Antidepressants and REM sleep behavior disorder: isolated side effect or neurodegenerative signal?

REM sleep and neurodegeneration

Several brainstem, subcortical and cortical areas are involved in the generation of rapid eye movement (REM) sleep. The alteration of these structures as a result of a neurodegenerative process may therefore lead to REM sleep anomalies. REM sleep behaviour disorder is associated with nightmares, dream-enacting behaviours and increased electromyographic activity in REM sleep. Its isolated form is a harbinger of synucleinopathies such as Parkinson's disease or dementia with Lewy bodies, and neuroprotective interventions are advocated. This link might also be present in patients taking antidepressants, with post-traumatic stress disorder, or with a history of repeated traumatic head injury. REM sleep likely contributes to normal memory processes. Its alteration has also been proposed to be part of the neuropathological changes occurring in Alzheimer's disease.

Ictal SPECT Imaging Findings in Parkinson's Disease with Rapid Eye Movement Sleep Behavior Disorder

BACKGROUND

Rapid eye movement sleep behavior disorder (RBD) is an established prodrome and symptom of synucleinopathies. The pathophysiology of this disorder has been well studied but there is a lack of functional imaging data to illustrate the dysfunction in vivo.

OBJECTIVES

We aimed to investigate the functional changes of RBD, by performing ictal REM sleep SPECT, comparing subjects with Parkinson's Disease (PD) and evidence of RBD to subjects with PD and no RBD.

METHODS

Participants underwent a targeted clinical assessment, followed by video polysomnography (vPSG). Ictal 99mTc-HMPAO SPECT was performed by injecting the tracer during vPSG confirmed REM sleep in seven cases (PD with RBD) and five controls (PD without RBD). Voxel-wise, whole brain regional relative perfusion changes between both groups were assessed using statistical parametric mapping.

RESULTS

No difference in relative regional brain perfusion was demonstrated at a family wise error corrected p-value of 0.05 between the case and control groups. At an uncorrected P-value of <0.01, combined with a cluster extent threshold of 300 voxels, four clusters of increased perfusion were identified in the case group compared to the control group. The clusters were seen in the motor, somatosensory association, and prefrontal cortices. The reverse contrast did not show any significant clusters.

CONCLUSIONS

Increased perfusion of the motor cortex is in keeping with previous publications and motor phenomena seen in RBD. However, clusters included additional cortical regions. These findings demonstrate RBD as a wider sleep network dysfunction, rather than a manifestation of simple pontomedullary interruption.

Association of early-onset psychiatric disorders with REM sleep behavior disorder - A retrospective study

BACKGROUND

REM sleep behaviour disorder (RBD) is a known predictor of the subsequent development of neurodegenerative diseases, particularly Parkinson's disease and other alpha synucleinopathies. RBD has also been found to be common among children with other psychiatric disorders such as anxiety, depression, and ADHD.

OBJECTIVE

This retrospective study aims to analyze the prevalence of early-onset psychiatric disorders among patients referred for RBD to our sleep laboratory. Our hypothesis is that early-onset psychiatric disorders are more common in patients with polysomnographically confirmed RBD.

METHODS

A retrospective chart review was performed through the Kingston Health Sciences Centre (KHSC) Sleep Laboratory. Data collection involved gathering information regarding the patient's sleep study, psychiatric diagnoses and/or symptoms, mental health medication history and any neurodegenerative conditions noted in hospital clinical notes.

RESULTS

Patients referred for and polysomnographically confirmed RBD were more likely to have presented with symptoms, or received a clinical diagnosis, of an early-onset psychiatric disorder at 32 % compared to the obstructive sleep apnea (OSA) control group at 3 %.

CONCLUSIONS

History of early-onset psychiatric disorders is more common among patients referred as RBD compared to a control group of patients with OSA. Future studies are required to confirm the validity and replicability of this finding.

Loss of rapid eye movement atonia in rapid eye movement sleep behaviour disorder and narcolepsy

A reduction of physiological muscle atonia during rapid eye movement sleep is characteristic in patients with rapid eye movement sleep behaviour disorder, however, it can also be found in narcolepsy patients. We evaluated rapid eye movement sleep associated electromyographic activity to set cut-off values of rapid eye movement sleep without atonia, differentiating rapid eye movement sleep behaviour disorder and narcolepsy patients from controls to enable more precise future diagnostic criteria for these disorders. We retrospectively analysed polysomnography recordings of 16 rapid eye movement sleep behaviour disorder patients, 15 narcolepsy patients, and 19 controls. The combination of phasic and tonic electromyographic activity was recorded in the mentalis and tibialis anterior muscles and analysed in 3 second miniepochs. The cut-off value for a diagnosis of rapid eye movement sleep behaviour disorder was 17.07% (100% sensitivity, 94.7% specificity, area under the curve 0.997). For the diagnosis of narcolepsy, we yielded a cut-off value of 8.4% (86.4% sensitivity, 68.4% specificity, area under the curve 0.850). Rapid eye movement sleep without atonia significantly (p = 0.046) increased in the second night half in rapid eye movement sleep behaviour disorder patients, while it remained moderately increased in the narcolepsy group. Polysomnographic evaluation proves significantly higher rates of rapid eye movement sleep without atonia in rapid eye movement sleep behaviour disorder than in narcolepsy patients, allowing differentiation from controls with high sensitivity and specificity. An increase throughout the night is characteristic for rapid eye movement sleep behaviour disorder, whereas a consistent elevation is typical in narcolepsy patients.

REM Sleep Behavior Disorder Diagnostic Code Accuracy and Implications in the Real-World Setting

Background and Objectives

Isolated REM sleep behavior disorder (iRBD) carries increased risk of neurodegenerative parkinsonian disorder or dementia (NPD) but is difficult to accurately screen for in the community. Health care data offer the opportunity to identify large numbers of iRBD cases among outpatients. We aimed to determine the positive predictive value (PPV) of an RBD International Classification of Disorders (ICD) code for actual iRBD based on manual review of the electronic health record (EHR), examine risk of NPD diagnosis, and explore whether a statistical model developed using selected EHR data can identify individuals with the RBD ICD code who have high probability for actual iRBD.

Methods

In this retrospective cohort study, a search of the EHR at a single health care system was conducted to identify outpatients who received the ICD9 or ICD10 RBD code in 2011-2021. The EHR for each case was manually reviewed. Secondary RBD cases were excluded. Remaining cases were classified as no iRBD or actual iRBD (possible, probable, or definite). Incident cases of NPD were identified. PPV of presence of the RBD ICD code for actual iRBD was calculated. Cumulative incidence of NPD with death as a competing event was compared in those with vs without iRBD. Least absolute shrinkage and selection operator (LASSO) regression was used to build a prediction model for iRBD, and the model was validated in an independent data set.

Results

Among 1,130 cases with the RBD ICD code, 499 had secondary causes of RBD. For the remaining 628 cases, EHR review indicated no iRBD in 168 (26.8%). PPV of the RBD ICD code was 73.25%. Over a median follow-up of 4.7 years, compared with the no iRBD group, the iRBD group had a higher risk of NPD (subdistribution hazard ratio = 10.4 [95% CI 2.5-43.1]). The LASSO prediction model for iRBD had an area under the receiver operating characteristic curve of 0.844 (95% CI 0.806-0.880).

Discussion

PPV of an RBD ICD code is moderate. In the real-world setting, patients with iRBD had a high risk of incident diagnosis of NPD over 4.7 years. Results indicate feasibility of using statistical models developed using EHR data to accurately predict iRBD.

Factors associated with phenoconversion of idiopathic rapid eye movement sleep behavior disorder: a prospective study

This study explores the effect of risk factors on the progression of idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) to α-synucleinopathies in a Chinese cohort. Patients with iRBD were enrolled and assessed for environmental factors and lifestyle using standardized structured questionnaires at baseline. All patients were prospectively followed for phenoconversion monitoring. The cumulative incidence was estimated using survival analysis. Of 155 iRBD enrolled in the cohort, follow-up information was available in 141 patients. The phenoconversion rate was 16.3% after 3 years, 27.6% after 5 years, and 57.2% after 10 years. Eighteen participants converted within 3 years, 27 converted within 5 years, and 36 converted within 10 years. IRBD with positive family history of parkinsonism had an increased risk of being converted to α-synucleinopathies, while tea drinking was associated with a decreased phenoconversion risk. Our findings shed light on a potential application of tea drinking in modifying iRBD progression.

