Non-REM sleep with hypertonia in Parkinsonian Spectrum Disorders: A pilot investigation

Autonomic dysregulation during sleep in Parkinsonian spectrum disorders - A proof of concept

INTRODUCTION

Autonomic dysfunction is common in α-synucleinopathies such as Lewy Body dementias (LBD), Parkinson's disease (PD), and isolated REM Sleep Behavior Disorder (iRBD). We analyzed pulse-rate changes during sleep to index autonomic nervous system (ANS) dysfunction in patients with α-synucleinopathies vs. non-synucleinopathy groups expected to have normal ANS function.

METHODS

Patients with LBD (n = 16), PD (PD, n = 14) or iRBD (n = 12) were compared to the non-synucleinopathy groups Alzheimers disease dementia (ADem, n = 26), mild cognitive impairment (MCI, n = 34) or controls (CG, n = 54). Sleep Profiler was used to derive a sleep autonomic activation index (AAI), i.e., ≥6 beat-per-minute increase/decrease, pulse rate coefficient of variation (PR-CV), and automated sleep staging with sleep-spindles and non-REM hypertonia (NRH). Analysis included statistical group comparisons and receiver operating characteristics curves to determine optimal classification of groups.

RESULTS

AAI and PR-CV were moderately correlated across all recordings (rs = 0.58, P < 0.0001), except in the LBD and PD groups. AAI but not PR-CV differentiated the LBD, PD and iRBD from non-Parkinsonian groups. AAI was decreased in LBD and PD patients compared to the CG (p < 0.003) and MCI (p < 0.03). AAI decreased based on age and its receiver operating characteristic area under the curve ranged from 0.63 to 0.75. AAI had a weak negative correlation to NRH (rs ≤ -0.26) but not sleep-spindles.

CONCLUSION

Synucleinopathy-related ANS dysfunction can reasonably discriminate prodromal and manifest PD/LBD diseased groups from non-synucleinopathies. Further studies incorporating AAI into a multivariate classifier of neurodegenerative disorders based on sleep characteristics acquired in the patient's home are planned.

Louis EK. Proof-of-concept for characterization of neurodegenerative disorders utilizing two non-REM sleep biomarkers

Study objective

This proof-of-concept study aimed to determine whether the combined features of two non-rapid eye movement (NREM) sleep biomarkers acquired predominantly in-home could characterize different neurodegenerative disorders.

Methods

Sleep spindle duration and non-REM hypertonia (NRH) were evaluated in seven groups including a control group (CG = 61), and participants with isolated REM sleep behavior disorder (iRBD = 19), mild cognitive impairment (MCI = 41), Parkinson disease (PD = 16), Alzheimer disease dementia (ADem = 29), dementia with Lewy Bodies or Parkinson disease dementia (LBD = 19) and progressive supranuclear palsy (PSP = 13). One-way analysis of variance (ANOVA), Mann-Whitney U, intra-class (ICC) and Spearman ranked correlations, Bland-Altman plots and Kappa scores, Chi-square and Fisher exact probability test, and multiple-logistic regression were focused primarily on spindle duration and NRH and the frequencies assigned to the four normal/abnormal spindle duration/NRH combinations.

Results

ANOVA identified group differences in age, sleep efficiency, REM, NRH (p < 0.0001) and sleep time (p = 0.015), Spindle duration and NRH each demonstrated good night-to-night reliabilities (ICC = 0.95 and 0.75, Kappa = 0.93 and 0.66, respectively) and together exhibited an association in the PD and LBD groups only (p < 0.01). Abnormal spindle duration was greater in records of PSP (85%) and LBD (84%) patients compared to CG, MCI, PD and ADem (p < 0.025). Abnormal NRH was greater in PSP = 92%, LBD = 79%, and iRBD = 74% compared to MCI = 32%, ADem = 17%, and CG = 16% (p < 0.005).The combination biomarker normal spindle duration/normal NRH was observed most frequently in CG (56%) and MCI (41%). ADem most frequently demonstrated normal spindle duration/normal NRH (45%) and abnormal spindle duration/normal NRH (38%). Normal spindle duration/abnormal NRH was greatest in iRBD = 47%, while abnormal spindle duration/abnormal NRH was predominant in PSP = 85% and LBD = 74%.

