Longitudinal brain changes in Parkinson's disease with severe olfactory deficit

INTRODUCTION

Olfactory dysfunction and REM sleep behavior disorder (RBD) are associated with distinct cognitive trajectories in the course of Parkinson's disease (PD). The underlying neurobiology for this relationship remains unclear but may involve distinct patterns of neurodegeneration. This study aimed to examine longitudinal cortical atrophy and thinning in early-stage PD with severe olfactory deficit (anosmia) without and with concurrent probable RBD.

METHODS

Longitudinal MRI data over four years of 134 de novo PD and 49 healthy controls (HC) from the Parkinson Progression Marker Initiative (PPMI) cohort were analyzed using a linear mixed-effects model. Patients were categorized into those with anosmia by the University of Pennsylvania Smell Identification Test (UPSIT) score ≤ 18 (AO+) and those without (UPSIT score > 18, AO-). The AO+ group was further subdivided into AO+ with probable RBD (AO+RBD+) and without (AO+RBD-) for subanalysis.

RESULTS

Compared to subjects without baseline anosmia, the AO+ group exhibited greater longitudinal declines in both volume and thickness in the bilateral parahippocampal gyri and right transverse temporal gyrus. Patients with concurrent anosmia and RBD showed more extensive longitudinal declines in cortical volume and thickness, involving additional brain regions including the bilateral precuneus, left inferior temporal gyrus, right paracentral gyrus, and right precentral gyrus.

CONCLUSIONS

The atrophy/thinning patterns in early-stage PD with severe olfactory dysfunction include regions that are critical for cognitive function and could provide a structural basis for previously reported associations between severe olfactory deficit and cognitive decline in PD. Concurrent RBD might enhance the dynamics of cortical changes.

α-synuclein antibody 5G4 identifies idiopathic REM-sleep behavior disorder in abdominal skin biopsies

INTRODUCTION

Idiopathic REM-sleep behavior disorder (iRBD) is considered the most specific prodromal marker of Parkinson's disease (PD). With the need to improve early detection of prodromal α-synucleinopathies, several methods to identify peripheral α-synuclein (α-syn) pathology have been exploited in manifest and prodromal PD with varying diagnostic accuracy. Recently, a disease specific 5G4 antibody has been evaluated in skin biopsies of manifest PD patients. The aim of our study was to analyze the 5G4 α-syn immunoreactivity in skin biopsies of deeply phenotyped subjects with iRBD and controls.

METHODS

The study cohort consisted of 28 patients with PD, 24 subjects with iRBD and 27 healthy controls, recruited from the CEGEMOD, PDBIOM and PARCAS cohorts. All subjects were deeply phenotyped and assessed for prodromal PD (pPD) probability based on MDS research criteria. Abdominal skin punch biopsies were processed and stained using a conformation specific 5G4 α-syn antibody as well as axonal markers SMI-31 and S100.

RESULTS

5G4-positivity was identified in 23/28 PD patients, 20/24 iRBD subjects and 8/27 healthy controls. Compared to healthy controls, sensitivity and specificity reached 83.33 % and 70.37 % for iRBD; and 82.14 % and 70.37 % for PD, respectively. 5G4-positivity rate in our study was irrespective of the calculated pPD probability of iRBD subjects.

CONCLUSIONS

This work establishes the diagnostic yield of conformation specific 5G4 α-syn antibody testing in skin biopsies of subjects with pPD, specifically iRBD. The diagnostic accuracy for this method seems to be similar for both manifest and prodromal PD and is not dependent on the pPD probability ratios.

Reduced Gastric Contraction in Rapid-Eye-Movement Sleep Behavior Disorder and De Novo Parkinson's Disease

BACKGROUND

Reduced gastric motility in Parkinson's disease (PD) has been reported, but hardly any study exists in subjects with isolated rapid-eye-movement (REM) sleep behavior disorder (iRBD), a specific prodrome of α-synucleinopathies.

OBJECTIVES

We compared the gastric motility of 17 iRBD subjects with that of 18 PD subjects (15 drug naive, 3 early treated in defined off) and 15 healthy controls (HC) with real-time magnetic resonance imaging (rtMRI).

METHODS

After overnight fasting, participants consumed a standardized breakfast and underwent a 3-T rtMRI of the stomach. Amplitude and velocity of the peristaltic waves were analyzed under blinded conditions. Gastric motility index (GMI) was calculated. The procedure was repeated in 12 of 17 iRBD subjects ~2.5 years later. Nine of these 12 iRBD subjects were hyposmic.