The causal relationship between type 2 diabetes mellitus and isolated REM sleep behavior disorder: results from multivariable and network Mendelian randomization analysis

Objectives

To investigate the causal relationship between type 2 diabetes mellitus (T2DM, exposure) and isolated REM sleep behavior disorder (iRBD, outcome).

Methods

Genome-wide association study (GWAS) data for iRBD comprised 9,447 samples, including 1,061 iRBD cases from the International RBD Study Group. Initially, we performed linkage disequilibrium score regression (LDSC) to explore the genetic correlation between T2DM and iRBD. Then the two-sample univariate MR (UVMR) analysis was conducted to examine the effects of T2DM and blood sugar metabolism-related factors on iRBD. Subsequently, we applied multivariable MR (MVMR) methods to further adjust for confounders. Lastly, we executed a network MR analysis, with cytokines and immune cell characteristics as potential mediators, aiming to investigate indirect effect of T2DM on iRBD.

Results

Results from LDSC suggest a genetic correlation between T2DM and iRBD (rg=0.306, P=0.029). UVMR analysis indicates that both T2DM (Odds Ratio [95% Confidence Interval] = 1.19 [1.03, 1.37], P = 0.017) and high blood glucose levels (1.55 [1.04, 2.30], P = 0.032) are risk factors for iRBD. Even after adjusting for confounders in MVMR, the association between T2DM and iRBD remains robust. Finally, results from network MR analysis suggest that T2DM may indirectly promote the development of iRBD by reducing levels of Stromal Cell-Derived Factor 2 in circulation and by increasing BAFF-receptor expression in IgD- CD38- B cells.

Conclusions

T2DM may promote the onset of iRBD by influencing immune-inflammatory responses. Our findings provide valuable insights and directions for understanding the pathogenesis of iRBD, identifying high-risk groups, and discovering new therapeutic targets.

Sleep disorder syndromes of post-acute sequelae of SARS-CoV-2 (PASC) / Long Covid

INTRODUCTION

COVID-19 infection has resulted in a high prevalence of a post-infectious syndrome, known as post-acute sequelae of SARS-CoV-2 (PASC) or "Long COVID". PASC is a heterogeneous disease with a high prevalence of sleep disturbances, varying from an insomnia disorder to excessive daytime sleepiness.

METHODS

Patients seen in the Covid Survivorship Program at the Beth Israel Deaconess Medical Center Boston, USA, were screened for sleep disorders as part of a comprehensive multi-system evaluation. Those who screened positive were referred for a comprehensive sleep evaluation in a dedicated COVID-19-Sleep clinic, followed by diagnostic sleep testing and treatment. This report summarizes patients who completed an American Academy of Sleep Medicine (AASM) accredited facility-based diagnostic evaluation. International Classification of Sleep Disorders 3rd Edition-Revised criteria were met for all diagnoses.

RESULTS

In 42 patients with PASC, five categories of sleep disorder syndromes were observed following a sleep clinic evaluation, including obstructive sleep apnea, chronic insomnia disorder, primary hypersomnia, REM behavior disorder (RBD), and new onset circadian phase delay. Seven patients met criteria for idiopathic hypersomnia, and two had narcolepsy type 2. RBD patients were infected in three different waves; circadian disturbance patients were all infected in the winter wave of 2020/21, and the primary hypersomnolence group occurred during all waves, predominantly the initial wave of 2020. A peculiar form of insomnia was a persistent loss of sleep regularity.

CONCLUSIONS

Specific sleep symptoms/syndromes are reported in this select group of patients with PASC/Long Covid. As new onset sleep complaints are prevalent in PASC, we recommend a complete clinical and investigative sleep evaluation for persistent severe sleep symptoms following COVID-19 infection.

Polysomnographic features prior to dream enactment behaviors in isolated rapid eye movement sleep behavior disorder

OBJECTIVE

This study aimed to identify electroencephalogram correlates of dream enactment behaviors (DEBs) and elucidate their cortical dynamics in patients with isolated/idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD).

METHODS

This cross-sectional study included 15 patients with iRBD. Two REM sleep periods in routine polysomnography were compared: the 60 s preceding the DEBs ("pre-representative behavior" [preR]), and the 60 s with the least submental electromyogram activity ("background" [BG]). Six EEG frequency bands and electrooculogram were analyzed; power spectra, coherence and phase-locking values in four 15-s periods were examined to assess trends. These indices were also compared between preR and BG.

RESULTS

Compared with BG, significantly higher delta power in the F3 channel and gamma power in the F4 and O2 channels were observed during preR. For functional connectivity, the widespread beta-band connectivity was significantly increased during preR than BG.

CONCLUSION

Before notable REM sleep behaviors, uneven distributed higher EEG spectral power in both very low and high frequencies, and increased wide-range beta band functional connectivity, were observed over 60 s, suggesting cortical correlates to subsequent DEBs.

SIGNIFICANCE

This study may shed light on the pathological mechanisms underlies RBD through the routine vPSG analysis, leading to detection of DEBs.

Prevalence and correlates of probable rapid eye movement sleep behavior disorder among middle-aged and older adults in a psychiatric outpatient clinic: A cross-sectional survey

OBJECTIVE

Rapid eye movement sleep behavior disorder (RBD) is often underdiagnosed among people living with mental disorders. The present study aimed to investigate the prevalence of probable RBD (pRBD) and its associated factors among middle-aged and older adults in a psychiatric outpatient clinic.

METHODS

We conducted a cross-sectional survey among 2907 people aged 45-80 years who visited the outpatient clinic between March 1 and August 31, 2022 in a psychiatric hospital. A cutoff score ≥5 on the RBD Screening Questionnaire (RBDSQ) was used to indicate the presence of probable RBD (pRBD). Potential factors associated with pRBD were also assessed with a structured checklist. The association between these factors and the presence of pRBD was examined with logistic regression.

RESULTS

The response rate was 64.3 %. Among 1868 respondents [age 58.5 ± 9.6 years, male n = 738 (39.5 %), female n = 1130 (60.5 %)], 15.9 % (95 % CI 14.2-17.6 %) screened positive for pRBD. Occupational exposure to chemicals; positive family history of psychotic disorders; a late start of mental health care; a medical history of autonomic dysfunction; mood problems; and use of antidepressants, hypnotics, and acetylcholinesterase inhibitors were associated with an increased likelihood of having pRBD (P < 0.05 for all).

CONCLUSION

pRBD is common among outpatients with mental disorders, especially in mental disorders due to neurological diseases and physical conditions, mood disorders and anxiety or somatoform disorders. The findings highlight the importance of identifying sleep behavior disorders among people living with mental disorders in clinical practice.

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.

Secondary RBD: Not just neurodegeneration

Rapid eye movement sleep behavior disorder is a parasomnia characterized by excessive muscle activity during rapid eye movement sleep (rapid eye movement sleep without atonia), along with dream enactment behavior. Isolated rapid eye movement sleep behavior disorder tends to occur in older males and is of concern due to the known link to Parkinson's disease and other synucleinopathies. When rapid eye movement sleep behavior disorder occurs in association with other neurological or general medical conditions, or resulting from the use of various substances, it is called secondary rapid eye movement sleep behavior disorder; the most common cause is neurodegenerative illness, specifically the synucleinopathies. Here, the focus will be on the subset of secondary rapid eye movement sleep behavior disorder in which there is no neurodegenerative disease.

Clinical presentations and diagnostic application of proposed biomarkers in psychiatric-onset prodromal dementia with Lewy bodies

Research criteria for the diagnosis of prodromal dementia with Lewy bodies (DLB) include three clinical subtypes: mild cognitive impairment with Lewy bodies (MCI-LB), delirium-onset prodromal DLB, and psychiatric-onset prodromal DLB. Late-onset psychiatric manifestations are at a higher risk of developing dementia, but its relation to prodromal DLB remains unclear. In addition to the risk of severe antipsychotic hypersensitivity reactions, accurate discrimination from non-DLB cases is important due to the potential differences in management and prognosis. This article aims to review a rapidly evolving psychiatric topic and outline clinical pictures of psychiatric-onset prodromal DLB, including the proposed biomarker findings of MCI-LB: polysomnography-confirmed rapid eye movement sleep behaviour disorder, cardiac [123I]metaiodobenzylguanidine scintigraphy, and striatal dopamine transporter imaging. We first reviewed clinical pictures of patients with autopsy-confirmed DLB. Regarding clinical reports, we focused on the patients who predominantly presented with psychiatric manifestations and subsequently developed DLB. Thereafter, we reviewed clinical studies regarding the diagnostic applications of the proposed biomarkers to patients with late-onset psychiatric disorders. Clinical presentations were mainly late-onset depression and psychosis; however, other clinical manifestations were also reported. Psychotropic medications before a DLB diagnosis may cause extrapyramidal signs, and potentially influences the proposed biomarker findings. These risks complicate clinical manifestation interpretation during the management of psychiatric symptoms. Longitudinal follow-up studies with standardised evaluations until conversion to DLB are needed to investigate the temporal trajectories of core features and proposed biomarker findings. In patients with late-onset psychiatric disorders, identification of patients with psychiatric-onset prodromal DLB provides the opportunity to better understanding the distinct prognostic subgroup that is at great risk of incident dementia. Advances in the establishment of direct biomarkers for the detection of pathological α-synuclein may encourage reorganising the phenotypic variability of prodromal DLB.

