Rapid eye movement sleep behavior disorder

RBD is a parasomnia characterized by the loss of normal skeletal muscle atonia during REM sleep, leading to enactment of dreams, often resulting in violent or injurious behaviors.

The pathophysiology of RBD is thought to involve dysfunction of the brainstem circuits responsible for maintaining normal REM sleep atonia and suppressing behaviors during REM sleep, particularly the sublaterodorsal nucleus and the magnocellular nucleus of the medulla. This dysfunction may be due to neurodegenerative processes, such as Parkinson's disease, Lewy body dementia, multiple system atrophy.

The prevalence of RBD in the general population is estimated at 0.5%, with a higher prevalence of 2-7% in the elderly, depending on the diagnostic tool used.

Risk factors for RBD include male gender, age > 50 years, and the presence of neurodegenerative diseases, particularly Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Other risk factors include antidepressant use and a history of traumatic brain injury.

Clinically, RBD typically presents with dream-enacting behaviors such as talking, shouting, punching, kicking, biting, or jumping out of bed, which can lead to injury. Non-violent behaviors may include laughing, gesturing, crying, and singing. These behaviors often gradually increase in frequency and intensity over time.

Idiopathic RBD has a high likelihood of progressing to a neurodegenerative disorder, most commonly one of the synucleinopathies, such as Parkinson's disease, dementia with Lewy bodies, or multiple system atrophy. Probable RBD carries a 2.2-fold increased risk of developing MCI or Parkinson's disease over 4 years.