RESULTS

In iRBD and PD subjects the amplitude of the peristaltic waves was significantly reduced compared with HCs (iRBD vs. HC: 8.7 ± 3.7 vs. 11.9 ± 4.1 mm, P = 0.0097; PD vs. HC: 6.8 ± 2.2 vs. 11.9 ± 4.1 mm, P = 0.0001). The amplitude in iRBD and PD subjects was decreased to the same extent. The GMI was reduced in only PD subjects (PD vs. HC: P = 0.0027; PD vs. iRBD: P = 0.0203). After ~2.5 years the amplitude in iRBD subjects did not significantly decrease further.

CONCLUSION

The amplitude of the peristaltic waves was markedly reduced in iRBD, a prodrome of α-synucleinopathies. This reduction was similar to the extent observed already in manifest early PD. This finding implies that the α-synuclein pathology affects the innervation of the stomach already in the prodromal stage. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Cerebellar Volume Reduction in Patients with Isolated REM Sleep Behavior Disorder: Evidence of a Potential Role of the Cerebellum

INTRODUCTION

In this study, we aimed to investigate changes in the total cerebellar volume, subdivisions of the cerebellar volume, and intrinsic cerebellar network in patients with isolated rapid eye movement (REM) sleep behavior disorder (iRBD) compared to healthy controls.

METHODS

We enrolled patients with newly diagnosed iRBD and healthy controls who had no structural lesions according to their brain MRI. All participants underwent three-dimensional T1-weighted imaging. We obtained the total cerebellar volume and subdivisions of the cerebellar volume using the ACAPULCO program and calculated the intrinsic cerebellar network using a BRAPH program based on the subdivisions of the cerebellar volume by applying a graph theory. We compared the cerebellar volumes and intrinsic cerebellar network between the patients with iRBD and healthy controls.

RESULTS

In total, we enrolled 43 patients with iRBD and 47 healthy controls. Total cerebellar volume in patients with iRBD was lower than that in the healthy controls (8.4637 vs. 9.0863%, p = 0.0001). There were significant differences in the subdivisions of cerebellar volume between the groups. The volumes of the right and left lobule VIIB in the patients with iRBD were lower than those in the healthy controls (right, 0.3495 vs. 0.4025%, p = 0.0009; left, 0.3561 vs. 0.4293%, p < 0.0001). However, the other cerebellar volumes, such as the corpus meullare and vermis, were not different between the groups. The intrinsic cerebellar network was not different between the patients with iRBD and healthy controls.

CONCLUSION

We found decreased total cerebellar volumes and subdivisions of the cerebellar volume, particularly in the right and left lobule VIIB, in patients with iRBD compared to healthy controls. The present results suggest that the cerebellum may play a potential role in the pathogenesis of iRBD.

Dermal Real-Time Quaking-Induced Conversion Is a Sensitive Marker to Confirm Isolated Rapid Eye Movement Sleep Behavior Disorder as an Early α-Synucleinopathy

BACKGROUND

Skin biopsy is a potential tool for the premortem confirmation of an α-synucleinopathy.

OBJECTIVE

The aim was to assess the aggregation assay real-time quaking-induced conversion (RT-QuIC) of skin biopsy lysates to confirm isolated rapid eye movement sleep behavior disorder (iRBD) as an α-synucleinopathy.

METHODS

Skin biopsies of patients with iRBD, Parkinson's disease (PD), and controls were analyzed using RT-QuIC and immunohistochemical detection of phospho-α-synuclein.

RESULTS

α-Synuclein aggregation was detected in 97.4% of iRBD patients (78.4% of iRBD biopsies), 87.2% of PD patients (70% of PD biopsies), and 13% of controls (7.9% of control biopsies), with a higher seeding activity in iRBD compared to PD. RT-QuIC was more sensitive but less specific than immunohistochemistry.

CONCLUSIONS

Dermal RT-QuIC is a sensitive method to detect α-synuclein aggregation in iRBD, and high seeding activity may indicate a strong involvement of dermal nerve fibers in these patients. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Cholinergic Nucleus 4 Degeneration and Cognitive Impairment in Isolated Rapid Eye Movement Sleep Behavior Disorder

BACKGROUND

Cholinergic nucleus 4 (Ch4) degeneration is associated with cognitive impairment in Parkinson's disease and dementia with Lewy bodies, but it is unknown if Ch4 degeneration is also present in isolated rapid eye movement sleep behavior disorder (iRBD).

