REM behavior disorder and Parkinson's: A reason to cover their relationship in Intro Psych

[sue_frantz]

With the Intro Psych course, we have the ability to save lives. For example, our discussion of attention may help students stay off their phones while driving or help students refuse to ride with someone who talks on their phone while driving. Our discussion of stress and evidence-based coping strategies may help students find ways to reduce stress or cope better with their stress, leading to healthier outcomes in both the short- and long-term. I had another example just this week. After covering sleep, one of my students is encouraging his father to get screened for sleep apnea.

Here's another way that Intro Psych can save lives that I just learned about from the February 2023 issue of Scientific American (Kwon, 2023). Of those diagnosed with REM behavior disorder, up to 80% will be diagnosed in 10 to 12 years with a neurodegenerative disease, most commonly Parkinson’s disease.

When the common symptoms of Parkinson’s appear—such as hand tremors (although hand tremors do not appear in everyone with Parkinson’s)—over 40% of the dopamine-producing neurons in the substantia nigra of the basal ganglia are gone (Ohtsuka et al., 2013). (I’ve also seen medical websites say 50% and 80%, but they don’t site a source.) Let’s just say that bunches of neurons have been lost before the traditional symptoms appear.

MRI can be used to detect the loss of neurons in the basal ganglia (Bae et al., 2021), but, of course, most people don’t get an MRI until they show symptoms. Earlier detection means being able to start interventions earlier which may slow the progression of the disease (Prashanth & Dutta Roy, 2018).

During REM sleep (and for most of us), our major muscle groups are turned off. In REM behavior disorder, the major muscle groups remain online resulting in an acting out of the dreams. Alan Alda was being chased, so he picked up a sack of potatoes and threw them at his attacker. When Alda awoke, he saw that he had thrown a pillow at his wife. Alda had seen a 2015 news story about the emerging evidence of REM behavior disorder being a marker for the potential development of Parkinson’s. A brain scan confirmed it; Alda had Parkinson’s (Kwon, 2023).

There is evidence that neurodegeneration and a buildup of a protein called synuclein (click for pronunciation) within the pons and medulla (both within the brainstem) play a role in REM behavior disorder (Chiaro et al., 2018). One possibility is that, over time—say, 10 to 12 years—the synuclein protein clusters spread up into the basal ganglia, damaging those neurons. When enough of those neurons are damaged, we may begin to see Parkinson’s symptoms, such as hand tremors.

But here’s the fascinating part. A person with Parkinson’s who experiences slowed muscle movement, rigid muscles, and tremors while awake, has these symptoms seemingly vanish when showing symptoms of REM behavior disorder. While the symptoms of Parkinson’s are due in large part to damage within the basal ganglia, REM sleep bypasses the basal ganglia. While acting out a dream, full movement returns. This raises an interesting possibility. Could treatments bypass the basal ganglia when the person is awake? In the meantime, researchers are looking for ways to reduce synuclein before it does so much damage, and a diagnosis of REM behavior disorder may be one way to identify people at risk but before significant neuron loss occurs (Kwon, 2023).

REM behavior disorder has an estimated prevalence of 1% (Haba-Rubio et al., 2018) in the general population. If you teach 200 Intro Psych students annually, and each student has, on average, 10 relatives (totally made up number; I have over 60 relatives, including siblings, aunts, uncles, cousins, nieces, and nephews), sharing this information on the relationship between REM behavior disorder and Parkinson’s with your students could reach 2,000 people.  At 1% prevalence, we would expect 20 of them to have REM sleep disorder. If 80% are expected to develop Parkinson’s (or similar disease) in 10 to 12 years, that would be 16 of them. If those 16 were diagnosed early, the progression of Parkinson’s could be slowed. Your math may vary, but the result is the same. What you cover in Intro Psych could save lives.

References

Bae, Y. J., Kim, J.-M., Sohn, C.-H., Choi, J.-H., Choi, B. S., Song, Y. S., Nam, Y., Cho, S. J., Jeon, B., & Kim, J. H. (2021). Imaging the substantia nigra in Parkinson disease and other Parkinsonian syndromes. Radiology, 300(2), 260–278. https://doi.org/10.1148/radiol.2021203341

Chiaro, G., Calandra-Buonaura, G., Cecere, A., Mignani, F., Sambati, L., Loddo, G., Cortelli, P., & Provini, F. (2018). REM sleep behavior disorder, autonomic dysfunction and synuclein-related neurodegeneration: Where do we stand? Clinical Autonomic Research, 28(6), 519–533. https://doi.org/10.1007/s10286-017-0460-4

Haba-Rubio, J., Frauscher, B., Marques-Vidal, P., Toriel, J., Tobback, N., Andries, D., Preisig, M., Vollenweider, P., Postuma, R., & Heinzer, R. (2018). Prevalence and determinants of rapid eye movement sleep behavior disorder in the general population. Sleep, 41(2). https://doi.org/10.1093/sleep/zsx197

Kwon, D. (2023, February). When dreams foreshadow brain disease. Scientific American, 328(2), 58–63. https://doi.org/10.1038/scientificamerican0223-56

Ohtsuka, C., Sasaki, M., Konno, K., Koide, M., Kato, K., Takahashi, J., Takahashi, S., Kudo, K., Yama**bleep**a, F., & Terayama, Y. (2013). Changes in substantia nigra and locus coeruleus in patients with early-stage Parkinson’s disease using neuromelanin-sensitive MR imaging. Neuroscience Letters, 541, 93–98. https://doi.org/10.1016/j.neulet.2013.02.012

Prashanth, R., & Dutta Roy, S. (2018). Early detection of Parkinson’s disease through patient questionnaire and predictive modelling. International Journal of Medical Informatics, 119, 75–87. https://doi.org/10.1016/j.ijmedinf.2018.09.008