Biomarkers of neurodegeneration in isolated and antidepressant-related rapid eye movement sleep behavior disorder

BACKGROUND AND PURPOSE

This study compared the features of isolated rapid eye movement (REM) sleep behavior disorder (iRBD) and antidepressant-related REM sleep behaviour disorder (RBD) with the aim of highlighting markers that might distinguish the two entities.

METHODS

The observational cohort study included RBD patients with and without antidepressant use (antiD+ and antiD- patients, respectively), without cognitive impairment and parkinsonism. Clinical features of RBD, subtle motor and non-motor symptoms of parkinsonism, sleep architecture, REM atonia index, dopamine transporter-single photon emission computed tomography (DAT-SPECT) and skin biopsies for the intraneuronal alpha-synuclein (α-syn), were evaluated in the baseline work-up.

RESULTS

Thirty-nine patients, 10 antiD+ and 29 antiD-, were included. AntiD+ patients (more frequently female) reported more psychiatric symptoms, less violent dream enactment, and less frequent hyposmia. Dermal α-syn was detected in 93.1% of antiD- versus 30% of antiD+ patients (p = 0.00024). No differences appeared in other motor and non-motor symptoms, Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III score, DAT-SPECT, or polysomnographic features.

CONCLUSIONS

Patients with antidepressant-related RBD have clinical and neuropathological features suggesting a lower risk of evolution than those with iRBD.

Treatment of REM sleep behavior disorder with trazodone: report of 3 cases

Rapid eye movement sleep behavior disorder is a sleep disturbance characterized by the absence of regular paralysis during rapid eye movement sleep, accompanied by dream enactment behavior. The available pharmacotherapy options for treating rapid eye movement sleep behavior disorder are limited, and the utilization of antidepressants has yielded mixed results. We report 3 cases of isolated rapid eye movement sleep behavior disorder improved with trazodone. Doses of 50-100 mg of trazodone at bedtime over 4-6 months resulted in significant clinical improvement. These cases highlight that trazodone could serve as a treatment for isolated rapid eye movement sleep behavior disorder that does not respond to traditional treatments at submaximal dosages.

CITATION

Barrow J, Vendrame M. Treatment of REM sleep behavior disorder with trazodone: report of 3 cases. J Clin Sleep Med. 2024;20(5):821-823.

Rates and Predictors of Rapid Eye Movement Sleep Behavior Disorder Symptoms Among Post-9/11 Veterans

OBJECTIVE

Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI), which are prevalent conditions among post-9/11 veterans, increase risks of rapid eye movement (REM) sleep behavior disorder (RBD) and degenerative synucleinopathy. Rates and predictors of RBD symptoms were investigated by screening post-9/11 veterans for RBD with a validated questionnaire.

METHODS

In this cross-sectional analysis, consecutive patients in the Houston Translational Research Center for TBI and Stress Disorders (TRACTS) were screened with the English translation of the RBD Questionnaire-Hong Kong (RBDQ-HK). In addition to data from the standard TRACTS battery, systematic chart review was used to identify known sleep disorders mimicking or manifesting RBD.

RESULTS

Of the 119 patients with available RBDQ-HK scores, 71 (60%) and 65 (55%) screened positive for RBD, when a total score ≥21 and a factor 2 score ≥8 were used as cutoff scores, respectively. Univariable analyses with both cutoffs showed consistent associations between a positive RBDQ-HK screen and global sleep quality, number of TBI exposures, and PTSD severity. Multivariable logistic regression with total score ≥21 as a cutoff indicated that PTSD severity (odds ratio=1.06, 95% CI=1.02-1.10) and number of TBIs (odds ratio=1.63, 95% CI=1.16-2.41) were independent predictors of a positive screen, whereas global sleep quality was no longer significant. Multivariable logistic regression with factor 2 score ≥8 as a cutoff showed similar results.

CONCLUSIONS

Interdisciplinary parasomnia assessment, further validation of RBD screens, and standardized reporting of REM sleep without atonia could provide necessary information on the pathophysiological relationships linking PTSD, TBI, RBD symptoms, and ultimately synucleinopathy risk among post-9/11 veterans.

Resolving a paradox: antidepressants, neuroinflammation, and neurodegeneration

Depression is a known risk factor for dementia. Antidepressants are the most commonly used treatment for this condition, and are effective in at least half to two-thirds of cases. Extensive evidence from in vitro and animal models suggests that antidepressants have anti-inflammatory and neuroprotective properties. These effects have been shown to reduce the oxidative damage, amyloid aggregation, and expression of pro-inflammatory genes associated with animal models of neurodegenerative disorders. However, longitudinal research in humans has shown that antidepressants do not protect against dementia, and may even be associated with a risk of cognitive deterioration over time in older adults. The contrast between two sets of findings represents a paradox of significant clinical and public health significance, particularly when treating depression in late life. This review paper attempts to resolve this paradox by critically reviewing the medium- and long-term effects of antidepressants on peripheral immune-inflammatory responses, infection risk, gut microbiota, and neuroendocrine responses to stress, and how these effects may influence the risk of neurodegeneration. Briefly stated, it is possible that the peripheral actions of antidepressant medications may antagonize their beneficial effects against neuroinflammation. The implications of these findings are then explored with a particular focus on the development and testing of multimodal neuroprotective and anti-inflammatory treatments that could reduce the risk of Alzheimer’s and related dementias in patients suffering from depression.

Comparison of quantitative REM without atonia parameters in isolated REM sleep behavior disorder and early untreated Parkinson's disease

OBJECTIVES

To analyze REM sleep without atonia (RWA) metrics in patients with isolated REM sleep behavior disorder (iRBD), Parkinson's disease (PD) and healthy subjects and compare them in terms of degree of presumed brainstem damage.

METHODS

Forty-nine iRBD patients, 62 PD patients and 38 healthy controls were included into the analysis. Detailed polysomnographic and clinical data including motor, olfactory, autonomic, and cognitive assessment were obtained in all participants and subsequently compared within groups without RBD (i.e., healthy controls, PD-RBD-) and with RBD (i.e., iRBD, PD-RBD+). SINBAR criteria were used to score RWA.

RESULTS

Twenty-one PD patients (33.8 %) had RBD. When comparing PD-RBD-patients and controls, RWA tonic (p = 0.001) and RWA mixed (p = 0.03) were higher in PD-RBD-group. PD-RBD-patients had worse olfactory function than controls (p < 0.001); no significant difference in autonomic or cognitive function was registered. There were no significant differences in RWA parameters when comparing iRBD and PD-RBD + groups. iRBD patients had better olfactory function than PD-RBD+ (p = 0.006); no significant difference in autonomic or cognitive function was registered. PD-RBD + had worse autonomic (p = 0.006) and olfactory (p = 0.001) but not motor and cognitive function compared to PD-RBD-.

CONCLUSIONS

Untreated de-novo PD patients without RBD have increased RWA metrics compared to healthy subjects indicating subclinical degeneration of brainstem nuclei responsible for RWA. iRBD patients do not differ in RWA metrics from untreated de-novo PD patients with premotor RBD suggesting a similar level of brainstem degeneration caudal to substantia nigra in both groups. Groups with RBD are associated with autonomic dysfunction.

Medical, surgical, and physical treatments for Parkinson's disease

Although dopamine replacement therapy remains a core component of Parkinson's disease treatment, the onset of motor fluctuations and dyskinetic movements might require a range of medical and surgical approaches from a multidisciplinary team, and important new approaches in the delivery of dopamine replacement are becoming available. The more challenging, wide range of non-motor symptoms can also have a major impact on the quality of life of a patient with Parkinson's disease, and requires careful multidisciplinary management using evidence-based knowledge, as well as appropriately tailored strategies according to the individual patient's needs. Disease-modifying therapies are urgently needed to prevent the development of the most disabling refractory symptoms, including gait and balance difficulties, cognitive impairment and dementia, and speech and swallowing impairments. In the third paper in this Series, we present the latest evidence supporting the optimal treatment of Parkinson's disease, and describe an expert approach to many aspects of treatment choice where an evidence base is insufficient.

