Fight or flight? Dream content during sleepwalking/sleep terrors vs rapid eye movement sleep behavior disorder

ObjectiveDreams enacted during sleepwalking or sleep terrors (SW/ST) may differ from those enacted during rapid eye movement sleep behavior disorder (RBD).MethodsSubjects completed aggression, depression, and anxiety questionnaires. The mentations associated with SW/ST and RBD behaviors were collected over their lifetime and on the morning after video polysomnography (PSG). The reports were analyzed for complexity, length, content, setting, bizarreness, and threat.ResultsNinety-one percent of 32 subjects with SW/ST and 87.5% of 24 subjects with RBD remembered an enacted dream (121 dreams in a lifetime and 41 dreams recalled on the morning). These dreams were more complex and less bizarre, with a higher level of aggression in the RBD than in SW/ST subjects. In contrast, we found low aggression, anxiety, and depression scores during the daytime in both groups. As many as 70% of enacted dreams in SW/ST and 60% in RBD involved a threat, but there were more misfortunes and disasters in the SW/ST dreams and more human and animal aggressions in the RBD dreams. The response to these threats differed, as the sleepwalkers mostly fled from a disaster (and 25% fought back when attacked), while 75% of RBD subjects counterattacked when assaulted. The dreams setting included their bedrooms in 42% SW/ST dreams, though this finding was exceptional in the RBD dreams.ConclusionDifferent threat simulations and modes of defense seem to play a role during dream-enacted behaviors (e.g., fleeing a disaster during SW/ST, counterattacking a human or animal assault during RBD), paralleling and exacerbating the differences observed between normal dreaming in nonrapid eye movement (NREM) vs rapid eye movement (REM) sleep.     

Parasomnia overlap disorder: a distinct pathophysiologic entity or a variant of rapid eye movement sleep behavior disorder? A case series

Background

Parasomnia overlap disorder (POD) currently is classified by the International Classification of Sleep Disorders, Second Edition (ICSD-2) as a variant of rapid eye movement (REM) sleep behavior disorder (RBD), and therefore its diagnosis also implies counseling the patients on the increased risk for developing neurodegenerative disorders. POD pathophysiology is not clear to date.

Methods

The authors report 5 cases of POD, review the literature, and analyze previously published cases of POD.

Results

In all 5 reported cases sleep-related activity was clearly demonstrated, though the RBD component was mild or incidentally discovered. None of the patients had Parkinsonian clinical features. Based on ICSD-2 criteria, there are 139 more POD cases reported in the literature and 69. 2% are idiopathic. The POD patients had an earlier age of onset than the patients with RBD. The RBD component was milder than the disorder of arousal (DOA) in most cases. Recently an updated classification was published, which included new categories of POD. The features mentioned above and the revised classification suggests that POD is not just a subtype of RBD.

Conclusions

We propose that POD is a distinct pathophysiologic parasomnia. Further research to identify the underlying mechanism is needed. Proper counseling is necessary for patients presenting with POD at a young age of onset.     

Characteristics of early- and late-onset rapid eye movement sleep behavior disorder in China: a case–control study

ObjectiveTo investigate demography and clinic and polysomnographic characteristics in Chinese rapid eye movement (REM) sleep behavior disorder (RBD) patients across onset ages.MethodsNinety consecutive patients fulfilling the criteria for RBD were recruited for study in our sleep center. Patients were separated into early- and late-onset groups according to age when symptoms began (⩽50 and >50 years, respectively). Ninety age- and gender-matched healthy subjects served as controls. All subjects were interviewed for their clinical history, completed an RBD questionnaire, and underwent an overnight video polysomnography assessment. Demographics, comorbidities, scores on the RBD questionnaire, sleep architecture, and EMG activity were compared between the patients and controls and between the early- and late-onset groups.ResultsOf all RBD patients, 63 were male, and mean age of RBD onset was 54.3 ± 15.7 years. In 25 patients (28%), RBD was secondary and associated with neurodegenerative disease, narcolepsy or antidepressant use. Twenty-three patients (26%) had early-onset RBD and 67 (74%) were in the late-onset group. RBD patients had significantly more comorbidities, dreams and dream-enacting behaviors, and poorer sleep quality than did controls. The early-onset group had a high proportion of females (48%) and an increased proportion of cases associated with narcolepsy. The early-onset group also had fewer movements, lower EMG activity during REM sleep, and better sleep quality when compared to the late-onset group. EMG activity was positively correlated with age of onset. The mean follow-up time was 1.57 ± 0.82 years, and four patients in the late-onset group were subsequently diagnosed with neurodegenerative diseases.ConclusionsStratifying patients into early and late-onset RBD revealed different characteristics from those previously described as typical for RBD. EMG activity during REM sleep was positively correlated with age of onset. We suggest that it will be valuable to explore the relationship between age of onset conversion and neurodegenerative diseases.     