OBJECTIVE

The aim was to determine if there is evidence of Ch4 degeneration in patients with iRBD and if it is associated with cognitive impairment.

METHODS

We analyzed the clinical and neuropsychological data of 35 iRBD patients and 35 age- and sex-matched healthy controls. Regional gray matter density (GMD) was calculated for Ch4 using probabilistic maps applied to brain magnetic resonance imaging (MRI).

RESULTS

Ch4 GMD was significantly lower in the iRBD group compared to controls (0.417 vs. 0.441, P = 0.02). Ch4 GMD was also found to be a significant predictor of letter number sequencing (β-coefficient = 58.31, P = 0.026, 95% confidence interval [7.47, 109.15]), a measure of working memory.

CONCLUSIONS

iRBD is associated with Ch4 degeneration, and Ch4 degeneration in iRBD is associated with impairment in working memory. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neuroanatomical Localization of Rapid Eye Movement Sleep Behavior Disorder in Human Brain Using Lesion Network Mapping

OBJECTIVE

To localize the neuroanatomical substrate of rapid eye movement sleep behavior disorder (RBD) and to investigate the neuroanatomical locational relationship between RBD and α-synucleinopathy neurodegenerative diseases.

MATERIALS AND METHODS

Using a systematic PubMed search, we identified 19 patients with lesions in different brain regions that caused RBD. First, lesion network mapping was applied to confirm whether the lesion locations causing RBD corresponded to a common brain network. Second, the literature-based RBD lesion network map was validated using neuroimaging findings and locations of brain pathologies at post-mortem in patients with idiopathic RBD (iRBD) who were identified by independent systematic literature search using PubMed. Finally, we assessed the locational relationship between the sites of pathological alterations at the preclinical stage in α-synucleinopathy neurodegenerative diseases and the brain network for RBD.

RESULTS

The lesion network mapping showed lesions causing RBD to be localized to a common brain network defined by connectivity to the pons (including the locus coeruleus, dorsal raphe nucleus, central superior nucleus, and ventrolateral periaqueductal gray), regardless of the lesion location. The positive regions in the pons were replicated by the neuroimaging findings in an independent group of patients with iRBD and it coincided with the reported pathological alterations at post-mortem in patients with iRBD. Furthermore, all brain pathological sites at preclinical stages (Braak stages 1-2) in Parkinson's disease (PD) and at brainstem Lewy body disease in dementia with Lewy bodies (DLB) were involved in the brain network identified for RBD.

CONCLUSION

The brain network defined by connectivity to positive pons regions might be the regulatory network loop inducing RBD in humans. In addition, our results suggested that the underlying cause of high phenoconversion rate from iRBD to neurodegenerative α-synucleinopathy might be pathological changes in the preclinical stage of α-synucleinopathy located at the regulatory network loop of RBD.

Mediterranean Diet and Parkinson's Disease

Parkinson's disease (PD) is an age-related neurodegenerative disorder, diagnosed on the basis of typical motor disturbances, but also characterized by the presence of non-motor symptoms, such as rapid eye movement (REM)-sleep behavior disorders, olfactory impairment, and constipation, which are often prodromal to the onset of the disease. PD is often associated with the presence of oxidative brain injury and chronic neuroinflammation, with infiltration and accumulation of peripheral immune cells that have been found in affected brain regions of PD patients. Recently, the role of the gut-brain axis in the pathogenesis of PD is getting more and more attention, and several pieces of evidence indicate alterations in the gut microbiota of PD-affected patients. Diet exerts a central role in defining the microbiota composition and different dietetic patterns can result in a higher or lower abundance of specific bacteria that, in turn, can affect gut permeability and express anti- or pro-inflammatory metabolites. In the present review, the effects of the Mediterranean diet in modulating both PD onset and its progression will be considered with a special focus on the antioxidant and anti-inflammatory properties of this dietetic regimen as well as on its effects on the microbiota composition.