The clinical phenotype of psychiatric-onset prodromal dementia with Lewy bodies: a scoping review

BACKGROUND

Recent consensus research criteria have identified a 'psychiatric onset' form of prodromal dementia with Lewy bodies (DLB) characterised by prominent late-onset psychiatric symptoms. Although recognised as important to raise the index of diagnostic suspicion, evidence regarding this cohort was deemed too limited to impose formal criteria. We reviewed the published literature on psychiatric-onset DLB to identify key clinical characteristics and evidence gaps to progress our understanding of this entity.

METHODS

Medline, PubMed and Embase were searched for relevant articles containing longitudinal follow-up of patients initially presenting with a psychiatric illness who subsequently developed DLB according to the diagnostic criteria available at the time.

RESULTS

Two cohort studies (18 and 21 patients) along with 12 case series (13 cases) were identified totalling 52 patients (63% female). Initial psychiatric presentation occurred at a mean of 63 years (range 53-88), with depression being the most frequently reported psychiatric presentation (88%). Psychotic presentations were less common on presentation (11%) but became more prevalent throughout the prodromal period before the diagnosis of DLB (83%). Relapses of the psychiatric disease were common occurring in 94% (32/34) of patients. Parkinsonism, cognitive fluctuations, visual hallucinations, and REM sleep behaviour disorder were uncommonly reported at initial presentation (3.8%).

CONCLUSIONS

Psychiatric-onset DLB is characterized by a female predominant relapsing-remitting psychiatric illness presenting with affective symptoms but later developing psychotic features prior to the onset of DLB. Additional prospective studies including other neurodegenerative cohorts with harmonised assessments are required to inform definitive diagnostic criteria for this condition.

REM Behavior Disorder: Implications for PD Therapeutics

PURPOSE

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia that occurs during REM sleep, characterized by REM sleep without atonia (RSWA) and dream enactment behavior (DEB). RBD is associated with several diseases and medications but most notably is a prodromal feature of synucleinopathies, including Parkinson's disease (PD). This article reviews RBD, its treatments, and implications for PD therapeutics.

RECENT FINDINGS

Recent research recognizes RBD as a prodromal marker of PD, resulting in expansion of basic science and clinical investigations of RBD. Current basic science research investigates the pathophysiology of RBD and explores animal models to allow therapeutic development. Clinical research has focused on natural history observation, as well as potential RBD treatments and their impact on sleep and phenoconversion to neurodegenerative disease. RBD serves as a fresh access point to develop both neuroprotective and symptomatic therapies in PD. These types of investigations are novel and will benefit from the more established basic science infrastructure to develop new interventions.

Familial α-synucleinopathy spectrum features in patients with psychiatric REM sleep behaviour disorder

BACKGROUND

Rapid eye movement (REM) sleep behaviour disorder (RBD) is one of the earliest and most specific prodromes of the α-synucleinopathies including Parkinson's disease (PD). It remains uncertain whether RBD occurring in the context of psychiatric disorders (psy-RBD), although very common, is merely a benign epiphenomenon of antidepressant treatment, or whether it harbours an underlying α-synucleinopathy. We hypothesised that patients with psy-RBD demonstrate a familial predisposition to an α-synucleinopathy.

METHODS

In this case-control-family study, a combination of family history and family study method was used to measure the α-synucleinopathy spectrum features, which included RBD, neurodegenerative prodromal markers and clinical diagnoses of neurodegenerative disorders. We compared the risk of α-synucleinopathy spectrum features in the first-degree relatives (FDRs) of patients with psy-RBD, psychiatric controls and healthy controls.

RESULTS

There was an increase of α-synucleinopathy spectrum features in the psy-RBD-FDRs, including possible and provisional RBD (adjusted HR (aHR)=2.02 and 6.05, respectively), definite RBD (adjusted OR=11.53) and REM-related phasic electromyographic activities, prodromal markers including depression (aHR=4.74) and probable subtle parkinsonism, risk of prodromal PD and clinical diagnosis of PD/dementia (aHR=5.50), as compared with healthy-control-FDRs. When compared with psychiatric-control-FDRs, psy-RBD-FDRs consistently presented with a higher risk for the diagnosis and electromyographic features of RBD, diagnosis of PD/dementia (aHR=3.91) and risk of prodromal PD. In contrast, psychiatric controls only presented with a familial aggregation of depression.

CONCLUSION

Patients with psy-RBD are familially predisposed to α-synucleinopathy. The occurrence of RBD with major depression may signify a subtype of major depressive disorders with underlying α-synucleinopathy neurodegeneration.

TRIAL REGISTRATION NUMBER

NCT03595475.

Quantitative Network Comparisons of REM Sleep Without Atonia Across the α-Synucleinopathy Spectrum: A Systematic Review

Purpose

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is characterized by REM sleep without atonia (RWA) and is regarded as the prodromal stage of α-synucleinopathies, such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). RWA is also associated with neurodegeneration driven by α-synucleinopathy. However, the level of RWA across the α-synucleinopathy spectrum remains elusive. We aimed to rate the percentage of RWA across the α-synucleinopathy spectrum, encompassing prodromal and overt phenotypes.

Methods

A systematic search was conducted in the PubMed, Embase, Web of Science, and Cochrane Library databases. We included cohort, cross-sectional, and case-control studies comparing the RWA percentage during REM sleep evaluated by tonic chin activity (RWA%-T) or by phasic chin activity (RWA%-P) across the α-synucleinopathy spectrum. Bayesian network meta-analysis was used to combine both direct and indirect evidence regarding the group differences in the RWA%-T and RWA%-P. The surface under the cumulative ranking curve was used to estimate the ranked probability.

Results

Fifteen articles met the inclusion criteria. The investigations included 204 iRBD, 295 PD with RBD (PDwtRBD), 187 PD without RBD (PDwoRBD), 42 MSAwtRBD, 9 DLBwtRBD patients, and 246 controls. MSAwtRBD ranked first in RWA%-T, whereas iRBD ranked first in RWA%-P. RWA% in PDwoRBD patients was comparable to that in the controls and was lower than that in PDwtRBD patients.

Conclusion

Overt phenotypes such as MSAwtRBD and PDwtRBD ranked high in RWA%-T, whereas iRBD, a prodromal type, ranked highest in RWA%-P. Taken together, our data suggest that the percentage of neurodegeneration in RBD patients may be associated with RWA%-T rather than RWA%-P.

Prospero Registration Number

CRD42021276445.

Parkinson's Disease: A Narrative Review on Potential Molecular Mechanisms of Sleep Disturbances, REM Behavior Disorder, and Melatonin

Parkinson's disease (PD) is one of the most common neurodegenerative diseases. There is a wide range of sleep disturbances in patients with PD, such as insomnia and rapid eye movement (REM) sleep behavior disorder (or REM behavior disorder (RBD)). RBD is a sleep disorder in which a patient acts out his/her dreams and includes abnormal behaviors during the REM phase of sleep. On the other hand, melatonin is the principal hormone that is secreted by the pineal gland and significantly modulates the circadian clock and mood state. Furthermore, melatonin has a wide range of regulatory effects and is a safe treatment for sleep disturbances such as RBD in PD. However, the molecular mechanisms of melatonin involved in the treatment or control of RBD are unknown. In this study, we reviewed the pathophysiology of PD and sleep disturbances, including RBD. We also discussed the potential molecular mechanisms of melatonin involved in its therapeutic effect. It was concluded that disruption of crucial neurotransmitter systems that mediate sleep, including norepinephrine, serotonin, dopamine, and GABA, and important neurotransmitter systems that mediate the REM phase, including acetylcholine, serotonin, and norepinephrine, are significantly involved in the induction of sleep disturbances, including RBD in PD. It was also concluded that accumulation of α-synuclein in sleep-related brain regions can disrupt sleep processes and the circadian rhythm. We suggested that new treatment strategies for sleep disturbances in PD may focus on the modulation of α-synuclein aggregation or expression.

