleasant dreams and increased electromyographic activity during REM sleep. Polysomnography with audiovisual recording is needed to confirm the diagnosis of RBD and to exclude other sleep disorders that can mimic its symptoms including obstructive sleep apnea, nocturnal hallucinations and confusional awakenings. RBD may be idiopathic or related to neurodegenerative diseases, particularly multiple system atrophy, Parkinson's disease and dementia with Lewy bodies. RBD may be the first manifestation of these disorders, antedating the onset of parkinsonism, cerebellar syndrome, dysautonomia, and dementia by several years. RBD should thus be considered an integral part of the disease process. When effective, neuroprotective strategies should be considered in subjects with idiopathic RBD. Patients with other neurodegenerative diseases, though, such as spinocerebellar ataxias, may also present with RBD. When clinically required, clonazepam at bedtime is effective in decreasing the intensity of dream-enacting behaviors and unpleasant dreams in both the idiopathic and secondary forms. When part of a neurodegenerative disorder the development of RBD is thought to reflect the location and extent of the underlying lesions involving the REM sleep centers of the brain (e.g., locus subceruleus, amygdala, etc.), leading to a complex multiple neurotransmitter dysfunction that involves GABAergic, glutamatergic and monoaminergic systems. RBD is mediated neither by direct abnormal alpha-synuclein inclusions nor by striatonigral dopaminergic deficiency alone.