Relationship between Substantia Nigra Neuromelanin Imaging and Dual Alpha-Synuclein Labeling of Labial Minor in Salivary Glands in Isolated Rapid Eye Movement Sleep Behavior Disorder and Parkinson's Disease

We investigated the presence of misfolded alpha-Synuclein (α-Syn) in minor salivary gland biopsies in relation to substantia nigra pars compacta (SNc) damage measured using magnetic resonance imaging in patients with isolated rapid eye movement sleep behavior disorder (iRBD) and Parkinson's disease (PD) as compared to healthy controls. Sixty-one participants (27 PD, 16 iRBD, and 18 controls) underwent a minor salivary gland biopsy and were scanned using a 3 Tesla MRI. Deposits of α-Syn were found in 15 (55.6%) PD, 7 (43.8%) iRBD, and 7 (38.9%) controls using the anti-aggregated α-Syn clone 5G4 antibody and in 4 (14.8%) PD, 3 (18.8%) iRBD and no control using the purified mouse anti-α-Syn clone 42 antibody. The SNc damages obtained using neuromelanin-sensitive imaging did not differ between the participants with versus without α-Syn deposits (irrespective of the antibodies and the disease group). Our study indicated that the α-Syn detection in minor salivary gland biopsies lacks sensitivity and specificity and does not correlate with the SNc damage, suggesting that it cannot be used as a predictive or effective biomarker for PD.

The Significance of Rapid Eye Movement Sleep Behavior Disorder in Neurodegenerative Diseases: An Updated Review

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD), a parasomnia, after being diagnosed, can predict the emergence of an alpha-synuclein-associated neurodegenerative disease (NDD) in 20-45% and 92% of patients within 5 and 14 years, respectively. RBD is less common in tauopathies, and the studies to evaluate its association with polyglutamine diseases have been very few.

OBJECTIVE

To revisit our knowledge on the significance of RBD in the emergence of NDDs and to review the recent updates in the potential biomarkers, which can help predict the risk of phenconversion into NDDs in idiopathic RBD (iRBD) patients. We also aimed to look at the potential neuroprotective therapies that can potentially be used earlier in iRBD patients.

METHODS

We conducted a review of the papers, after selecting them from the PubMed database. After a thorough screening, 51 articles were chosen to be included in this review.

RESULTS AND CONCLUSION

The prospective studies showed that the risk of phenoconversion of iRBD into overt NDDs increased over the longer duration of follow up. Magnetic resonance imaging (MRI) findings, Electroencephalographic findings along with subtle motor signs, autonomic dysfunction, impaired olfaction, and color vision, among others, can be used to predict the onset of an NDD in iRBD. Phytocannabinoids showed a possible neuroprotective effect in animal studies. Considering how RBD is the antecedent of NDDs, there is a need for additional studies to better understand the utility of the aforementioned biomarkers and institute potential neuroprotective therapies early in the process.

Rapid Eye Movement Sleep Behavior Disorder and Other Rapid Eye Movement Parasomnias

PURPOSE OF REVIEW

The discovery of rapid eye movement (REM) sleep and, in particular, REM sleep behavior disorder (RBD) have brought elusive nightmarish experiences to scientific scrutiny. This article summarizes a century of sleep research to examine the maladies of dreaming, their pathophysiologic significance, and management.

RECENT FINDINGS

Under healthy physiologic conditions, REM sleep is characterized by vivid mentation combined with skeletal muscle paralysis. The loss of REM sleep atonia in RBD results in vivid, potentially injurious dream enactment to patients and bed partners. RBD is common, affecting at least 1% of the population and is primarily caused by α-synuclein pathology of REM sleep-related brainstem neurons. The majority of patients with RBD ultimately develop a neurodegenerative syndrome such as Parkinson disease, dementia with Lewy bodies, or multiple system atrophy. Among patients with Parkinson disease, RBD predicts an aggressive disease course with rapid cognitive, motor, and autonomic decline. RBD is diagnosed by the presence of dream enactment episodes (either recorded or clinically recalled) and physiologic evidence of REM sleep without atonia demonstrated on polysomnography. Bedroom safety is of paramount importance in the management of RBD while pharmacokinetic options include melatonin or clonazepam.

SUMMARY

The injurious dream enactment of RBD is common and treatable. It is a syndrome of α-synuclein pathology with most patients ultimately developing Parkinson disease, dementia with Lewy bodies, or a related disorder.

Consistent skin α-synuclein positivity in REM sleep behavior disorder - A two center two-to-four-year follow-up study

OBJECTIVE/METHODS

Phosphorylated alpha-synuclein (p-syn) in dermal nerves of patients with isolated REM sleep behavior disorder (iRBD) is detectable by immunofluorescence-labeling. Skin-biopsy-p-syn-positivity was recently postulated to be a prodromal marker of Parkinson's disease (PD) or related synucleinopathies. Here, we provide two-to four-year clinical and skin biopsy follow-up data of 33 iRBD patients, whose skin biopsy findings at baseline were reported in 2017.