Management of REM sleep behavior disorder: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment

This systematic review provides supporting evidence for a clinical practice guideline for the management of rapid eye movement (REM) sleep behavior disorder in adults and children. The American Academy of Sleep Medicine commissioned a task force of 7 experts in sleep medicine. A systematic review was conducted to identify randomized controlled trials and observational studies that addressed interventions for the management of REM sleep behavior disorder in adults and children. Statistical analyses were performed to determine the clinical significance of critical and important outcomes. Finally, the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) process was used to assess the evidence for making recommendations. The literature search identified 4,690 studies; 148 studies provided data suitable for statistical analyses; evidence for 45 interventions is presented. The task force provided a detailed summary of the evidence assessing the certainty of evidence, the balance of benefits and harms, patient values and preferences, and resource use considerations.

CITATION

Howell M, Avidan AY, Foldvary-Schaefer N, et al. Management of REM sleep behavior disorder: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment. J Clin Sleep Med. 2023;19(4):769-810.

The Influence of GBA and LRRK2 on Mood Disorders in Parkinson's Disease

Background

Mood disorders have emerged as major non-motor comorbidities in Parkinson's disease (PD) even at the prodromal stage of the disease. Mutations in the LRRK2 and GBA genes are common among Ashkenazi Jews, with more severe phenotype reported for GBA-PD.

Objective

To explore the association between genetic status and mood related disorders before and after diagnosis of PD and the association between mood-related medications, phenotype, and genetic status.

Methods

Participants were genotyped for mutations in the LRRK2 and GBA genes. State of depression, anxiety and non-motor features were evaluated using validated questionnaires. History of mood disorders prior to diagnosis of PD and use of mood-related medications were assessed.

Results

The study included 105 idiopathic PD (iPD), 55 LRRK2-PD and 94 GBA-PD. Scores on mood related questionnaires and frequency of depression and anxiety before diagnosis were similar between the groups (p>0.05). However, more GBA-PD patients used mood related medications before PD diagnosis than LRRK2-PD and iPD (16.5% vs 7.1% and 8.2%, p=0.044). LRRK2-PD and GBA-PD receiving mood-related medications at time of assessment had worse motor and non-motor phenotype compared to those that did not (p<0.05). LRRK2-PD receiving mood related-medications at time of assessment, scored higher on mood-related questionnaires compared to LRRK2-PD not receiving such medications (p<0.04).

Conclusions

Prodromal GBA-PD are more frequently treated with mood related-medications despite equal rates of reported mood-related disorders, while LRRK2-PD with mood-related disorders experience high rates of anxiety and depression despite treatment, attesting to the need of more precise assessment and treatment of these genetic subgroups.

Louis EK, Forsberg LK, Fields JA, Huddleston DE, Bliwise DL, Avidan AY, Howell MJ, Schenck CH, McLeland J, Criswell SR, Videnovic A, During EH, Miglis MG, Shprecher DR, Lee‐Iannotti JK, Boeve BF, Ju YS. Baseline characteristics of the North American prodromal Synucleinopathy cohort

OBJECTIVE

Rapid eye movement (REM) sleep behavior disorder (RBD) is widely considered a prodromal synucleinopathy, as most with RBD develop overt synucleinopathy within ~10 years. Accordingly, RBD offers an opportunity to test potential treatments at the earliest stages of synucleinopathy. The North American Prodromal Synucleinopathy (NAPS) Consortium has created a multisite RBD participant, primarily clinic-based cohort to better understand characteristics at diagnosis, and in future work, identify predictors of phenoconversion, develop synucleinopathy biomarkers, and enable early stage clinical trial enrollment.

METHODS

Participants ≥18 years of age with overnight polysomnogram-confirmed RBD without Parkinson's disease, dementia, multiple system atrophy, or narcolepsy were enrolled from nine sites across North America (8/2018 to 4/2021). Data collection included family/personal history of RBD and standardized assessments of cognitive, motor, sensory, and autonomic function.

RESULTS

Outcomes are primarily reported based on sex (361 total: n = 295 male, n = 66 female), and secondarily based on history of antidepressant use (n = 200 with, n = 154 without; with correction for sex differences) and based on extent of synucleinopathy burden (n = 56 defined as isolated RBD, n = 305 defined as RBD+ [i.e., exhibiting ≥1 abnormality]). Overall, these participants commonly demonstrated abnormalities in global cognition (MoCA; 38%), motor function (alternate tap test; 48%), sensory (BSIT; 57%), autonomic function (orthostatic hypotension, 38.8%), and anxiety/depression (BAI and PHQ-9; 39.3% and 31%, respectively).

INTERPRETATION

These RBD participants, assessed with extensive history, demographic, cognitive, motor, sensory, and autonomic function demonstrated a lack of sex differences and high frequency of concomitant neurological abnormalities. These participants will be valuable for future longitudinal study and neuroprotective clinical trials.

Ethical Aspects of Prodromal Synucleinopathy Prognostic Counseling

Alpha-synucleinopathies can be identified in their prodromal phase, raising several ethical issues. In this review, we first provide definitions of prodromal α-synucleinopathies and discuss the importance of distinguishing between prodromes and risk factors. Next, we discuss the implications of a diagnosis of prodromal α-synucleinopathy and considerations regarding prognostic counseling in both clinical and research settings. We review available data on patient preferences regarding disclosure as well as providers' perspectives. We examine the pros and cons of disclosing a diagnosis of prodromal α-synucleinopathy, taking into consideration the differences between clinical and research settings. Asking about willingness to know in clinical and research settings and the shared decision-making process applied to prognostic counseling is discussed. Concerning research settings, ethical aspects regarding clinical trials are addressed. Availability of direct-to-consumer technologies will likely lead to novel contexts requiring prognostic counseling, and future neuroprotective or neuromodulating treatments may require further considerations on the timing, role, and importance of prognostic counseling. Recommendations on how to address ethical gaps should be a priority for patients, medical professional societies, and research workgroups. Ethical issues must be considered as an integral part of the overall clinical and research approach to prodromal synucleinopathies.

Quantification of REM sleep without atonia: A review of study methods and meta-analysis of their performance for the diagnosis of RBD

The present review focuses on REM sleep without atonia (RSWA) scoring methods. In consideration of the numerous papers published in the last decade, that used different methods for the quantification of RSWA, their systematic revision is an emerging need. We made a search using the PubMed, Embase, Scopus and Web of Science Databases, from 2010 until December 2021, combining the search term "RSWA" with "scoring methods", "IRBD", "alfasyn disease", and "neurodegenerative disease", and with each of the specific sleep disorders, diagnosed according to current criteria, with the identification of the references of interest for the topic. Furthermore, a Meta-analysis of the diagnostic performance of RSWA scoring methods, in terms of sensitivity and specificity, was carried out. The comparison of the hierarchical summary receiver-operating characteristic curves obtained for visual methods and that obtained for the automated REM sleep atonia index (RAI), shows substantially similar prediction areas indicating a comparable performance. This systematic review and meta-analysis support the validity of a series of visual methods and of the automated RAI in the quantification of RSWA with the purpose to guide clinicians in the interpretation of their results and their correct and efficient use within the diagnostic work-up for REM sleep behavior disorder.

Effects of bupropion and SSRI antidepressants on leg movement activity and chin muscle tone during sleep in adolescents

STUDY OBJECTIVES

To evaluate the effects of bupropion on periodic limb movements during sleep (PLMS) and chin electromyography tone in children taking it for their mood disorder, compared to the effects of selective serotonin reuptake inhibitors (SSRIs) and of bupropion combined with SSRIs.

METHODS

Six adolescents (aged 16.0 ± 0.63 years) taking bupropion alone and 6 adolescents (aged 15.9 ± 1.36 years) taking bupropion in combination with an SSRI antidepressant were recruited, along with 10 adolescents (aged 16.2 ± 0.2 years) taking different SSRIs, and they were also enrolled together with 17 age- and sex-matched control patients (aged 15.5 ± 1.26 years). Polysomnographic studies were obtained, and participants' leg movement activity during sleep and muscle tone were assessed quantitatively (atonia index) during all sleep stages.

RESULTS

Participants taking SSRIs showed PLMS indices significantly higher than those of control patients, whereas adolescents taking bupropion showed only slightly increased indexes of nonperiodic leg movements during sleep. No differences in PLMS were observed between adolescents taking bupropion alone or in association with SSRIs. The atonia index showed, within each sleep stage, the lowest values in the 2 groups taking SSRIs and the highest in the control patients; adolescents taking bupropion alone tended to show values slightly smaller than those of the control patients.

