Understanding the Root of REM Behavior Disorder and Other Parasomnias

Alberto Ramos, MD, FAAN

Parasomnias are sleep disorders that involve abnormal behaviors, emotional experiences, perceptions, and dream activity, occurring during specific sleep stages or sleep-wake transitions. The third edition of the International Classification of Sleep Disorders categorized parasomnias into 3 categories: non-rapid eye movement (REM) related, REM related, and those not specific to sleep state. They can also be categorized based on whether they are primary disorders of the sleep state form which they arise (e.g. sleepwalking) or are secondary to other medical or psychiatric disorders (e.g., nocturnal panic attacks).

At the 2024 American Academy of Neurology (AAN) Annual Meeting, held April 13-18, in Denver, Colorado, a session led by Alberto Ramos, MD, FAAN, covered parasomnias, including REM behavior disorder. The session, comprised of other speakers including Eric Geil, MD, and Salim I. Dib, MD, FAAN, covered the normal variants of sleep, the theories of REM sleep, and the influence of the COVID-19 pandemic on sleep patterns. In addition, the session covered the diagnostic criteria, risk factors, and treatment options for patients with parasomnias.

Ramos, director of the Sleep Disorders program at the University of Miami, sat down with NeurologyLive® during the meeting to discuss the session, and the differences in treating REM and non-REM disorders. In addition, he spoke on the connection between REM sleep and later-life neurodegenerative disorders, and the theories behind this link. Furthermore, he gave perspective on why recognizing and treating these disorders early is so critical for overall long-term health.

Discuss the session you’re leading and why this was of interest to you?

The parasomnia course was a two-hour course that included several speakers, going through all the different clinical, diagnostic, and treatment components of different parasomnias. There are two types of parasomnias, those that come out of non-rapid eye movement (REM) sleep and rapid eye movement sleep. We discussed the clinically important parasomnias from both types, discussed both cases, and made it as interactive as possible. It was a basic course and was intended to be an introductory course. It was great for your the non-sub specialists, specialists rested in fellowship or other type of more general neurology. It was a great course to understand these disorders and recognize and identify them, and potentially treat them.

Despite the common crossover in sleep disorders, how does REM sleep disorder differ from others?

Rapid eye movement sleep, or REM behavior disorder, is these disorders where people act out their dreams. When you're doing normal rapid eye movement sleep you have all these images in your brain while we're dreaming but you're paralyzed, except for the respiratory muscles. In REM behavior disorder, there's a breakdown with the systems, and the person starts to act out their dreams. And there are different reasons for it.

One of them is that these that people can potentially develop this from an alpha-synucleinopathy that’s associated with Parkinson disease or Parkinson disease dementia, Lewy Body disease, among others. We went through why people develop this disease, the different causes of it, and of course, the treatment options and being safe. Making sure that the person doesn't injure himself or herself or the bed partner. Of course, there are different pharma medical treatments that will probably give.

Is there a connection between REM and later-life neurocognitive disorders?

That's a great question. Yes, there's definitely a link between having REM behavior disorder [and late-life neurocognitive disorders], but it’s the idiopathic type. We’re not sure how exactly to explain it but after 10 to 15 years, more than 50% and even up to 80% of people will develop one of these neurocognitive disorders, being Parkinson disease, dementia, Lewy Body and other types of alpha-synucleinopathies. Even though we don’t have any treatments that will change the trajectory of these people, the hopes is that is that eventually research will catch up, and we will be able to develop neuroprotective agents that can treat them and hopefully either prevent or minimize the chances of developing these diseases.

What are some of the theories behind where REM comes from and how to best treat it?

It’s unclear where REM sleep comes from. It seems to serve many important functions for the brain, one of them being to allow us to consolidate certain memories. People argue that REM sleep is extremely important for the emotional memory. If you have certain learnings from the data or emotionally charge, you’re able to process that information better during REM sleep. And to some extent also helps with minimizing against anxiety and depressive symptoms.

It's not the cure for it, or the treatment for it, but nonetheless there seems to be a very strong correlation. And to some extent, it seems that you can argue associations during REM sleep. If you're learning one new thing, these cortical to cortical associations that have happened during rapid eye movements, REM sleep allows you to put these new learnings into the hard drive of your brain and you associate different things, put them together.

There's also a question that maybe REM sleep allows for things such as being able to regulate temperature and the brainstem, among other important things. These are some of the different hypotheses that are out there. There's also this question that maybe the REM sleep at some point must be some sort of proto consciousness, meaning that, we're having this conscious experience right now and we're alert and aware of our what's going on, it has been proposed that REM sleep precedes these conscious experience.

In terms of REM behavior disorder, what are some of the major research areas we should be focusing on going forward?

I'm probably biased towards it, but nonetheless, looking at the connection of how sleep could potentially either improve, mitigate, or even prevent neurocognitive disorders such as Alzheimer disease, or maybe others? That's going to be one of the things that I'm looking forward to. There's a lot of research right now in Alzheimer disease and neurological disorders, and they're having great advances. Sleep itself not only blends very nicely into our discipline in terms of neurology, but I think it will be essential to keep bringing it up.

Transcript was edited for clarity. Click here for more coverage of AAN 2024.