RESULTS

Follow-up biopsies were available from 25 patients (18 positive at baseline) and showed consistent findings over time in 24 patients. One patient converted from skin-biopsy-negativity to -positivity. P-syn-positivity was observed in iRBD patients who still had a normal FP-CIT-SPECT two years later. Clinically, five of the 23 at baseline skin-biopsy-positive patients (21.7%) had converted to PD or dementia with Lewy bodies at follow-up, but none of the skin-biopsy-negative patients.

CONCLUSIONS

Dermal p-syn in iRBD is most probably an early consistent marker of synucleinopathy and may support other indicators of conversion to manifest disease state.

REM sleep behavior in Parkinson disease: Frequent, particularly with higher age

This retrospective single-center polysomnography-based study was designed to assess the frequency of REM sleep behavior disorder (RBD) in consecutive patients with Parkinsonism, including Parkinson disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration. We observed RBD in 77% of 540 Parkinson patients, with rising frequency at higher age and regardless of sex, in >89% of 89 patients with dementia with Lewy bodies or multiple system atrophy, and in <15% of 42 patients with progressive supranuclear palsy or corticobasal degeneration. Thus, the prevalence of RBD in sporadic Parkinson disease might be higher than previously assumed, particularly in elderly patients.

Nigrosome 1 imaging in REM sleep behavior disorder and its association with dopaminergic decline

OBJECTIVES

Rapid eye movement sleep behavior disorder (RBD) patients have a high risk of developing a Parkinsonian disorder, offering an opportunity for neuroprotective intervention. Predicting near-term conversion, however, remains a challenge. Dopamine transporter imaging, while informative, is expensive and not widely available. Here, we investigate the utility of susceptibility-weighted MRI (SWI) to detect abnormalities of the substantia nigra in RBD, and explore their association with striatal dopaminergic deficits.

METHODS

SWI of the substantia nigra was performed in 46 RBD patients, 27 Parkinson's patients, and 32 control subjects. Dorsal nigral hyperintensity (DNH) was scored by two blinded raters, and separately quantified using a semiautomated process. Forty-two RBD patients were also imaged with ¹²³ I-ioflupane single-photon emission computed tomography (DaT SPECT/CT).

RESULTS

Consensus visual DNH classification was possible in 87% of participants. 27.5% of RBD patients had lost DNH, compared with 7.7% of control subjects and 96% of Parkinson's patients. RBD patients lacking DNH had significantly lower putamen dopaminergic SPECT/CT activity compared to RBD patients with DNH present (specific uptake ratios 1.89 vs. 2.33, P = 0.002). The mean quantified DNH signal intensity declined in a stepwise pattern, with RBD patients having lower intensity than controls (0.837 vs. 0.877, P = 0.01) but higher than PD patients (0.837 vs. 0.765, P < 0.001).

INTERPRETATION

Over one quarter of RBD patients have abnormal substantia nigra SWI reminiscent of Parkinson's, which is associated with a greater dopaminergic deficit. This modality may help enrich neuroprotective trials with early converters.

Loss of dorsolateral nigral hyperintensity on 3.0 tesla susceptibility-weighted imaging in idiopathic rapid eye movement sleep behavior disorder

We assessed loss of dorsolateral nigral hyperintensity (DNH) on high-field susceptibility-weighted imaging (SWI), a novel magnetic resonance imaging marker for Parkinson's disease (PD), in 15 subjects with idiopathic rapid eye movement sleep behavior disorder (iRBD) and compared findings to 42 healthy controls (HCs) and 104 PD patients. We found loss of DNH in at least two thirds of iRBD subjects, which approaches the rate observed in PD and is in contrast to findings in HCs. We propose that absence of DNH on high-field SWI could identify prodromal degenerative parkinsonism in iRBD. Ann Neurol 2016;79:1026-1030.

Neurodegenerative disorder risk in idiopathic REM sleep behavior disorder: study in 174 patients

OBJECTIVE

To estimate the risk for developing a defined neurodegenerative syndrome in a large cohort of idiopathic REM sleep behavior disorder (IRBD) patients with long follow-up.

METHODS

Using the Kaplan-Meier method, we estimated the disease-free survival rate from defined neurodegenerative syndromes in all the consecutive IRBD patients diagnosed and followed-up in our tertiary referal sleep center between November 1991 and July 2013.