CONCLUSIONS

We found that similar to adults, in adolescents SSRIs but not bupropion are associated with increased PLMS. Bupropion also seems to counteract the SSRI-induced increase of PLMS, when administered in combination; thus, the dopaminergic effect of bupropion seems to outmatch the antidopaminergic action of SSRIs. Conversely, bupropion does not counteract the effects of SSRIs on chin electromyography tone.

CITATION

DelRosso LM, Mogavero MP, Fickensher A, Bruni O, Schenck CH, Ferri R. Effects of bupropion and SSRI antidepressants on leg movement activity and chin muscle tone during sleep in adolescents. J Clin Sleep Med. 2023;19(1):151-161.

Towards an understanding of the pathological basis of senile depression and incident dementia: Implications for treatment

Senile depression (SD) is a heterogeneous syndrome. Several clinical profiles are more likely to appear in SD than in early-life depression, but it remains unclear whether the pathophysiology is different. The prevalence of dementia increases with aging, and the underlying pathophysiological processes in the preclinical phase begin even before cognitive deficits or neurological signs appear. SD may be either a risk factor for developing dementia or a prodromal stage of dementia. The inconsistent findings regarding the association between SD and incident dementia may be attributable to the neuropathological heterogeneity underlying SD. Most studies have focused on patients with the clinical diagnosis of Alzheimer disease (AD) as an outcome, but several clinicopathological studies suggest that primary age-related tauopathy and argyrophilic grain disease may account for a proportion of cases clinically misdiagnosed as AD in the elderly population. Furthermore, most AD cases have additional neuropathologic changes such as cerebrovascular disease and Lewy body disease. Here, we review the neuropathological findings linking SD to incident dementia, focusing on common age-related neuropathologies. In particular, the roles of disturbance of neural circuity, imbalance of monoaminergic systems, dysregulation of the hypothalamic-pituitary-adrenal axis, and elevated neuroinflammatory status are discussed. Finally, we review the current treatment of SD in the context of age-related neuropathological changes.

Tonic REM sleep muscle activity is the strongest predictor of phenoconversion risk to neurodegenerative disease in isolated REM sleep behaviour disorder

Previous studies have shown that rapid eye movement sleep without atonia during polysomnography can predict the risk of phenoconversion to neurodegenerative disease in patients with isolated rapid eye movement sleep behaviour disorder. Discrepancy remains with regards to the morphology of rapid eye movement sleep without atonia that best predicts phenoconversion risk. This study aimed to ascertain the predictive value of tonic, phasic and mixed rapid eye movement sleep without atonia in patients with isolated rapid eye movement sleep behaviour disorder, at time of diagnosis. Sixty-four patients with polysomnography-confirmed isolated rapid eye movement sleep behaviour disorder, including 19 who phenoconverted during follow-up, were identified from an existing database. Tonic, phasic, mixed and "any" rapid eye movement sleep without atonia activity from the mentalis, tibialis anterior and flexor digitorum superficialis muscles was analysed blind to status using the diagnostic polysomnography. Rapid eye movement sleep without atonia variables were compared between converters and non-converters. Rapid eye movement sleep without atonia cut-offs predicting phenoconversion were established using receiver-operating characteristic analysis. The mean follow-up duration was 5.50 ± 4.73 years. Phenoconverters (n = 19) had significantly higher amounts of tonic (22.2 ± 19.1%, p = 0.0014), mixed (18.1 ± 14.1%, p = 0.0074) and "any" (mentalis muscle; 58.7 ± 28.0%, p = 0.0009) and all muscles (68.0 ± 20.8%, p = 0.0049) rapid eye movement sleep without atonia at diagnosis than non-converters. Optimal rapid eye movement sleep without atonia cut-off values predicting phenoconversion were 5.8% for tonic (73.7% sensitivity; 75.6% specificity), 7.3% for mixed (68.4% sensitivity; 73.3% specificity) and 43.6% for "any" (mentalis muscle; 68.4% sensitivity; 80.0% specificity) activity. "Any" (mentalis muscle) rapid eye movement sleep without atonia had the highest area under the curve (0.809) followed by tonic (0.799). The percentage of tonic rapid eye movement sleep without atonia was the strongest biomarker of phenoconversion in this cohort of patients with isolated rapid eye movement sleep behaviour disorder.

Drugs Used in Parasomnia

Parasomnias, especially disorders of arousal during childhood, are often relatively benign and transitory and do not usually require a pharmacologic therapy. A relevant aspect in both nonrapid eye movement and rapid eye movement parasomnia treatment is to prevent sleep-related injuries by maintaining a safe environment. Physicians should always evaluate the possible presence of favoring and precipitating factors (sleep disorders and drugs). A pharmacologic treatment may be indicated in case of frequent, troublesome, or particularly dangerous events. The aim of this article is to review current available evidence on pharmacologic treatment of different forms of parasomnia.

What respiratory physicians should know about parasomnias

Parasomnias have significant quality-of-life, prognostic and potentially forensic implications for patients and their bed-partners. Identifying key clinical features will accelerate diagnosis and appropriate management for these patients. Parasomnias are undesirable physical events or experiences that arise out of, or during, sleep. They can include movements, behaviours, emotions, perceptions, dreams or autonomic nervous system activity. While more common during childhood, they can persist into, or present de novo, during adulthood. Parasomnias can arise out of non-rapid eye movement (NREM) sleep, as in confusional arousals, sleepwalking, sleep terrors or sleep-related eating disorder, or out of REM sleep, as in REM behaviour disorder, recurrent isolated sleep paralysis or nightmare disorder. Sleep-related hypermotor epilepsy is an important differential diagnosis to consider in patients presenting with a parasomnia. A thorough clinical history, including a collateral history if available, is crucial to identify characteristic clinical features. Video polysomnography is useful to identify macro- and micro-sleep architectural features, characteristic behavioural events, and any concomitant sleep pathologies. Treatment of parasomnias involves a combined approach of pharmacological and non-pharmacological intervention, including safety measures, sleep hygiene and medicines such as clonazepam or melatonin to improve sleep consolidation and reduce behavioural activity. As parasomnias can not only be disruptive for the patient and their bed-partner but have important prognostic or forensic consequences, an understanding of their pathophysiology, clinical features and management is valuable for any respiratory physician who may encounter them.

Educational aims

To understand the common features of NREM and REM parasomnias.To differentiate between the causes of motor behaviours during sleep.To discuss the treatment approach for NREM and REM parasomnias.

REM sleep behavior disorder as a complex condition with heterogeneous underlying disorders: clinical management and prognostic implications [Commentary]

PURPOSE

To review how REM sleep behavior disorder (RBD) is a complex condition with heterogeneous underlying disorders; and to review clinical management issues and prognostic implications.

METHODS

PubMed literature search and contents from the first textbook of RBD (2018).

RESULTS

RBD, with its core objective diagnostic feature of REM-without-atonia (RWA) documented by video-polysomnography, can emerge during the entire lifespan, and can initially present as an idiopathic (isolated) condition (iRBD), or can be associated with a broad spectrum of disorders including narcolepsy, alpha-synuclein neurodegenerative disorders (esp. Parkinson's disease [PD] and dementia with Lewy bodies [DLB]), paraneoplastic neurological syndromes and autoimmune disorders, CNS lesions (e.g., tumors, stroke), other neurological disorders, psychiatric disorders (PTSD, mood disorders), can be triggered by antidepressant/other medications, and can emerge acutely with drug withdrawal states, toxic-metabolic states, etc. Important clinical issues include the evolution of iRBD to PD/DLB in most middle-aged and older patients over a period of years to several decades, with compelling prognostic implications, along with the hope of enrolling these patients in future clinical trials to test promising disease-modifying therapies. Also, the strong link of RBD with narcolepsy needs further investigation. Parasomnia overlap disorder involves RBD and NREM parasomnias that can be idiopathic or linked with a broad range of clinical disorders. RBD usually responds to therapy consisting mainly of melatonin and/or clonazepam at bedtime. The complex associations of RBD with OSA are being increasingly investigated. RBD mimics with dream-enactment need to be recognized for diagnostic and management purposes, including severe OSA, NREM parasomnias, PLMD, nocturnal seizures, and other conditions.

CONCLUSIONS

The clinical and research RBD fields span across the disciplines of neurology, pulmonary, psychiatry, psychology, and pediatric sleep medicine, along with physical medicine and rehabilitation medicine, other allied disciplines, and the basic and clinical neurosciences.

