The rapid eye movement (REM) stage of sleep has recently garnered attention for its potential association with neurodegenerative brain conditions such as Parkinson's disease and dementia with Lewy bodies. (Miriam Alonso/ Pexels)

The Enigmatic Connection: REM Sleep Behavior Disorder and Dementia

By Yash Manchanda

Modified May 30, 2023 20:06 GMT

Rapid eye movement (REM) stage of sleep has recently attracted interest due to its potential link to neurodegenerative brain conditions such as Parkinson's disease and dementia with Lewy bodies. This disorder, known as REM sleep behavior disorder (RBD), affects approximately 1 percent of the general population worldwide and about 2 percent of adults over 65.

Despite the fact that this condition can affect anyone at any age, people in their 40s and 50s commonly experience symptoms. Regardless of the disorder's relatively low prevalence, its potential role as a precursor or risk factor for dementia warrants further investigation.

What is REM sleep behavior disorder?

REM sleep behavior disorder manifests during the REM stage of sleep, which accounts for approximately 20 percent to 25 percent of the total sleep duration but progressively occupies a larger proportion as the night unfolds. (Andrea Piacquadio/ Pexels)

REM sleep behavior disorder occurs during the REM stage of sleep, which comprises only 20 percent to 25 percent of total sleep time but increases in proportion throughout the night. During REM sleep, the brain rhythms resemble wakefulness, muscles lose tone, and the eyes move rapidly behind closed eyelids. Usually, this stage is characterized by muscle twitches and fluctuations in respiratory rate and blood pressure.

However, individuals with REM sleep behavior disorder act out their dreams. The precise reasons for this phenomenon remain unclear, but patients often report experiencing violent dream content during REM sleep behavior disorder, including being pursued or engaging in self-defense. As they sleep, they may shout, moan, scream, kick, punch, and thrash about.

Unfortunately, these actions often result in injuries, such as falls from bed or accidental harm to a partner. During sleep, approximately 60 percent of patients with this disorder and 20 percent of their bed partners experience injuries.

Accurate testing, including a sleep study, is necessary to determine if a patient has REM sleep behavior disorder instead of another sleep disorder like obstructive sleep apnea, which is characterized by breathing interruptions during sleep. While this disorder can occur at any age, symptoms typically appear in individuals in their 40s and 50s. Antidepressants are the most common cause of REM sleep behavior disorder in individuals under 40, affecting both biological males and females equally. However, past the age of 50, it is more common in biological males.

REM sleep behavior disorder causes

The exact underlying cause of REM sleep behavior disorder still eludes our understanding. In certain instances, there is an absence of a clear identifiable cause for the disorder. (cottonbro studio/ Pexels)

The underlying cause of REM sleep behavior disorder remains poorly understood. In some cases, a clear cause cannot be identified. However, there are instances where the disorder may be attributed to specific factors, including obstructive sleep apnea, narcolepsy, psychiatric disorders, use of antidepressants, autoimmune disorders, and brain lesions, which are areas of damaged brain tissue.

Regardless of the specific cause, REM sleep behavior disorder may be associated with synucleinopathies, a group of neurodegenerative disorders characterized by the accumulation of α-synuclein protein aggregates in brain cells. Parkinson's disease is the most common neurodegenerative disorder in this group, while others include dementia with Lewy bodies, multiple system atrophy, and pure autonomic failure.

REM sleep behavior disorder has the potential to manifest before the onset of these diseases or at any stage throughout the disease progression.

Link Between REM Sleep Disorder and Dementia

A study conducted by researchers at the Mayo Clinic in the United States monitored individuals diagnosed with REM sleep behavior disorder for an average duration of 12 years. (Andrew Neel/ Pexels)

The association between REM sleep behavior disorder and neurodegenerative disorders, particularly dementia, raises important questions about the potential role of this sleep disorder as an early indicator or risk factor for these conditions. While more research is needed to fully elucidate the relationship, several studies have provided valuable insights.

One study conducted by researchers at the Mayo Clinic in the United States followed individuals with REM sleep behavior disorder for an average of 12 years. The findings revealed that approximately 81 percent of the participants eventually developed a neurodegenerative disorder, with dementia being the most common outcome.

Another study published in the journal Brain examined the long-term prognosis of patients with REM sleep behavior disorder. The researchers found that after 12 years of follow-up, around 73 percent of the patients developed a neurodegenerative disorder, such as Parkinson's disease or dementia with Lewy bodies.

These studies suggest that REM sleep behavior disorder may serve as an early indicator or prodromal stage of neurodegenerative diseases, providing an opportunity for early intervention and monitoring. Identifying individuals with REM sleep behavior disorder and closely monitoring their cognitive and motor functions could be crucial in detecting the onset of dementia and other related conditions.

While more research is needed to uncover the precise mechanisms and develop targeted treatments, recognizing the potential significance of REM sleep behavior disorder in the context of neurodegenerative diseases is a crucial step forward. Early identification and intervention could potentially delay or mitigate the progression of these debilitating conditions, ultimately improving the quality of life for individuals at risk.

REM sleep behavior disorder, a relatively unfamiliar sleep disorder, has attracted significant attention due to its connections with neurodegenerative diseases such as Parkinson's disease and dementia with Lewy bodies. (RDNE Stock project/ Pexels)

By understanding the underlying mechanisms and exploring the links between REM sleep behavior disorder and neurodegenerative disorders, researchers can contribute to the development of early detection methods and targeted interventions, ultimately aiming to improve the lives of individuals at risk of these devastating conditions.

Edited by
Babylona Bora