RESULTS

The cohort comprises 174 patients with a median age at diagnosis of IRBD of 69 years and a median follow-up of four years. The risk of a defined neurodegenerative syndrome from the time of IRBD diagnosis was 33.1% at five years, 75.7% at ten years, and 90.9% at 14 years. The median conversion time was 7.5 years. Emerging diagnoses (37.4%) were dementia with Lewy bodies (DLB) in 29 subjects, Parkinson disease (PD) in 22, multiple system atrophy (MSA) in two, and mild cognitive impairment (MCI) in 12. In six cases, in whom postmortem was performed, neuropathological examination disclosed neuronal loss and widespread Lewy-type pathology in the brain in each case.

CONCLUSIONS

In a large IRBD cohort diagnosed in a tertiary referal sleep center, prolonged follow-up indicated that the majority of patients are eventually diagnosed with the synucleinopathies PD, DLB and less frequently MSA. IRBD represented the prodromal period of these conditions. Our findings in IRBD have important implications in clinical practice, in the investigation of the early pathological events occurring in the synucleinopathies, and for the design of interventions with potential disease-modifying agents.

Pathophysiology of REM sleep behaviour disorder and relevance to neurodegenerative disease

REM sleep behaviour disorder (RBD) is a parasomnia characterized by the loss of normal skeletal muscle atonia during REM sleep with prominent motor activity accompanying dreaming. The terminology relating to RBD, and mechanisms underlying REM sleep without atonia and RBD based on data in cat and rat are presented. Neuroimaging data from the few published human cases with RBD associated with structural lesions in the brainstem are presented, in which the dorsal midbrain and pons are implicated. Pharmacological manipulations which alter RBD frequency and severity are reviewed, and the data from human neuropathological studies are presented. An anatomic framework and new schema for the pathophysiology of RBD are proposed based on recent data in rat regarding the putative flip-flop switch for REM sleep control. The structure in man analogous to the subcoeruleus region in cat and sublaterodorsal nucleus in rat is proposed as the nucleus (and its associated efferent and afferent pathways) crucial to RBD pathophysiology. The association of RBD with neurological disease ('secondary RBD') is presented, with emphasis on RBD associated with neurodegenerative disease, particularly the synucleinopathies. The hypothesized pathophysiology of RBD is presented in relation to the Braak staging system for Parkinson's disease, in which the topography and temporal sequence of synuclein pathology in the brain could explain the evolution of parkinsonism and/or dementia well after the onset of RBD. These data suggest that many patients with 'idiopathic' RBD are actually exhibiting an early clinical manifestation of an evolving neurodegenerative disorder. Such patients may be appropriate for future drug therapies that affect synuclein pathophysiology, in which the development of parkinsonism and/or dementia could be delayed or prevented. We suggest that additional clinicopathological studies be performed in patients with dementia or parkinsonism, with and without RBD, as well as in patients with idiopathic RBD, to further elucidate the pathophysiology and also characterize the clinical and pathophysiological relevance of RBD in neurodegenerative disease. Furthermore, longitudinal studies in patients with idiopathic RBD are warranted to characterize the natural history of such patients and prepare for future therapeutic trials.

A unique episode of REM sleep behavior disorder triggered during surgery for Parkinson's disease

REM sleep behavior disorder (RBD) is characterized by vigorous movements during REM sleep. Here, the authors report the case of a patient who presented such a disorder immediately after the implantation of the definitive electrode for left subthalamic stimulation. Interestingly, this was and has remained a unique episode in his medical history. It was found that a microlesion in or near the upper part of the pars compacta of the substantia nigra was very likely responsible for this phenomenon.

Absence of rapid eye movement sleep behavior disorder in 11 members of the pallidopontonigral degeneration kindred

BACKGROUND

Rapid eye movement sleep behavior disorder (RBD) is a parasomnia that is manifested by dream enactment behavior. The electrophysiologic substrate for RBD on polysomnography is rapid eye movement sleep without atonia. Rapid eye movement sleep behavior disorder likely stems from neuronal network dysfunction in the brainstem, although it is not yet clear which specific networks are involved. Rapid eye movement sleep behavior disorder is often associated with the sporadic synucleinopathies but rarely associated with the sporadic tauopathies. There are no reports on the possible association of rapid eye movement sleep without atonia and RBD with any familial tauopathy.

OBJECTIVE

To characterize the clinical sleep and polysomnography features in a kindred with a familial tauopathy.

METHODS

We performed standard polysomnography in 11 members of the pallidopontonigral degeneration kindred irrespective of any sleep-related complaints. Neuropathologic findings were analyzed in those who subsequently underwent autopsy.