Sex differences in brain atrophy and cognitive impairment in Parkinson’s disease patients with and without probable rapid eye movement sleep behavior disorder

Journal of Neurology - The presence of rapid eye movement sleep behavior disorder (RBD) contributes to increase cognitive impairment and brain atrophy in Parkinson’s disease (PD), but the...     

Does rapid eye movement sleep behavior disorder exist in psychiatric populations? A clinical and polysomnographic case–control study

ObjectivesRapid eye movement (REM) sleep behavior disorder (RBD) has been increasingly reported in patients with psychiatric disorders (pRBD). Although a close association with the usage of psychotropics has been postulated, it remains elusive whether psychotropics are the only causative factor of RBD symptoms in psychiatric populations. Moreover, there is limited literature documenting and quantifying the clinical and polysomnographic features in this population.MethodsA case–control study comparing the clinical and polysomnographic features of 31 pRBD patients with: (1) Age-, sex-, and psychiatric diagnoses-matched controls; and (2) Typical idiopathic RBD (tRBD) patients.ResultsDespite being prescribed with similar psychotropics, pRBD patients had more dream-enacting behaviors (p < 0.01), sleep-related injuries (p < 0.01), and nightmares (p < 0.01) than the psychiatric controls. pRBD patients were younger with more females, but they had comparable sleep-related injuries to tRBD. Both tRBD and pRBD had more REM-related muscle activity than controls (p < 0.01) and the effect remained significant after adjusting for age, gender, and use of antidepressants.ConclusionsOur study suggests that pRBD had comparable clinical features and consequences to those of tRBD. The occurrence of RBD symptoms in these patients may be related to a constellation of factors, including individual predisposition, depressive illness, antidepressants, and other clinical factors. Given the association of RBD and neurodegeneration in tRBD, further prospective follow-up of these patients is warranted.     

Does clinical rapid eye movement behavior disorder predict worse outcomes in Parkinson’s disease?

Our purpose of this study was to investigate whether clinical rapid eye movement sleep behavior disorder (RBD) is indicative of more widespread degenerative changes in Parkinson’s disease (PD), using a longitudinal cohort. In 2005 and 2007, we prospectively collected clinical and treatment characteristics of 61 consecutive patients with PD. The presence of RBD was assessed by spouse interview. Sixty-four percent of patients had clinical RBD in 2005, versus 52% of patients in 2007. The yearly incidence rate of clinical RBD onset was 9%, while clinical RBD disappeared in 14% of patients per year. The motor disability scores (when treated) were worse in patients with than without clinical RBD in 2005, but not in 2007. There was no difference between groups for frequency of freezing, falls, and hallucinations, or for scores on the depression scale, sleepiness scale, mini-mental state examination and frontal assessment battery at the beginning versus the end of the study. Patients with clinical RBD were disabled earlier than patients without RBD, but there was no specific worsening in the RBD group with time, either for motor or non-motor symptoms. The fluctuation and disappearance of clinical RBD in some patients may be due to functional abnormalities rather than lesions.     