Conclusion

The NREM sleep biomarkers spindle duration and NRH may be useful in distinguishing patients with different neurodegenerative disorders. Larger prospective cohort studies are needed to determine whether spindle duration and NRH can be combined for prodromal assessment and/or monitoring disease progression.

Letter to the Editor on "Leveraging Biomedical Engineering Engineers to Improve Obstructive Sleep Apnea (OSA) Care for Our Stroke Patients"

Obstructive sleep apnea (OSA), a condition of recurring, episodic complete or upper airway collapse, is a common disorder, affecting an estimated 17.4% of women and 33.9% of men in the United States [1]. The first line treatment for OSA is Continuous Positive Airway Pressure (CPAP) therapy, a medical device that delivers adequate airflow and oxygenation during sleep by way of a tube that connects an air compressor to a face mask that can fit over the nose, under the nose, or over the nose and mouth.

Sleep and memory: The impact of sleep deprivation on transcription, translational control, and protein synthesis in the brain

In countries around the world, sleep deprivation represents a widespread problem affecting school-age children, teenagers, and adults. Acute sleep deprivation and more chronic sleep restriction adversely affect individual health, impairing memory and cognitive performance as well as increasing the risk and progression of numerous diseases. In mammals, the hippocampus and hippocampus-dependent memory are vulnerable to the effects of acute sleep deprivation. Sleep deprivation induces changes in molecular signaling, gene expression and may cause changes in dendritic structure in neurons. Genome wide studies have shown that acute sleep deprivation alters gene transcription, although the pool of genes affected varies between brain regions. More recently, advances in research have drawn attention to differences in gene regulation between the level of the transcriptome compared with the pool of mRNA associated with ribosomes for protein translation following sleep deprivation. Thus, in addition to transcriptional changes, sleep deprivation also affects downstream processes to alter protein translation. In this review, we focus on the multiple levels through which acute sleep deprivation impacts gene regulation, highlighting potential post-transcriptional and translational processes that may be affected by sleep deprivation. Understanding the multiple levels of gene regulation impacted by sleep deprivation is essential for future development of therapeutics that may mitigate the effects of sleep loss.

The Accuracy and Reliability of Sleep Staging and Sleep Biomarkers in Patients with Isolated Rapid Eye Movement Sleep Behavior Disorder

Purpose

This study aimed to establish the diagnostic accuracy of a previously validated sleep staging system in patients with probable isolated REM sleep behavior disorder (iRBD), and to compare physicians' diagnoses of iRBD based on REM sleep without atonia (RSWA) to non-REM hypertonia (NRH), a sleep measure independently associated with Parkinsonian spectrum disorders.

Patients and Methods

Twenty-six patients with a history of dream enactment behavior underwent a diagnostic PSG with simultaneous Sleep Profiler (SP) acquisition at two sites. PSG and SP records were sleep staged, and two sleep neurologists independently diagnosed iRBD based on the presence or absence of polysomnographic identified RSWA. Comparisons for PSG vs SP sleep staging and the qualitative presence or absence of PSG-based RSWA vs automated SP-detected NRH was performed using kappa coefficients (k), positive and negative percent agreements (PPA and NPA), and chi-square tests.

Results

The kappa scores from Sites-1 and -2 for PSG vs SP staging were different for Wake (k=0.82 vs 0.65), N2 (k=0.63 vs 0.72) and REM (k=0.83 vs.0.72). The by-site kappa values for stage N3 increased from 0.72 and 0.37 to 0.88 and 0.74 after PSG records were reedited. The kappa values for between-physician agreement in iRBD diagnoses were fair (k = 0.22). The agreement between each physician's iRBD diagnoses and NRH were also fair (k=0.29 and 0.22). Abnormal NRH agreed with at least one physician's iRBD diagnosis in 83% of the records. The PPA resulting from between-physician iRBD agreement was stronger and the NPA weaker than the values obtained from comparison of each physician's iRBD diagnosis and abnormal NRH.

Conclusion

The potential utility of RSWA and stage N3 as neurodegenerative disorder biomarkers was influenced by between-site variability in visual scoring. The degree to which NRH was associated with iRBD was similar to the between-physician agreement in their diagnosis of iRBD using RSWA.