RESULTS

Six affected and 5 genealogically at-risk family members were studied. None of the 11 had a history of dream enactment behavior. Nine of the 11 members attained sufficient rapid eye movement sleep on polysomnography, and the electrophysiologic features of rapid eye movement sleep without atonia and behavioral manifestations of RBD were absent in all subjects. Neuropathologic examination of 4 affected individuals revealed marked nigral degeneration in 3 along with mild degenerative changes in the locus coeruleus, pontine nuclei and tegmentum, and medullary tegmentum.

CONCLUSIONS

These findings argue against nigral degeneration being the primary cause of RBD. The absence of the historical, electrophysiologic, and behavioral manifestations of RBD in this kindred provides further evidence that RBD is rare in the sporadic and familial tauopathies. The difference in frequencies of RBD associated with the synucleinopathies compared with the tauopathies suggests differences in the selective vulnerability of brainstem circuits between the synucleinopathies and tauopathies.

Impaired rapid eye movement sleep in the Tg2576 APP murine model of Alzheimer's disease with injury to pedunculopontine cholinergic neurons

Impaired rapid eye movement sleep (REMS) is commonly observed in Alzheimer's disease, suggesting injury to mesopontine cholinergic neurons. We sought to determine whether abnormal beta-amyloid peptides impair REMS and injure mesopontine cholinergic neurons in transgenic (hAPP695.SWE) mice (Tg2576) that model brain amyloid pathologies. Tg2576 mice and wild-type littermates were studied at 2, 6, and 12 months by using sleep recordings, contextual fear conditioning, and immunohistochemistry. At 2 months of age, REMS was indistinguishable by genotype but was reduced in Tg2576 mice at 6 and 12 months. Choline acetyltransferase-positive neurons in the pedunculopontine tegmentum of Tg2576 mice at 2 months evidenced activated caspase-3 immunoreactivity, and at 6 and 12 months the numbers of pedunculopontine tegmentum choline acetyltransferase-positive neurons were reduced in the Tg2576 mice. Other cholinergic groups involved in REMS were unperturbed. At 12 months, Tg2576 mice demonstrated increased 3-nitrotyrosine immunoreactivity in cholinergic projection sites but not in cholinergic soma. We have identified a population of selectively compromised cholinergic neurons in young Tg2576 mice that manifest early onset REMS impairment. The differential vulnerability of these cholinergic neurons to Abeta injury provides an invaluable tool with which to understand mechanisms of sleep/wake perturbations in Alzheimer's disease.

Brainstem 1H-MR spectroscopy in patients with Parkinson's disease with REM sleep behavior disorder and IPD patients without dream enactment behavior

OBJECTIVES

The objective of our study was to evaluate brainstem involvement by 1H-MR spectroscopy (1H-MRS) method in patients with idiopathic Parkinson's disease (IPD) with REM sleep behavior disorder (RBD) and IPD without dream enactment behavior.

PATIENTS AND METHODS

We prospectively studied 12 IPD (3 females, 9 males) with a clinically and electrophysiologically confirmed RBD and 12 IPD (3 females, 9 males) patients without dream enactment behavior followed in Outpatient Clinics for Movement Disorders of Department of Neurology, Haseki Hospital. Using long and short TE single voxel 1H-MRS directed at ventral and dorsal pons, long TE NAA/Cr, Ch/Cr and short TE NAA/Cr, Ch/Cr, MI/Cr values of both groups were compared.

RESULTS

Although no difference was found between groups with RBD and IPD without dream enactment behavior in demographic characteristics, duration of disease, mean levodopa dosage and duration of levodopa use, all UPDRS scores (total, motor and cognitive) were worse in RBD group (p<0.05). There was no statistically significant difference in long TE NAA/Cr, Ch/Cr and short TE NAA/Cr, Ch/Cr, MI/Cr values obtained in both groups (p>0.05).

CONCLUSION

1H-MRS does not detect marked metabolic differences in the pons in subjects with IPD with RBD and IPD without dream enactment behavior. This finding suggests either that present methodologies are not sensitive to detect subtle metabolic changes in the pons of subjects with RBD or that the primary lesion of RBD exists in other REM sleep-related brain regions beyond the pons such as the substantia nigra, the basal ganglia or the limbic system.