Evolution of Prodromal REM Sleep Behavior Disorder to Neurodegeneration: A Retrospective, Longitudinal Case-control Study

BACKGROUND AND OBJECTIVES

Individuals with a history of recurrent dream-enactment behaviors, but with subthreshold REM sleep without atonia levels for REM sleep behavior disorder (RBD) diagnosis, are currently classified to have prodromal RBD (pRBD). However, the REM sleep elevated EMG diagnostic cut-off, progression trajectory, and long-term neurodegenerative outcome of pRBD are not well understood. This study aimed to delineate the evolution of REM sleep EMG levels, determine the EMG cut-off score for diagnosing pRBD, and examine the risk for neurodegenerative diseases of pRBD.

METHODS

This retrospective longitudinal case-control study recruited pRBD patients and age, sex, and follow-up duration matched controls who were free of neurodegenerative disease at baseline in the Sleep Assessment Unit, the Chinese University of Hong Kong from 1997 to 2018. Patients and controls underwent clinical and video-polysomnography assessments at baseline and follow-up(s). REM sleep EMG activity level on mentalis and anterior tibialis (AT) muscles on video-polysomnography at each visit was scored. The diagnosis of neurodegenerative diseases was confirmed by a neurologist.

RESULTS

44 patients (67.4 ± 8.2 years old, 6 females) and 44 controls were recruited. The combined REM sleep EMG level on mentalis and AT muscles of pRBD patients significantly increased during 8.2 ± 3.3 years of follow-up (from 19.3 ± 9.7% to 47.3 ± 27.4% with estimated annual increase of 3.9%), yielding 29 pRBD patients (66%) meeting the full-blown RBD diagnostic criteria. Baseline REM sleep mentalis and AT muscles EMG activity of patients who developed full-blown RBD could favourably differentiate pRBD from controls (6.3% for mentalis 'any' and 9.1% for combination of mentalis 'any' and bilateral AT muscles phasic EMG with AUC of 0.88 [0.78-0.98] and 0.97 [0.92-1.00] respectively). pRBD patients had a higher risk for neurodegenerative diseases (9 developed Parkinson's disease and 3 developed dementia with Lewy bodies) when compared to controls (5 developed Alzheimer's disease, adjusted hazard ratio = 2.95, 95% CI = 1.02-8.54).

CONCLUSIONS

pRBD has a predictive progression in both pathophysiology and neurodegenerative outcome. This finding has significant implications to the nosological status of pRBD, the current REM sleep-related EMG diagnostic criteria, spectrum concept of RBD and future neuroprotective intervention.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that EMG activity during REM sleep predicts the development of prodromal REM sleep behavior disorder.

Dream Enactment Behaviors Associated With Posttraumatic Stress Disorder

The investigators aimed to draw attention to current debates surrounding the etiologies of dream enactment behaviors in patients with posttraumatic stress disorder (PTSD). The phenomenological overlap between PTSD-related nocturnal symptoms, rapid eye movement sleep behavior disorder (RBD), and trauma-associated sleep disorder (TASD) is discussed. Strategies used to diagnose and manage dream enactment behaviors, whether due to RBD or another confounding sleep disorder, are considered. Finally, the need for further research on the pathophysiological overlap and integrated treatment of PTSD, RBD, and, possibly, TASD is highlighted.

Louis EK. Objective sleep profile in LGI1/CASPR2 autoimmunity

STUDY OBJECTIVES

Rapid eye movement (REM) sleep behavior disorder (RBD) and other sleep disturbances are frequent in leucine-rich, glioma inactivated protein 1-IgG (LGI1) and contactin-associated protein 2-IgG (CASPR2) autoimmunity, yet polysomnographic analyses of these disorders remain limited. We aimed to characterize clinical presentations and analyze polysomnographic manifestations, especially quantitative REM sleep without atonia (RSWA) in LGI1/CASPR2-IgG seropositive (LGI/CASPR2+) patients.

METHODS

We retrospectively analyzed clinical and polysomnographic features and quantitative RSWA between LGI1+/CASPR2+ patients and age-sex matched controls. Groups were compared with Wilcoxon rank-sum and chi-square tests. Combined submentalis and anterior tibialis (SM + AT) RSWA was the primary outcome.

RESULTS

Among 11 (LGI1+, n = 9; CASPR2+, n = 2) patients, Morvan syndrome sleep features were present in seven (63.6%) LGI1+/CASPR2+ patients, with simultaneous insomnia and dream enactment behavior (DEB) in three (27.3%), and the most common presenting sleep disturbances were DEB (n = 5), insomnia (n = 5), and sleep apnea (n = 8; median apnea-hypopnea index = 15/hour). Median Epworth Sleepiness Scale was nine (range 3-24; n = 10), with hypersomnia in four (36.4%). LGI1+/CASPR2+ patients had increased N1 sleep (p = .02), decreased REM sleep (p = .001), and higher levels of SM + AT any RSWA (p < .001). Eight of nine (89%) LGI1+ exceeded RBD RSWA thresholds (DEB, n = 5; isolated RSWA, n = 3). RSWA was greater in AT than SM. All 10 LGI1+/CASPR2+ patients treated with immunotherapy benefitted, and 5/10 had improved sleep disturbances.

CONCLUSIONS

LGI1/CASPR2-IgG autoimmunity is associated with prominent dream enactment, insomnia, RSWA, sleep apnea, and shallower sleep. Polysomnography provides objective disease markers in LGI1+/CASPR2+ autoimmunity and immunotherapy may benefit associated sleep disturbances.

Parasomnias in patients with addictions-a systematic review

Parasomnias are involuntary behaviors or subjective experiences during sleep. Our objective was to review existing information on the presence of parasomnias in patients with addictions or during treatment for addictions. Information about parasomnias related to rapid-eye-movement (REM) and non-REM sleep in patients with addictions, while using substances or in abstinence, was reviewed. A systematic search of published articles reporting parasomnias as a consequence of drug use or abuse was conducted in the PubMed and SciELO databases. The search for the studies was performed in three phases: (1) by title, (2) by abstract, and (3) by complete text. The search was performed independently by two researchers, who then compared their results from each screening phase. Seventeen articles were found. The consumption of alcohol was reported in association with arousal disorders, such as sexsomnia and sleep-related eating disorder; and REM sleep behavior disorder was reported during alcohol withdrawal. Cocaine abuse was associated with REM sleep behavior disorder with drug consumption dream content. Overall, we found that several types of parasomnias were very frequent in patients with addictions. To avoid accidents in bedroom, legal problems, and improve evolution and prognosis; must be mandatory to include security measures related to sleep period; avoid pharmacological therapy described as potential trigger factor; improve sleep hygiene; and give pharmacological and behavioral treatments for patients with these comorbid sleep disorders.

Clinical and imaging evidence of brain-first and body-first Parkinson's disease

Braak's hypothesis has been extremely influential over the last two decades. However, neuropathological and clinical evidence suggest that the model does not conform to all patients with Parkinson's disease (PD). To resolve this controversy, a new model was recently proposed; in brain-first PD, the initial α-synuclein pathology arise inside the central nervous system, likely rostral to the substantia nigra pars compacta, and spread via interconnected structures - eventually affecting the autonomic nervous system; in body-first PD, the initial pathological α-synuclein originates in the enteric nervous system with subsequent caudo-rostral propagation to the autonomic and central nervous system. By using REM-sleep behavior disorder (RBD) as a clinical identifier to distinguish between body-first PD (RBD-positive at motor symptom onset) and brain-first PD (RBD-negative at motor symptom onset), we explored the literature to evaluate clinical and imaging differences between these proposed subtypes. Body-first PD patients display: 1) a larger burden of autonomic symptoms - in particular orthostatic hypotension and constipation, 2) more frequent pathological α-synuclein in peripheral tissues, 3) more brainstem and autonomic nervous system involvement in imaging studies, 4) more symmetric striatal dopaminergic loss and motor symptoms, and 5) slightly more olfactory dysfunction. In contrast, only minor cortical metabolic alterations emerge before motor symptoms in body-first. Brain-first PD is characterized by the opposite clinical and imaging patterns. Patients with pathological LRRK2 genetic variants mostly resemble a brain-first PD profile whereas patients with GBA variants typically conform to a body-first profile. SNCA-variant carriers are equally distributed between both subtypes. Overall, the literature indicates that body-first and brain-first PD might be two distinguishable entities on some clinical and imaging markers.

Progressive Olfactory Impairment and Cardiac Sympathetic Denervation in REM Sleep Behavior Disorder

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (iRBD) is prodromal for Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

OBJECTIVE

We investigated the use of cardiac [123I]meta-iodo-benzyl-guanidine scintigraphy ([123I]MIBG) and olfactory testing- in comparison to [123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single photon emission computed tomography ([123I]FP-CIT-SPECT)- for identifying iRBD patients as prodromal phenotype of PD/DLB.

