From the Guidelines
REM behavior disorder (RBD) is strongly associated with several neurodegenerative disorders, particularly synucleinopathies, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, as well as other conditions like narcolepsy and certain brainstem lesions. The most common neurological conditions linked to RBD are Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, with RBD often serving as an early predictor of these conditions, as noted in the 2023 American Academy of Sleep Medicine clinical practice guideline 1. In fact, studies have shown that more than 80% of patients with idiopathic RBD eventually develop one of these synucleinopathies within 10-15 years of RBD diagnosis. Other neurological disorders less commonly associated with RBD include certain brainstem lesions and rarely, Alzheimer's disease. The connection between RBD and these conditions stems from dysfunction in the brainstem structures that normally inhibit muscle activity during REM sleep, particularly the sublaterodorsal nucleus and related pathways, as discussed in the context of secondary RBD due to a medical condition 1.
Some key points to consider in the association between RBD and neurological disorders include:
- The presence of RBD in a patient should prompt consideration of underlying neurological disease, especially when accompanied by other neurological symptoms such as tremor, cognitive changes, or autonomic dysfunction.
- Secondary RBD can occur in the setting of alpha-synuclein disorders such as dementia with Lewy bodies (DLB) and Parkinson's disease (PD), as well as in the setting of type 1 narcolepsy, a disorder of orexin deficiency 1.
- The choice of treatment for RBD should consider the patient's underlying disease and attendant symptoms, as patients with neurodegenerative disorders frequently experience other symptoms affecting motor function, cognitive domains, and the autonomic system, along with sleep and daytime alertness 1.
Overall, the association between RBD and various neurological disorders highlights the importance of considering underlying neurodegenerative conditions in patients presenting with RBD, and tailoring treatment approaches to address both the RBD and the underlying condition, as informed by the latest clinical practice guidelines 1.
From the Research
Neurological Disorders Associated with REM Behavior Disorder
The following neurological disorders are associated with REM behavior disorder:
- Parkinson's disease 2, 3, 4, 5
- Dementia with Lewy bodies 2, 3, 4, 5
- Multiple system atrophy 3, 4
- Progressive supranuclear palsy 4
- Spinocerebellar ataxias 3
- Narcolepsy 6
- Paraneoplastic neurological syndromes 6
- Autoimmune disorders 6
- CNS lesions (e.g., tumors, stroke) 6
- Other neurological disorders 6
- Psychiatric disorders (PTSD, mood disorders) 6
Key Findings
- RBD can be an early sign of neurodegenerative diseases, often preceding other symptoms by several years 2, 3, 4, 5
- The risk of dementia and parkinsonism in idiopathic RBD is estimated to be 6.3% per year, with 73.5% converting after 12-year follow-up 5
- Abnormal quantitative motor testing, objective motor examination, olfactory deficit, mild cognitive impairment, and other factors are predictors of phenoconversion in iRBD 5