Rem sleep without atonia--from cats to humans

Basic science research observations often lead to unexpected surprises. It is likely that in 1965 when Dr. Michel Jouvet placed bilateral peri-locus coeruleus lesions in cats and observed REM sleep without atonia (RWA) and "oneiric" behavior that could only be explained by "acting out dreams" (or "dreaming out acts"), he recognized that it was an important observation, but had little inkling of its true significance. Nor could he even imagine that it would lead to such greater understanding of wake/sleep phenomena in humans. Likely also, the first observation of REM sleep behavior disorder (RBD) in humans was felt to be interesting and novel - again with no true appreciation of what this seemingly simple observation would lead to important clinical relationships with numerous neurodegenerative disorders. The identification of RBD in humans also buttressed the concept of state dissociation, which has served to explain many previously unexplainable human behavioral phenomena.

Synucleinopathy pathology and REM sleep behavior disorder plus dementia or parkinsonism

OBJECTIVE

To determine if synucleinopathy pathology is related to REM sleep behavior disorder (RBD) plus dementia or parkinsonism.

METHODS

The clinical and neuropathologic findings were analyzed on all autopsied cases evaluated at Mayo Clinic Rochester from January 1990 to April 2002 who were diagnosed with RBD and a neurodegenerative disorder. Ubiquitin and/or alpha-synuclein immunocytochemistry was used in all cases. The clinical and neuropathologic diagnoses were based on published criteria.

RESULTS

Fifteen cases were identified (14 men). All had clear histories of dream enactment behavior, and 10 had RBD confirmed by polysomnography. RBD preceded dementia or parkinsonism in 10 (66.7%) patients by a median of 10 (range 2 to 29) years. The clinical diagnoses included dementia with Lewy bodies (DLB) (n = 6); multiple-system atrophy (MSA) (n = 2); combined DLB, AD, and vascular dementia (n = 1); dementia (n = 1); dementia with parkinsonism (n = 1); PD (n = 1); PD with dementia (n = 1); dementia/parkinsonism/motor neuron disease (n = 1); and AD/Binswanger's disease (n = 1). The neuropathologic diagnoses were Lewy body disease (LBD) in 12 (neocortical in 11 and limbic in 1) and MSA in 3. Three also had argyrophilic grain pathology. In the LBD cases, concomitant AD pathology was present in six (one also with Binswanger's pathology, and one also with multiple subcortical infarcts).

CONCLUSION

In the setting of degenerative dementia or parkinsonism, RBD often reflects an underlying synucleinopathy.

Physiological and anatomical link between Parkinson-like disease and REM sleep behavior disorder

Parkinson's disease (PD) is a progressive neurodegenerative disease that is caused by a loss of neurons in the ventral midbrain. Parkinsonian patients often experience insomnia, parasomnias, and daytime somnolence. REM sleep behavior disorder (RBD) is characterized by vigorous movements during REM sleep, and may also be caused by neuronal degeneration in the central nervous system (CNS); however, the site of degeneration remains unclear. Both Parkinsonism and RBD become more prevalent with aging, with onset usually occurring in the sixties. Recent findings show that many individuals with RBD eventually develop Parkinsonism. Conversely, it is also true that certain patients diagnosed with Parkinsonism subsequently develop RBD. Postmortem examination reveals that Lewy bodies, Lewy neurites, and alpha-synuclein are found in brainstem nuclei in both Parkinsonism and RBD patients. In this article, we will discuss evidence that Parkinsonism and RBD are physiologically and anatomically linked, based on our animal experiments and other studies on human patients.

Sexual behavior in sleep, sleepwalking and possible REM behavior disorder: a case report

Seven cases of sexual behavior during sleep (SBS) have been recently reported. The subjects had histories of behavioral parasomnias as well as positive family histories of parasomnia. A 27 year-old man with a history of sexual behavior during sleep was reported. His sleep history disclosed sleepwalking (SW) since 9 years of age. He also developed episodes of highly disruptive and violent nocturnal behavior with dream enactment at age 20 years, which often resulted in physical injuries either to himself or his wife and infant. His wife also reported episodes of amnestic sexual behavior that began 4 years before referral. During the episodes, the patient typically procured his wife, achieving complete sexual intercourse with total amnesia. Physical and neurological diagnostic workups were unremarkable. Family history disclosed sleepwalking in his brother. He was put on 2mg/day of bedtime clonazepam with a remarkable clinical improvement. This case involves either the combination of violent and non-violent sleepwalking with SBS, or the superimposition of presumed REM sleep behavior disorder (RBD) on top of preexisting SW in a man who also developed SBS in adulthood. Thus, this is a case report of probable parasomnia overlap syndrome.