METHODS

37 RBD subjects underwent cardiac [123I]MIBG and brain [123I]FP-CIT-SPECT at baseline. Olfactory (Sniffin' Sticks), cognitive and motor functions were tested annually for ∼4 years.

RESULTS

29/37 (78.4%) subjects had a pathological [123I]MIBG, of whom 86.2% (25/29) presented at least a moderate hyposmia at baseline (threshold/discrimination/identification-(TDI-)score ≤25). 20/37 (54.1%) subjects had a pathological [123I]FP-CIT-SPECT, always combined with a pathological [123I]MIBG. In subjects with pathological [123I]MIBG, olfactory function worsened (mainly due to threshold and discrimination subscores) from baseline to follow-up (p = 0.005). Olfaction was more impaired in subjects with pathological [123I]MIBG compared to those with normal [123I]MIBG at baseline (p = 0.001) and follow-up (p < 0.001). UPDRS-III scores increased in subjects with both pathological [123I]MIBG and [123I]FP-CIT-SPECT. In this group, seven subjects phenoconverted to PD, all- except for one- presented with at least moderate hyposmia at baseline.

CONCLUSION

A combination of the biomarkers "pathological [123I]MIBG" and "hyposmia" likely identifies iRBD patients in an early prodromal stage of PD/DLB, i.e., before nigrostriatal degeneration is visualized. One-third of the subjects with pathological [123I]MIBG had a normal [123I]FP-CIT-SPECT. Noteworthy, in iRBD subjects with pathological [123I]MIBG, olfactory impairment is progressive independent of the [123I]FP-CIT-SPECT status.

Vortioxetine in major depressive disorder: from mechanisms of action to clinical studies. An updated review

INTRODUCTION

Vortioxetine is a multimodal-acting antidepressant that provides improvements on cognitive function aside from antidepressants and anxiolytic effects. Vortioxetine has been found to be one of the most effective and best tolerated options for major depressive disorder (MDD) in head-to-head trials.

AREAS COVERED

The present review intends to gather the most relevant and pragmatic data of vortioxetine in MDD, specially focusing on new studies that emerged between 2015 and 2020.

EXPERT OPINION

Vortioxetine is the first antidepressant that has shown improvements both in depression and cognitive symptoms, due to the unique multimodal mechanism of action that combine the 5-HT reuptake inhibition with modulations of other key pre- and post-synaptic 5-HT receptors (agonism of 5-HT_1A receptor, partial agonism of 5-HT_1B receptor, and antagonism of 5-HT₃, 5-HT_1D and 5-HT₇ receptors). This new mechanism of action can explain the dose-dependent effect and can be responsible for its effects on cognitive functioning and improved tolerability profile. Potential analgesic and anti-inflammatory properties observed in preclinical studies as well as interesting efficacy and tolerability results of clinical studies with specific target groups render it a promising therapeutic option for patients with MDD and concomitant conditions (as menopause symptoms, pain, inflammation, apathy, sleep and/or metabolic abnormalities).

Louis EK. Abnormal rapid eye movement sleep atonia control in chronic post-traumatic stress disorder

STUDY OBJECTIVES

Post-traumatic stress disorder (PTSD) and rapid eye movement (REM) sleep behavior disorder (RBD) share some common features including prominent nightmares and sleep disturbances. We aimed to comparatively analyze REM sleep without atonia (RSWA) between patients with chronic PTSD with and without dream enactment behavior (DEB), isolated RBD (iRBD), and controls.

METHODS

In this retrospective study, we comparatively analyzed 18 PTSD with DEB (PTSD+DEB), 18 PTSD without DEB, 15 iRBD, and 51 controls matched for age and sex. We reviewed medical records to determine PTSD clinical features and quantitatively analyzed RSWA. We used nonparametric analyses to compare clinical and polysomnographic features.

RESULTS

PTSD patients, both with and without DEB, had significantly higher RSWA than controls (all p < .025, excepting submentalis phasic duration in PTSD+DEB). Most RSWA measures were also higher in PTSD+DEB than in PTSD without DEB patients (all p < .025).

CONCLUSIONS

PTSD patients have higher RSWA than controls, whether DEB is present or not, indicating that REM sleep atonia control is abnormal in chronic PTSD. Further prospective studies are needed to determine whether neurodegenerative risk and disease markers similar to RBD might occur in PTSD patients.

Cutaneous α-synuclein is correlated with autonomic impairment in isolated rapid eye movement sleep behavior disorder

STUDY OBJECTIVES

To define the clinical implications of cutaneous phosphorylated α-synuclein (p-syn) and its association with subjective and objective measures of autonomic impairment and clinical features including antidepressant use in isolated rapid eye movement (REM) sleep behavior disorder (iRBD).

METHODS

Twenty-five iRBD patients had quantified neurological and cognitive examinations, olfactory testing, questionnaires, autonomic function testing, and 3 punch skin biopsies (distal thigh, proximal thigh, neck). Skin biopsies were stained for the pan-axonal marker PGP 9.5 and co-stained with p-syn, and results were compared to 28 patients with Parkinson's disease (PD) and 18 healthy controls. Equal numbers of iRBD patients on and off antidepressants were recruited. The composite autonomic severity scale (CASS) was calculated for all patients.

RESULTS

P-syn was detected in 16/25 (64%) of iRBD patients, compared to 27/28 (96%) of PD and 0/18 controls. The presence of p-syn at any biopsy site was correlated with both sympathetic (CASS adrenergic r = 0.6, p < 0.05) and total autonomic impairment (CASS total r = 0.6, p < 0.05) on autonomic reflex testing in iRBD patients. These results were independent of the density of p-syn at each site. There was no correlation between p-syn and antidepressant use.

CONCLUSIONS

In patients with iRBD, the presence of cutaneous p-syn was detected in most patients and was associated with greater autonomic dysfunction on testing. Longitudinal follow-up will aid in defining the predictive role of both skin biopsy and autonomic testing in determining phenoconversion rates and future disease status.

Neurophysiological Aspects of REM Sleep Behavior Disorder (RBD): A Narrative Review

REM sleep without atonia (RSWA) is the polysomnographic (PSG) hallmark of rapid eye movement (REM) sleep behavior disorder (RBD), a feature essential for the diagnosis of this condition. Several additional neurophysiological aspects of this complex disorder have also recently been investigated in depth, which constitute the focus of this narrative review, together with RSWA. First, we describe the complex neural network underlying REM sleep and its muscle atonia, focusing on the disordered mechanisms leading to RSWA. RSWA is then described in terms of its polysomnographic features, and the methods (visual and automatic) currently available for its scoring and quantification are exposed and discussed. Subsequently, more recent and advanced neurophysiological features of RBD are described, such as electroencephalography during wakefulness and sleep, transcranial magnetic stimulation, and vestibular evoked myogenic potentials. The role of the assessment of neurophysiological features in the study of RBD is then carefully discussed, highlighting their usefulness and sensitivity in detecting neurodegeneration in the early or prodromal stages of RBD, as well as their relationship with other proposed biomarkers for the diagnosis, prognosis, and monitoring of this condition. Finally, a future research agenda is proposed to help clarify the many still unclear aspects of RBD.

Neurophysiological Aspects of REM Sleep Behavior Disorder (RBD): A Narrative Review

REM sleep without atonia (RSWA) is the polysomnographic (PSG) hallmark of rapid eye movement (REM) sleep behavior disorder (RBD), a feature essential for the diagnosis of this condition. Several additional neurophysiological aspects of this complex disorder have also recently been investigated in depth, which constitute the focus of this narrative review, together with RSWA. First, we describe the complex neural network underlying REM sleep and its muscle atonia, focusing on the disordered mechanisms leading to RSWA. RSWA is then described in terms of its polysomnographic features, and the methods (visual and automatic) currently available for its scoring and quantification are exposed and discussed. Subsequently, more recent and advanced neurophysiological features of RBD are described, such as electroencephalography during wakefulness and sleep, transcranial magnetic stimulation, and vestibular evoked myogenic potentials. The role of the assessment of neurophysiological features in the study of RBD is then carefully discussed, highlighting their usefulness and sensitivity in detecting neurodegeneration in the early or prodromal stages of RBD, as well as their relationship with other proposed biomarkers for the diagnosis, prognosis, and monitoring of this condition. Finally, a future research agenda is proposed to help clarify the many still unclear aspects of RBD.

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.