REM sleep behavior disorder in Japanese patients with Parkinson’s disease: a multicenter study using the REM sleep behavior disorder screening questionnaire

REM sleep behavior disorder (RBD) is known to be observed more frequently in patients with an α-synucleinopathy such as Parkinson's disease (PD) than in the general population. The precise prevalence of RBD in Japanese PD patients is not known. Therefore, we investigated the prevalence and the clinical characteristics of patients with RBD in a large population of Japanese patients with PD. We investigated various clinical features and employed the Japanese version of the RBD screening questionnaire on 469 non-demented Japanese PD patients in this multicenter study. Probable or possible RBD was detected in 146 patients (31.1%) and was significantly associated with longer PD duration, higher Hoehn and Yahr stage, higher Unified Parkinson's Disease Rating Scale part III subscale (7 items), more motor fluctuations, and a higher levodopa-equivalent daily dose (p < 0.01). As to the major autonomic dysfunctions, severe constipation was significantly more frequent in PD patients with RBD than in those without it (p < 0.01). The RBD symptoms of 53 patients (39.0%) preceded the onset of PD motor symptoms. The median interval from the onset of RBD symptoms to PD motor symptoms was 17.5 years, and 3 patients had intervals of over 50 years. This large-scale multicenter study revealed that RBD is a frequent non-motor symptom in Japanese patients with PD, which may precede the onset of motor symptoms. Moreover, RBD that increases with the duration and severity of PD may be associated with autonomic dysfunction.     

Sleep alterations in mammals: Did aquatic conditions inhibit rapid eye movement sleep?

Sleep has been studied widely in mammals and to some extent in other vertebrates.Higher vertebrates such as birds and mammals have evolved an inimitable rapid eye movement(REM) sleep state.During REM sleep,postural muscles become atonic and the temperature regulating machinery remains suspended.Although REM sleep is present in almost all the terrestrial mammals,the aquatic mammals have either radically reduced or completely eliminated REM sleep. Further,we found a significant negative correlation between REM sleep and the adaptation of the organism to live on land or in water.The amount of REM sleep is highest in terrestrial mammals,significantly reduced in semi-aquatic mammals and completely absent or negligible in aquatic mammals.The aquatic mammals are obligate swimmers and have to surface at regular intervals for air.Also,these animals live in thermally challenging environments,where the conductive heat loss is approximately～90 times greater than air.Therefore,they have to be moving most of the time.As an adaptation, they have evolved unihemispheric sleep,during which they can rove as well as rest.A condition that immobilizes muscle activity and suspends the thermoregulatory machinery,as happens during REM sleep,is not suitable for these animals.It is possible that,in accord with Darwin’s theory,aquatic mammals might have abolished REM sleep with time.In this review, we discuss the possibility of the intrinsic role of aquatic conditions in the elimination of REM sleep in the aquatic mammals.     

Decreased sleep spindle density in patients with idiopathic REM sleep behavior disorder and patients with Parkinson’s disease

ObjectiveTo determine whether sleep spindles (SS) are potentially a biomarker for Parkinson’s disease (PD).MethodsFifteen PD patients with REM sleep behavior disorder (PD + RBD), 15 PD patients without RBD (PD − RBD), 15 idiopathic RBD (iRBD) patients and 15 age-matched controls underwent polysomnography (PSG). SS were scored in an extract of data from control subjects. An automatic SS detector using a Matching Pursuit (MP) algorithm and a Support Vector Machine (SVM) was developed and applied to the PSG recordings. The SS densities in N1, N2, N3, all NREM combined and REM sleep were obtained and evaluated across the groups.ResultsThe SS detector achieved a sensitivity of 84.7% and a specificity of 84.5%. At a significance level of α = 1%, the iRBD and PD + RBD patients had a significantly lower SS density than the control group in N2, N3 and all NREM stages combined. At a significance level of α = 5%, PD − RBD had a significantly lower SS density in N2 and all NREM stages combined.ConclusionsThe lower SS density suggests involvement in pre-thalamic fibers involved in SS generation. SS density is a potential early PD biomarker.SignificanceIt is likely that an automatic SS detector could be a supportive diagnostic tool in the evaluation of iRBD and PD patients.