Diseases and Disorders

REM Sleep Behavior Disorder: An Overview

Priya Vijayakumar


Introduction

Rapid eye movement (REM) sleep behavior disorder (RBD) was first acknowledged by the scientific community in 1985; doctors Mark Mahowald and Carlos Schenck of the University of Wisconsin published four cases of men over the age of 50 with RBD. These case studies detailed RBD’s hallmark symptom of violent dream enactment during REM stages of sleep (“History of REM Sleep Behavior Disorder,” n.d.).  REM is a stage of sleep that alternates with slow wave sleep. Characterized by rapid eye movement, active dreaming, and wakeful-like brain activity, REM increases in frequency and duration until wakefulness. A landmark characteristic of REM sleep is atonia or full-body paralysis, except for the muscles used in respiration and eye movement. Patients with RBD fail to lapse into atonia during REM sleep and thus, experience abnormal and often dangerous mobility during dreaming states while sleeping (“Chapter 6: Sleep,” n.d.).

 

Physiology

    During normal REM sleep, atonia is achieved by inhibition of locomotor activity in the pons and neurons in the nucleus reticularis magnocellularis, a region of the medulla in the brain. In the case of RBD, these inhibitors of motor function during REM sleep are impaired, thus giving patients the ability to act out their dreams during this stage of sleep (“REM Behavior Disorder (RBD) as an Early Marker for Development of Neurodegenerative Diseases,” n.d.).

 

Notable Features

    There are two forms of RBD: idiopathic and symptomatic. Emerging with no apparent triggers, Idiopathic RBD is linked to a 12-year risk of 52.4% for developing a neurodegenerative disorder (Iranzo, Santamaria, & Tolosa, 2009). Idiopathic RBD is strongly linked to the onset of Parkinson’s disease (PD) although not all PD patients experience RBD (Coeytaux, Wong, Grunstein, & Lewis, 2013). Symptomatic RBD, on the other hand, occurs alongside other neurological disorders, such as narcolepsy. Disorders that may occur prior to, during, or after the development of RBD include multiple system atrophy, prior encephalitis, progressive supranuclear palsy, Lewy body dementia, and brainstem infarction (Olson, Boeve, & Silber, 2000).

    RBD is characterized by persistent movements and vocalizations during REM sleep. Dream-enacted behavior can injure both patients suffering from RBD, as well as bed partners. While reports show that it is rare for patients with RBD to leave their beds, as noted in sleepwalking, 20% of patients are likely to face unconsciousness and head injuries as a result of RBD (Iranzo, Santamaria, & Tolosa, 2009).

 

Trends and Risk Factors

    Affecting nearly 0.5% of the general population, RBD is nine times more likely to occur in men than in women (“REM Behavior Disorder (RBD) as an Early Marker for Development of Neurodegenerative Diseases,” n.d.). The predominance of RBD in men has been inconclusively theorized to involve a correlation between sex hormones and aggressive behavior. RBD may also occur in women;, however, it is less likely to be diagnosed due to less violent dream enactment (Coeytaux, Wong, Grunstein, & Lewis, 2013; Irfan & Howell, 2016). RBD is predominant in men over the age of 50, most likely due to the predated onset of neurological disorders in such an age range (Coeytaux, Wong, Grunstein, & Lewis, 2013). Two proven risk factors of RBD include exposure to pesticides and smoking cigarettes (“Risk Factors Identified for REM Sleep Behavior Disorder,” n.d.).

 

Diagnosis

    The first diagnostic tool for RBD is polysomnography, also known as a sleep study. Polysomnography monitors brain activity, blood oxygen levels, heart rate, respiration and muscle tone in a laboratory setting. Electromyography during sleep is also effective in RBD diagnosis; it is used during sleep studies as well (Mayo Clinic Staff, n.d.; Coeytaux, Wong, Grunstein, & Lewis, 2013). Reports of abnormal mobility during sleep also serve to indicate the presence of RBD when paired with clinical forms of diagnosis (“REM Behavior Disorder (RBD) as an Early Marker for Development of Neurodegenerative Diseases,” n.d.).

 

Treatment and Preventative Measures

    Treatment of RBD reduces the likelihood of injuries due to dream enactment to the patient and his or her bed partner. One drug, Clonazepam, reduces RBD symptoms in 90% of patients (“History of REM Sleep Behavior Disorder,” n.d.; Iranzo, Santamaria, & Tolosa, 2009). Clonazepam acts on GABA receptors to suppress abnormal mobility during REM sleep. Melatonin is another potent drug used to treat RBD. The use of antidepressant medications are heavily discouraged to those with RBD. Other preventative measures include removing obstructive furniture or placing mattresses at lower elevations to reduce the risk of injury itself (Iranzo, Santamaria, & Tolosa, 2009).


References


  1. Risk Factors Identified for REM Sleep Behavior Disorder | Lewy Body Dementia Association. (n.d.). Retrieved July 29, 2016, from https://www.lbda.org/content/risk-factors-identified-rem-sleep-behavior-disorder

  2. REM Behavior Disorder (RBD) as an Early Marker for Development of Neurodegenerative Diseases. (n.d.). Retrieved July 29, 2016, from http://www.bjmp.org/content/rem-behavior-disorder-rbd-early-marker-development-neuro degenerative-diseases

  3. Irfan, M., & Howell, M. J. (2016). Rapid Eye Movement Sleep Behavior Disorder: Overview and Current Perspective. Curr Sleep Medicine Rep Current Sleep Medicine Reports, 2(2), 64-73. doi:10.1007/s40675-016-0038-z

  4. Iranzo, A., Santamaria, J., & Tolosa, E. (2009). The clinical and pathophysiological relevance of REM sleep behavior disorder in neurodegenerative diseases. Sleep Medicine Reviews, 13(6), 385-401. doi:10.1016/j.smrv.2008.11.003

  5. History of REM Sleep Behavior Disorder. (n.d.). Retrieved July 29, 2016, from https://sleepfoundation.org/sleep-disorders-problems/rem-behavior-disorder/history

  6. Olson, E. J., Boeve, B. F., & Silber, M. H. (2000). Rapid eye movement sleep behaviour disorder: Demographic, clinical and laboratory findings in 93 cases. Brain, 123(2), 331-339. doi:10.1093/brain/123.2.331

  7. Mayo Clinic Staff. (n.d.). Polysomnography (sleep study). Retrieved July 29, 2016, from http://www.mayoclinic.org/tests-procedures/polysomnography/basics/definition/prc-2001 3229

  8. Coeytaux, A., Wong, K., Grunstein, R., & Lewis, S. J. (2013, November). REM sleep behaviour disorder. Australian Family Physician, 42(11), 785-788.

  9. Chapter 6: Sleep. (n.d.). In Brain Facts (pp. 32-35). Society for Neuroscience

Priya Vijayakumar

Priya Vijayakumar


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