Normally, when we go into REM sleep, we become paralyzed. The only muscles that continue to work at routine levels are the diaphragm and the eye muscles. However, there are individuals who lack this inhibition and can move while dreaming. In these folks, the dreams are frequently violent and result in harm to themselves or a bed partner.
We know that this disorder seems to be more common in middle-aged men, although by no means exclusively so. We also know that up to 40% of these people, when followed over a period of time, go on to develop Parkinson’s or Parkinson-like disorders such as dementia with Lewy bodies or multiple system atrophy.
What we did not know is why. In fact, I devote a chapter of my new book Sleep Soundly Every Day, Feel Fantastic Every Night to the topic of REM Behavior Disorder (RBD). It is a very real problem for numerous Americans, and unfortunately a source of embarrassment to many. In fact, I make it a point to ask all of my new patients “Have you ever been known to act out your dreams?” It never ceases to amaze me as to how many answer affirmatively.
We may now have the answer as to why this sleep disorder is so commonly followed by Parkinson’s disease. In a paper presented at the 2014 annual meeting of the Society of Nuclear Medicine and Molecular Imaging, scientists presented the results of an eight-year study. Twenty-one patients with REM Behavior Disorder but no evidence of Parkinson’s were followed using specialized brain scans, called single photon emission computed tomography (SPECT). These scans allow clinicians to view bodily functions as opposed to only structure. Ten of these individuals showed dopamine abnormalities at baseline and eight years later, seven of them went on to develop Parkinson’s disease or similar neurodegenerative disorders.
What does this mean? I believe it signals a very important breakthrough for those with RBD. Up until now, all I could tell my patients with this common sleep-related disorder was that they had a 30 to 40% chance of developing Parkinson’s. However, now using techniques such as SPECT, we may be able to accurately predict who is most at risk for developing Parkinson’s. Just as important is that there is research being done on medications that may halt the progression of Parkinson’s when it is discovered in the early stages. Ultimately, early recognition of RBD might go a long way to decreasing this disabling and deadly disease. Consequently, if you or a loved one acts out dreams, it is imperative to bring it to the attention of your health care provider.